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Acute Renal Failure (ARF) / Acute Kidney Injury (AKI)

Note on terminology: The term "Acute Renal Failure" (ARF) has largely been replaced by Acute Kidney Injury (AKI) in current literature, as it better reflects the spectrum from mild to severe dysfunction. Both terms refer to the same clinical entity.

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1. Definition

KDIGO Staging Criteria

• Goldman-Cecil Medicine, International Edition, pp. 1241-1248
• Brenner and Rector's The Kidney, 2-Volume Set

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2. Classification / Types

A. Prerenal AKI (60-70% of cases)

B. Intrinsic (Renal/Intrarenal) AKI (25-40% of cases)

• Tubular cell injury (80-90% of intrinsic): ATN from ischemia/toxins
• Acute Interstitial Nephritis (5-10%)
• Acute Glomerulonephritis (<5%)

C. Postrenal AKI (5-10% of cases)

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3. Causes

Prerenal Causes

• Hemorrhage (traumatic, GI, surgical)
• GI losses (vomiting, diarrhea, NG suction)
• Renal losses (overdiuresis, diabetes insipidus)
• Third-spacing (pancreatitis, hypoalbuminemia, burns, fever/sweating)

• Cardiogenic shock / acute cardiac failure
• Septic shock
• Cirrhosis/liver failure
• Anaphylaxis

• NSAIDs (reduce prostaglandin-mediated afferent dilation)
• ACE inhibitors and ARBs (reduce efferent vasoconstriction)
• Cyclosporine, radiocontrast agents

Intrinsic Renal Causes

• Any prolonged prerenal cause that is not corrected promptly
• Drug nephrotoxicity: aminoglycosides, amphotericin B, cisplatin, radiocontrast agents, vancomycin, tenofovir, acyclovir, foscarnet, NSAIDs
• Endogenous toxins: myoglobin (rhabdomyolysis), hemoglobin (hemolysis), uric acid, calcium oxalate, pancreatic enzymes
• Exogenous toxins: metals (iron, cadmium), toluene, ethylene glycol, cocaine, methotrexate, tacrolimus

• Drugs: sulfonamides, penicillins, cephalosporins, ciprofloxacin, rifampin, NSAIDs, proton pump inhibitors, furosemide, thiazides, allopurinol, checkpoint inhibitors
• Infections: Legionella, leptospirosis, streptococcus, EBV, CMV, SARS-CoV-2, TB
• Systemic disease: SLE, Sjögren syndrome, sarcoidosis, cryoglobulinemia

• Rapidly progressive glomerulonephritis (RPGN): ANCA-associated vasculitides, Goodpasture disease, crescentic GN
• Thrombotic microangiopathies (TTP, HUS)
• Cryoglobulinemia

• Aortic dissection
• Renal artery/vein thrombosis
• Atheroembolism

• Rhabdomyolysis
• Hepatorenal syndrome
• Urate nephropathy

Postrenal Causes

• Lower tract: Prostatic hypertrophy (most common in older men), prostate/bladder/cervical cancer, neurogenic bladder (diabetes, spinal cord disease)
• Ureteral: Bilateral renal calculi, retroperitoneal fibrosis, endometriosis, metastatic colon cancer, lymphoma, papillary necrosis, blood clots
• Tietz Textbook of Laboratory Medicine, 7th Edition; Goldman-Cecil Medicine; Brenner & Rector's The Kidney

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4. Pathophysiology

Prerenal Pathophysiology

1. Sympathetic activation and catecholamine release (norepinephrine) → afferent arteriolar constriction
2. RAAS activation → Angiotensin II production → preferential efferent arteriolar constriction → initially preserves GFR via maintained glomerular hydrostatic pressure → also stimulates proximal tubular Na+/H+ exchangers to augment Na reabsorption
3. ADH release → vasoconstriction, water retention, urea back-diffusion into the papillary interstitium
4. Prostaglandins (PGE₂, PGI₂) counteract vasoconstriction - hence NSAIDs that block these worsen prerenal AKI

Intrinsic Renal Pathophysiology (ATN - Ischemic)

1. Initiation/Inflation phase (hours): Ischemia causes tubular epithelial injury, loss of brush border, cellular swelling, and loss of polarity. Sublytic injury disrupts cytoskeletal architecture - Na/K-ATPase loses its basolateral orientation, allowing back-leak of filtrate. ROS generation begins.
2. Extension phase: Continued microvascular ischemia especially in the outer medulla (S3 segment of proximal tubule is particularly vulnerable due to its high metabolic demand but low oxygen supply). Inflammatory mediators are activated - TNF-α, IL-10, CXCL1, neutrophil elastase. Endothelial dysfunction leads to coagulation and continued vasoconstriction. Cell death occurs via necrosis and apoptosis.
3. Maintenance phase (days to weeks): GFR stabilizes at a low level. Tubular obstruction by cellular debris (casts), back-leak of filtrate across denuded tubular epithelium, and intense vasoconstriction maintain reduced GFR.
4. Recovery phase: Tubular epithelial cell regeneration and redifferentiation. GFR gradually recovers over days to weeks.

Postrenal Pathophysiology

• Brenner and Rector's The Kidney, 2-Volume Set, pp. 906, 912

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5. Diagnostic Approach

Clinical Presentation

• Often clinically silent in early stages
• Some patients note change in urine volume/color
• Obstructive AKI may cause hematuria and flank pain
• Advanced AKI: uremic symptoms (anorexia, fatigue, nausea/vomiting, pruritus, reversal of sleep-wake cycle)
• Examination: pulmonary/peripheral edema, pericardial/pleural friction rub, myoclonus, asterixis

Serum Labs

• Serum creatinine (serial measurements - single values are insufficient; influenced by muscle mass, medications)
• BUN/creatinine ratio: >20:1 suggests prerenal; <10-15:1 suggests intrinsic
• Electrolytes: Na+, K+, Cl-, HCO3-
• Calcium, phosphorus
• CBC with differential
• Serum uric acid (in tumor lysis syndrome context)

Urine Studies

Urinalysis and Microscopy

Fractional Excretion of Sodium (FENa)

Renal Failure Index (RFI)

• RFI <1: Prerenal
• RFI >2: ATN

Novel Biomarkers

• NGAL (Neutrophil gelatinase-associated lipocalin): Elevated within 2 hours of tubular injury
• KIM-1 (Kidney Injury Molecule-1): Proximal tubule injury marker
• Cystatin C: Earlier indicator of GFR decline than creatinine
• IL-18: Marker of ischemic ATN
• TIMP-2 and IGFBP7 (urinary): Combined test (NephroCheck) for cell cycle arrest in tubular injury
• α1-microglobulin and urinary cystatin C: Predict need for RRT (AUC ~0.86)

Imaging

• Renal ultrasound (first-line): Assess kidney size, echogenicity, hydronephrosis (postrenal), blood flow (Doppler)
• Bladder catheterization: Simultaneous diagnostic and therapeutic for lower tract obstruction
• CT scan/MRI: Retroperitoneal causes, renal vasculature
• Renal biopsy: When cause of intrinsic AKI is unclear after non-invasive workup

Fluid Challenge

• Goldman-Cecil Medicine, pp. 1246-1247; Henry's Clinical Diagnosis and Management by Laboratory Methods; Roberts and Hedges' Clinical Procedures in Emergency Medicine

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6. Management

General Principles

1. Remove or treat the offending cause
2. Optimize intravascular volume
3. Avoid nephrotoxins
4. Manage electrolyte and metabolic complications
5. Initiate RRT when indicated

Prerenal AKI

• Prompt volume resuscitation: IV crystalloids (balanced crystalloids preferred over normal saline in critically ill patients - SMART trial evidence)
• Treat underlying cause (heart failure, cirrhosis, sepsis - these may not respond to fluids alone)
• Discontinue NSAIDs, ACE inhibitors, ARBs where possible
• For acute hypertension-related ARF: fenoldopam, nicardipine, or clevidipine (preserve renal blood flow while reducing SVR)

Intrinsic AKI (ATN)

• No specific therapy reverses established ATN
• Supportive care is the cornerstone

• Daily loop diuretics (furosemide 40-80 mg IV) for volume overload; note diuretics do not shorten ATN duration or prevent it
• Restrict sodium, potassium, and protein intake

• Hyperkalemia: Sodium zirconium cyclosilicate (Lokelma) or patiromer, low-K+ diet; in emergency - calcium gluconate, insulin/dextrose, sodium bicarbonate, kayexalate, dialysis
• Hyperphosphatemia: Oral phosphate binders
• Hypocalcemia: Calcium tablets
• Metabolic acidosis: Sodium bicarbonate tablets/infusion

Intrinsic AKI (Glomerulonephritis/Vasculitis)

• Immunosuppressive therapy: Prednisone (often 1 mg/kg/day with gradual taper over 1 month) for AIN and immune-mediated GN
• Cyclophosphamide + corticosteroids for ANCA vasculitis
• Plasmapheresis for Goodpasture disease

Postrenal AKI

• Urethral/bladder catheter for lower tract obstruction (both diagnostic and therapeutic)
• Ureteral stent or percutaneous nephrostomy for ureteral obstruction from tumor/stone
• Post-obstructive diuresis should be anticipated and managed with fluid replacement

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7. Pharmacology in ARF Management

Diuretics

Loop Diuretics (Furosemide, Bumetanide, Torsemide, Ethacrynic acid)

• Mechanism: Block Na+/K+/2Cl- cotransporter (NKCC2) in the thick ascending limb of Henle (TAL) → increase urine flow and K+ excretion
• Use in ARF: Convert oliguric to non-oliguric ARF (facilitates fluid management); do NOT prevent or shorten duration of ARF; may worsen cast formation in myeloma/light-chain nephropathy
• Adverse effects: Hypokalemic metabolic alkalosis, ototoxicity (especially with aminoglycosides), hyperuricemia, hypomagnesemia, dehydration, allergic reactions (sulfonamide class - except ethacrynic acid)

Osmotic Diuretics (Mannitol)

• Mechanism: Freely filtered but not reabsorbed → osmotic water retention in proximal tubule and descending limb → water diuresis; also opposes ADH in collecting tubule
• Use: Flush nephrotoxins from tubules, reduce intracranial/intraocular pressure in concurrent injury
• Caution: Must be used carefully in renal insufficiency (can worsen fluid overload if not excreted)

K+-Sparing Diuretics (Spironolactone, Eplerenone, Triamterene, Amiloride)

• Generally avoided in ARF due to risk of severe, fatal hyperkalemia
• Triamterene + indomethacin specifically reported to cause ARF
• Triamterene may precipitate kidney stones

Vasopressors/Vasodilators

Electrolyte-Stabilizing Agents

Nephroprotective Agents

Renal Replacement Therapy (RRT)

• Acidosis: Refractory metabolic acidosis
• Electrolytes: Refractory hyperkalemia
• Intoxication: Drug/toxin removal
• Overload: Refractory volume overload/pulmonary edema
• Uremia: Uremic symptoms (encephalopathy, pericarditis, myoclonus, asterixis, seizures, pleuritis)

• Intermittent hemodialysis (IHD): Standard for hemodynamically stable patients
• Continuous RRT (CRRT - CVVH, CVVHD, CVVHDF): Preferred for hemodynamically unstable ICU patients
• Peritoneal dialysis: Alternative where vascular access is unavailable
• Goldman-Cecil Medicine, p. 1247; Katzung's Basic and Clinical Pharmacology, 16th Edition, pp. 409-417

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8. Prognosis

• About one-third of hospitalized patients with AKI have resolution within 24 hours, ~60% by 48 hours, ~70% by 72 hours
• Intrinsic AKI requiring dialysis carries high mortality (40-80% in ICU)
• Survivors of AKI have increased long-term risk of progressing to chronic kidney disease (CKD)
• Risk factors for non-recovery: pre-existing CKD, elderly age, sepsis, multiorgan failure, oliguria lasting >3 days

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9. Prevention

• Identify high-risk patients (elderly, CKD, diabetics, heart failure, volume depletion)
• Limit nephrotoxin exposure (contrast, aminoglycosides, NSAIDs)
• Adequate IV hydration before contrast procedures
• Dose-adjust renally-cleared medications
• Avoid RAAS blockers + NSAIDs combination in volume-depleted patients
• Close monitoring of serum creatinine in patients receiving nephrotoxic drugs

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• Goldman-Cecil Medicine, International Edition (pp. 1241-1248)
• Brenner and Rector's The Kidney, 2-Volume Set (pp. 906-912)
• Katzung's Basic and Clinical Pharmacology, 16th Edition (pp. 409-417)
• Tietz Textbook of Laboratory Medicine, 7th Edition (p. 1915)
• Henry's Clinical Diagnosis and Management by Laboratory Methods
• Tintinalli's Emergency Medicine: A Comprehensive Study

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Chronic Renal Failure (CRF) / Chronic Kidney Disease (CKD)

Terminology note: "Chronic Renal Failure" (CRF) is now standardized as Chronic Kidney Disease (CKD) per KDIGO guidelines, reflecting the spectrum from mild kidney damage through complete kidney failure. CRF typically refers to advanced CKD (stages 4-5).

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1. Definition

• A marker of kidney damage (e.g., albumin excretion ≥30 mg/day, urine sediment abnormalities, imaging abnormalities, pathologic abnormalities)
• OR a GFR <60 mL/min/1.73 m²

• Goldman-Cecil Medicine, International Edition, p. 1333
• Textbook of Family Medicine, 9th Edition

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2. Classification / Staging (KDIGO)

GFR Stages

Albuminuria Stages

• Goldman-Cecil Medicine, p. 1337

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3. Causes

Glomerular Diseases

• Type 1 and Type 2 diabetes - progressive albuminuria → nephrosclerosis → GFR decline

• IgA nephropathy (most common glomerulonephritis worldwide)
• Focal segmental glomerulosclerosis (FSGS)
• Membranous nephropathy
• Lupus nephritis (SLE)
• ANCA-associated vasculitis
• Goodpasture disease
• Membranoproliferative GN

Vascular Diseases

• Hypertensive nephrosclerosis (second most common cause; most common nondiabetic cause)
• Renovascular disease / renal artery stenosis
• Thrombotic microangiopathies
• Cholesterol emboli / atheroembolism
• Sickle cell nephropathy

Tubulointerstitial Diseases

• Chronic pyelonephritis / reflux nephropathy
• Analgesic nephropathy (NSAIDs, phenacetin)
• Drug nephrotoxicity (long-term: cyclosporine, tacrolimus, lithium, aristolochic acid)
• Heavy metal toxicity (lead, cadmium)
• Sarcoidosis
• Chronic interstitial nephritis

Cystic and Congenital Diseases

• Autosomal dominant polycystic kidney disease (ADPKD) - GFR declines ~4.4-5.9 mL/min/year once renal function begins to fall
• Medullary cystic kidney disease
• Alport syndrome
• Congenital anomalies (hypoplasia, dysplasia)

Obstructive Uropathy (Postrenal)

• Benign prostatic hypertrophy
• Nephrolithiasis
• Retroperitoneal fibrosis
• Neurogenic bladder
• Posterior urethral valves (pediatric)

Other / Systemic

• Amyloidosis (AL, AA)
• Multiple myeloma / light-chain nephropathy
• Systemic infections (TB, hepatitis B/C, HIV - in developing countries)
• Environmental exposures (aristolochic acid in Balkans and Asia)
• Obesity-related CKD

• Goldman-Cecil Medicine, pp. 1335-1336; Tietz Textbook of Laboratory Medicine

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4. Pathophysiology

The Intact Nephron Hypothesis / Hyperfiltration

Mechanisms of Progression

1. Proteinuria as a mediator of injury: Filtered proteins (especially albumin) are taken up by proximal tubular cells, causing tubular toxicity, interstitial inflammation, and fibrosis. This is the mechanism by which reducing proteinuria slows CKD progression.
2. RAAS over-activation: Angiotensin II drives efferent arteriolar vasoconstriction → elevated intraglomerular pressure → mechanical stress on glomerular basement membrane → podocyte injury and detachment.
3. Tubulo-interstitial fibrosis: TGF-β mediates epithelial-to-mesenchymal transition, myofibroblast activation, and excess extracellular matrix deposition → irreversible fibrosis.
4. Chronic hypoxia: Reduced peritubular capillary density and microvascular rarefaction → tubular ischemia → further injury.
5. Metabolic disturbances: Metabolic acidosis activates complement and promotes tubular injury; uremic toxins accumulate and drive inflammation.

Metabolic and Endocrine Consequences of Reduced GFR

• Erythropoietin deficiency (main mechanism)
• Hepcidin accumulation → functional iron deficiency (impaired iron mobilization)
• Shortened RBC survival in uremic milieu
• Bone marrow suppression by uremic toxins

Uremic Syndrome

• Indoxyl sulfate: cardiovascular and tubular toxin
• p-Cresyl sulfate: vascular injury
• TMAO, guanidines: neurologic toxicity
• Parathyroid hormone: pruritis, osteitis fibrosa, encephalopathy

• Brenner and Rector's The Kidney, pp. 2378
• Goldman-Cecil Medicine, pp. 1337-1340

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5. Clinical Manifestations

By System

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6. Diagnostic Approach

Criteria for CKD Diagnosis

• Albuminuria (ACR ≥30 mg/g)
• Urine sediment abnormalities
• Electrolyte abnormalities from tubular disorders
• Imaging abnormalities
• Pathologic abnormalities on biopsy
• History of kidney transplantation
• GFR <60 mL/min/1.73 m²

Step 1 - Establish Diagnosis and Stage

• CKD-EPI creatinine equation (2021, race-free): preferred initial test
• CKD-EPI cystatin C or combined creatinine + cystatin C: used as confirmatory tests; together more accurate than either alone
• Cockcroft-Gault: used for drug dosing
• Cystatin C is not affected by muscle mass or diet (but is affected by smoking, obesity, inflammation, thyroid disease, glucocorticoids)

• Spot urine albumin-to-creatinine ratio (UACR): recommended initial test (convenience, specificity)
• 24-hour urine albumin excretion rate: gold standard
• A1 (<30 mg/g), A2 (30-300 mg/g), A3 (>300 mg/g)

Step 2 - Evaluate Duration

• Review past records: prior creatinine values
• Indicators of chronicity: small echogenic kidneys on imaging, bilateral cortical thinning, chronic illness, polyuria/nocturia (loss of concentrating ability)
• Small kidneys (<9 cm) = chronic; normal or large kidneys may suggest infiltrative disease (amyloid, myeloma, polycystic kidneys, diabetic nephropathy)

Step 3 - Evaluate Markers of Kidney Damage

• Renal ultrasound (first line): kidney size, echogenicity, cortical thickness, hydronephrosis, cysts, masses
  • Small (<9 cm), echogenic kidneys = advanced CKD
  • Enlarged kidneys: ADPKD, amyloid, myeloma, diabetic nephropathy
• Doppler ultrasound: renal artery stenosis
• CT/MRI: detailed anatomy, vascular, obstruction
• Nuclear scans (DMSA/MAG3): split renal function, scarring

Step 4 - Evaluate Cause

• Serum electrolytes, BUN, creatinine
• eGFR
• CBC (normochromic, normocytic anemia)
• Glucose, HbA1c (diabetic CKD)
• Lipid panel
• Serum calcium, phosphorus, PTH, alkaline phosphatase (CKD-MBD)
• 25-OH vitamin D
• Serum protein electrophoresis (SPEP), free light chains (myeloma)
• ANA, anti-dsDNA, ANCA, anti-GBM antibodies (autoimmune/vasculitis)
• Complement C3/C4
• Hepatitis B, C, HIV serology

• Protein excretion
• Creatinine clearance (if GFR estimation is uncertain)

• Cause is unclear after non-invasive workup
• Suspected treatable glomerulonephritis or vasculitis
• Unexpectedly rapid decline in GFR
• Disproportionate proteinuria

Monitoring

• Serum creatinine/eGFR: every 3-12 months depending on stage
• UACR: every 3-12 months
• Electrolytes, bicarbonate, calcium, phosphorus, PTH: every 3-6 months at G4-G5
• CBC: every 6-12 months (earlier if anemic)
• Refer to nephrology at GFR <30 (stage G4) or earlier if rapid decline, unexplained cause, or complex management

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7. Management

1. Treatment of the underlying cause
2. Slowing disease progression
3. Managing complications
4. Preparing for renal replacement therapy

A. Treating Underlying Cause (Cause-Specific)

• Diabetic CKD: intensive glycemic control (HbA1c ~7%), BP control, RAAS blockade
• Hypertensive nephrosclerosis: BP target <130/80 mmHg
• Glomerulonephritis: immunosuppression (corticosteroids, cyclophosphamide, rituximab based on specific type)
• Obstruction: relieve surgically/endoscopically
• Drugs/toxins: stop offending agent

B. Slowing Progression (CGA Stage-Independent)

Blood Pressure Control

• Target: <130 mmHg systolic (regardless of CKD stage)
• First-line: ACE inhibitors or ARBs if proteinuria is present (reduce intraglomerular pressure and proteinuria independently of BP)
  • Monitor serum K+ and creatinine after initiation
  • A 10-30% rise in creatinine after starting RAAS blockade is acceptable and expected (efferent dilation reduces filtration pressure)
  • Avoid combination ACE inhibitor + ARB (increased adverse effects without added benefit)
• Additional agents: calcium channel blockers, diuretics, beta-blockers as needed

SGLT2 Inhibitors - New Cornerstone of Therapy

• Empagliflozin, dapagliflozin, canagliflozin: Now recommended for CKD with or without Type 2 diabetes (at appropriate eGFR thresholds)
• Mechanism: Reduce intraglomerular pressure via tubuloglomerular feedback; reduce albuminuria; cardioprotective
• Evidence: DAPA-CKD trial - dapagliflozin reduced risk of ESKD, AKI, and death in CKD patients regardless of diabetes status
• "Cornerstone of therapy except in patients who have type 1 diabetes"

Reducing Proteinuria

• ACE inhibitors / ARBs: first-line
• SGLT2 inhibitors: additional antiproteinuric effect
• Finerenone (novel non-steroidal mineralocorticoid receptor antagonist): approved for diabetic CKD with albuminuria - reduces CKD progression and cardiovascular events
• GLP-1 agonists (e.g., semaglutide, liraglutide): in type 2 diabetes with albuminuria - additional option to slow CKD progression

Dietary Counseling

• Protein restriction: 0.6-0.8 g/kg/day in pre-dialysis CKD (may slow GFR decline; avoid in malnourished patients)
• Sodium restriction: <2 g/day (reduces BP, edema, and potentiates RAAS blockade)
• Potassium restriction: <2 g/day if hyperkalemia (K >5.5 mEq/L)
• Phosphate restriction: limit high-phosphate foods (dairy, processed foods, nuts)

C. Managing Complications

Metabolic Acidosis

• Sodium bicarbonate 650 mg twice daily, titrated to serum bicarbonate target ~22-24 mEq/L
• Slows CKD progression independently
• Risk: sodium load may worsen fluid retention/hypertension

Hyperkalemia

• Mild (K 5.0-5.5): dietary restriction (<2 g/day), avoid K-sparing drugs
• Moderate-severe (K >5.5): pharmacologic treatment
  • Sodium zirconium cyclosilicate (Lokelma): fast-acting K+ binder; available for both acute and chronic management
  • Patiromer (Veltassa): calcium-matched potassium binder; for chronic hyperkalemia maintenance
  • Sodium polystyrene sulfonate (Kayexalate): older agent; less preferred
  • Emergency: Calcium gluconate (cardiac membrane stabilization), insulin + dextrose (K+ shift), loop diuretics

Anemia (Anemia of CKD)

• Replete iron before/alongside ESA therapy
• Target ferritin 200-500 ng/mL and TSAT 20-40% in non-dialysis CKD
• Oral iron: ferrous sulfate 325 mg 2-3 times/day (often inadequate due to GI absorption impairment by hepcidin)
• IV iron (preferred in dialysis patients on ESAs): ferric carboxymaltose, iron sucrose, low-molecular-weight iron dextran

• Start when Hgb <9-10 g/dL with symptoms; generally reserved for G4-G5
• Target Hgb: avoid levels >11.5 g/dL (TREAT trial: higher targets increase stroke and thrombosis risk)
• Epoetin alfa: 50-100 units/kg SC 3 times/week; or 10,000-20,000 units every other week for non-dialysis patients. Average maintenance 75 units/kg 3×/week. SC preferred (20-40% dose savings)
• Darbepoetin alfa: 0.45 μg/kg IV or SC once weekly, or 0.75 μg/kg every 2 weeks. Longer half-life (3× longer than epoetin alfa)
• ESA resistance: suspect in patients who do not respond to 12-week escalation; causes include iron deficiency, infection/inflammation, occult bleeding, folate deficiency, carnitine deficiency, hyperparathyroidism, aluminum toxicity, inadequate dialysis

• Roxadustat, daprodustat: oral agents that stabilize HIF → stimulate endogenous EPO production; also reduce hepcidin
• Approved in some countries; under review in others

Mineral and Bone Disease (CKD-MBD)

1. Phosphate restriction: dietary + oral phosphate binders
   • Calcium-based binders (calcium carbonate, calcium acetate): first-line; bind dietary phosphate in gut; avoid if Ca >10.2 mg/dL or PTH is suppressed (risk of vascular calcification)
   • Non-calcium binders:
     • Sevelamer hydrochloride/carbonate: also lowers LDL; safe in vascular calcification
     • Lanthanum carbonate: chewed with meals
     • Ferric citrate: also treats iron deficiency
     • Sucroferric oxyhydroxide: iron-based binder
2. Active Vitamin D supplementation:
   • Calcitriol (1,25-dihydroxyvitamin D): 0.25-0.5 μg orally daily or every other day, titrated to PTH/GFR
   • Paricalcitol, doxercalciferol: vitamin D analogues; less hypercalcemia risk
   • First correct 25-OH vitamin D deficiency with cholecalciferol/ergocalciferol before active vitamin D
3. Calcimimetics (dialysis patients with secondary hyperparathyroidism):
   • Cinacalcet 30 mg orally daily (titrate to 60-90-120-180 mg) - allosteric activator of calcium-sensing receptor → suppresses PTH
   • Etelcalcetide (IV, dialysis only)
4. Parathyroidectomy: for refractory tertiary hyperparathyroidism (subtotal or total + autotransplantation)

Cardiovascular Risk Reduction

• Statins: recommended to lower LDL and reduce cardiovascular events (similar benefit to non-CKD population, but start before dialysis; less clear benefit in dialysis)
• Blood pressure control: <130/80 mmHg
• Smoking cessation, physical activity, weight loss
• Aspirin: when indicated for cardiovascular disease; increased bleeding risk in CKD

Fluid and Edema Management

• Loop diuretics (furosemide): high doses often required due to impaired tubular secretion; can combine with thiazides for synergistic effect
• Salt restriction

D. Preparation for Renal Replacement Therapy (RRT)

• Nephrologist referral: GFR <30 (earlier if rapid decline, or complex management)
• Vascular access creation (AV fistula preferred over graft or catheter): 6-12 months before anticipated dialysis start
• Peritoneal dialysis catheter placement: 4-6 weeks before start
• Kidney transplant evaluation: should begin at GFR 20-25 to allow time for workup and listing

• Refractory hyperkalemia, acidosis, or fluid overload
• Uremic symptoms (encephalopathy, pericarditis, platelet dysfunction causing bleeding)
• GFR <10 regardless of symptoms (G5)
• GFR 10-15 with symptoms or nutritional failure

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8. Pharmacology Summary

Renoprotective Agents

Anemia Agents

Bone and Mineral Agents

Hyperkalemia Agents

Cardiovascular/BP Agents Used in CKD

Renal Replacement Therapy Modalities

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9. Prognosis

• CKD progression is measured by rate of GFR decline (slope of eGFR over time; normally ~1 mL/min/year after age 40)
• Risk of ESRD depends on stage, albuminuria, cause, and modifiable factors
• Patients with CKD have significantly increased risk of cardiovascular death compared to progression to ESRD - especially at G3-G4
• With optimal treatment (RAAS blockade, SGLT2 inhibitors, BP control), progression can be markedly slowed or halted
• AKI episodes accelerate CKD progression

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• Goldman-Cecil Medicine, International Edition (pp. 1333-1347)
• Brenner and Rector's The Kidney, 2-Volume Set (pp. 2378)
• Textbook of Family Medicine, 9th Edition (pp. 1192)
• Goodman & Gilman's Pharmacological Basis of Therapeutics (pp. 922)
• Katzung's Basic and Clinical Pharmacology, 16th Edition
• Tietz Textbook of Laboratory Medicine, 7th Edition

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Uraemia (Uremia)

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1. Definition

• Acute uremia: AKI reaching GFR <10-15 mL/min with failure to recover
• Chronic uremia: Advanced CKD (Stage G5, GFR <15 mL/min/1.73 m²) - end-stage renal disease (ESRD)
• Acute-on-chronic uremia: Acute decompensation of established CKD

• Ganong's Review of Medical Physiology, 26th Edition, p. 692
• Harrison's Principles of Internal Medicine, 22nd Edition
• Brenner and Rector's The Kidney, 2-Volume Set

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2. Types / Classification

A. By Temporal Pattern

B. By Underlying Renal Pathology

C. By Clinical Presentation (Severity)

• Pre-uremic state: Elevated BUN/creatinine, biochemical abnormalities, minimal or no symptoms
• Overt uremic syndrome: Full multi-system clinical syndrome with symptoms (GFR typically <10-15 mL/min)
• Uremic emergency: Life-threatening manifestations requiring emergency dialysis (uremic encephalopathy, pericarditis, uremic bleeding, severe hyperkalemia/acidosis)

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3. Causes

Primary Renal Causes

• Diabetic nephropathy (most common worldwide)
• IgA nephropathy
• Focal segmental glomerulosclerosis (FSGS)
• Lupus nephritis, ANCA vasculitis, Goodpasture disease
• Membranous nephropathy

• Hypertensive nephrosclerosis (second most common)
• Renovascular disease/renal artery stenosis
• Thrombotic microangiopathies (TTP, HUS, aHUS)
• Cholesterol atheroembolism

• Chronic pyelonephritis / reflux nephropathy
• Analgesic nephropathy (NSAIDs, phenacetin)
• Chronic drug nephrotoxicity (cyclosporine, lithium, aristolochic acid)
• Heavy metal toxicity (lead, cadmium)

• Autosomal dominant polycystic kidney disease (ADPKD)
• Alport syndrome

• Ischemic ATN
• Toxic ATN (aminoglycosides, contrast, cisplatin, myoglobin, hemoglobin)
• Rapidly progressive glomerulonephritis

Systemic Causes Affecting the Kidney

• Amyloidosis (AL/AA)
• Multiple myeloma / light-chain nephropathy
• Systemic infections (hepatitis B/C, HIV, TB - in developing countries)
• Sarcoidosis

Obstructive/Postrenal

• Bilateral ureteral obstruction (stones, retroperitoneal fibrosis, tumor)
• Bladder outlet obstruction (BPH, prostate/bladder/cervical cancer)
• Neurogenic bladder

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4. Pathophysiology

A. The Uremic Toxin Problem

Small-Molecule Uremic Toxins (<500 Da, water-soluble)

• Urea: Quantitatively the most abundant. BUN >180 mg/dL causes nausea, weakness, lethargy. At lower levels, serves more as a surrogate marker than a direct toxin.
• Creatinine: Not directly toxic even at very high concentrations; its metabolites methylguanidine (MG) and creatol are toxic
• Guanidines (guanidinosuccinic acid [GSA], methylguanidine): Derived from arginine. GSA inhibits platelets in vitro and stimulates nitric oxide generation → inhibits platelet adhesion. Guanidino compounds antagonize GABA receptors and are NMDA agonists → uremic encephalopathy and seizures
• Uric acid: Contributes to gout, vascular disease
• Phenols (phenol, p-cresol/p-cresyl sulfate): Disrupt cell membranes, impair immune cell function
• Oxalate: Contributes to soft tissue calcification
• Phosphate: Drives secondary hyperparathyroidism, vascular calcification, CKD-MBD

Middle Molecules (500 Da - 60 kDa)

• β2-Microglobulin (~11 kDa): Accumulates in long-term dialysis → deposits as amyloid fibrils in joints, carpal tunnel, bone (dialysis-related amyloidosis)
• Parathyroid hormone (PTH): Elevated in secondary hyperparathyroidism; contributes to encephalopathy (raises brain calcium), osteitis fibrosa cystica, pruritis
• FGF-23: Rises early; drives LV hypertrophy and cardiovascular risk
• Advanced glycosylation end products (AGEs): Vascular injury, inflammation
• Leptin, ghrelin, resistin: Adipokines elevated due to reduced renal clearance → insulin resistance, appetite dysregulation

Protein-Bound Solutes

• Indoxyl sulfate: Derived from intestinal tryptophan metabolism; cardiovascular toxin, promotes tubular fibrosis
• p-Cresyl sulfate: Endothelial toxicity, inflammation
• Asymmetric dimethylarginine (ADMA): Inhibits endothelial NO synthase → endothelial dysfunction, hypertension, accelerated cardiovascular disease; levels correlate with cerebrovascular complications

Low-Molecular-Weight Proteins Accumulating in Uremia

B. Loss of Renal Synthetic/Endocrine Functions

C. Pathophysiology of Key Uremic Manifestations

• Brenner and Rector's The Kidney, pp. 2368-2380
• Comprehensive Clinical Nephrology, 7th Edition, pp. 1197-1198

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5. Clinical Manifestations

Symptoms and Signs by System

Neurological (Uremic Encephalopathy)

• Mood swings, depression, anxiety
• Impaired concentration, loss of recent memory
• Insomnia, fatigue, apathy
• Hyperreflexia, tremor

• Asterixis (negative myoclonus - intermittent loss of muscle tone in anti-gravity muscles; elicited with outstretched hands, protruded tongue, or raised index finger)
• Myoclonus (activation of anti-gravity muscles, millisecond duration)
• Restless legs syndrome
• Sleep disturbances, altered sleep-wake cycle
• Peripheral neuropathy (stocking-glove distribution; dying-back axonal neuropathy)

• Delirium, psychosis
• Generalized seizures
• Coma → death if untreated

Cardiovascular

• Hypertension (most common; due to fluid retention and RAAS activation)
• Uremic pericarditis: chest pain (pleuritic character), pericardial friction rub; may progress to pericardial effusion or tamponade
• Heart failure / pulmonary edema (from fluid overload and hypertensive cardiomyopathy)
• LV hypertrophy (from hypertension and FGF-23)
• Accelerated atherosclerosis (coronary artery disease, stroke, PVD)
• Arrhythmias (from hyperkalemia)

Respiratory

• Pleurisy / uremic pleuritis: fibrinous pleuritis, exudative pleural effusion
• Kussmaul breathing: deep sighing respiration from metabolic acidosis
• Pulmonary edema (from fluid overload)
• "Uremic lung" (pulmonary edema from increased permeability, butterfly pattern on CXR)

Gastrointestinal

• Anorexia (earliest and most consistent GI symptom)
• Nausea, vomiting
• Uremic fetor: ammoniacal or urine-like breath odor (from urea converted to ammonia by salivary urease)
• Gastritis, peptic ulceration (increased gastrin production)
• GI bleeding (from platelet dysfunction, mucosal fragility)
• Diarrhea, constipation
• Hiccups (diaphragm irritation)

Hematological

• Normochromic, normocytic anemia (from EPO deficiency + shortened RBC survival + hepcidin-mediated iron sequestration)
• Platelet dysfunction (qualitative defect): prolonged bleeding time, bruising, epistaxis, gum bleeding, GI bleeding, menorrhagia. PT, aPTT, and platelet COUNT are usually normal.
• Shortened erythrocyte lifespan (from uremic toxin-induced membrane fragility)
• Lymphocyte and granulocyte dysfunction (impaired immune response, increased infection susceptibility)
• Thrombocytopenia may occur from dialysis membrane activation

Dermatological

• Pruritus (most distressing symptom; from phosphate deposition in skin, secondary hyperparathyroidism, mast cell proliferation, peripheral neuropathy)
• Uremic frost: white-yellow crystalline deposits on skin (urea crystallizing from sweat); seen in very severe uremia
• Sallow/yellow-grey pigmentation (from urochrome accumulation and anemia)
• Pruritic excoriations, dry skin (xerosis)
• Nail changes: half-and-half nails (Lindsay's nails) - proximal white, distal brown/pink band
• Pallor (anemia)
• Bruising, petechiae (from platelet dysfunction)

Musculoskeletal

• Renal osteodystrophy (umbrella term for CKD-MBD): bone pain, fractures
  • Osteitis fibrosa cystica: from high PTH → osteoclastic resorption
  • Osteomalacia: from calcitriol deficiency → defective bone mineralization
  • Adynamic bone disease: low PTH (from over-suppression) → low turnover
  • Osteoporosis: multifactorial
• Calciphylaxis (calcific uremic arteriolopathy): calcification of small arteries → ischemic skin necrosis; severe pain
• Dialysis-related amyloidosis: β2-microglobulin deposits → carpal tunnel syndrome, destructive arthropathy (in long-term dialysis patients)
• Myopathy, muscle weakness
• Muscle cramps (from electrolyte disturbances)

Endocrine/Metabolic

• Insulin resistance (glucose intolerance without overt diabetes)
• Dyslipidemia: hypertriglyceridemia (from impaired lipoprotein lipase)
• Secondary hyperparathyroidism (↓ calcitriol → ↑ PTH)
• Elevated prolactin → gonadal dysfunction: amenorrhea, impotence, infertility
• Altered thyroid metabolism
• Altered thyroxine metabolism (euthyroid sick-like picture)

Electrolyte/Acid-Base

• Hyperkalemia: life-threatening arrhythmias
• Metabolic acidosis: anion gap type (↑ sulfates, phosphates, urate) at advanced stages
• Hyperphosphatemia: secondary hyperparathyroidism, vascular calcification
• Hypocalcemia: from calcitriol deficiency and phosphate retention
• Sodium abnormalities: hypo- or hypernatremia depending on water balance
• Fluid overload: edema, pulmonary edema, hypertension

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6. Diagnostic Approach

Confirming Uremia

• Symptoms: anorexia, nausea/vomiting, fatigue, pruritus, edema, oliguria, confusion, restless legs
• History of CKD, diabetes, hypertension, nephrotoxin exposure
• Drug history (nephrotoxic medications)
• Family history (ADPKD, Alport syndrome)

• Pallor, sallow complexion, uremic frost (late)
• Pruritic excoriations, half-and-half nails
• Asterixis, altered consciousness, seizures
• Pericardial friction rub
• Kussmaul breathing
• Peripheral edema, pulmonary edema signs (raised JVP, crepitations)
• Peripheral neuropathy signs

Laboratory Investigations

• HbA1c, fasting glucose: diabetic nephropathy
• ANA, anti-dsDNA, ANCA, anti-GBM: autoimmune/vasculitis
• SPEP, UPEP, free light chains: myeloma
• Complement C3/C4: lupus, MPGN
• Hepatitis B/C, HIV serology
• 25-OH vitamin D + 1,25-OH vitamin D: bone disease

• Renal ultrasound (essential): kidney size (small + echogenic = CKD; large = acute or infiltrative disease), cortical thickness, hydronephrosis (postrenal), cysts (ADPKD)
• CXR: cardiomegaly, pulmonary edema, "bat-wing" perihilar edema, pleural effusion, pericardial effusion
• ECG: peaked T waves, wide QRS, sine wave pattern (hyperkalemia); low-voltage/electrical alternans (pericardial effusion)
• Echocardiography: LV hypertrophy, pericardial effusion, wall motion abnormalities

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7. Management

A. Treat Underlying Cause

• Remove nephrotoxins / offending drugs
• Aggressive blood pressure control (target <130/80 mmHg)
• Glycemic control in diabetic CKD
• Immunosuppression for GN/vasculitis
• Relieve obstruction (catheter, nephrostomy, stent)
• Volume resuscitation for prerenal component

B. Conservative Management of Uremic Complications

• Protein restriction: 0.6-0.8 g/kg/day (reduces nitrogenous waste generation and delays dialysis need; avoid in malnourished patients)
• Sodium restriction: <2 g/day
• Potassium restriction: <2 g/day if hyperkalemia
• Phosphate restriction: avoid high-phosphate foods (dairy, processed meats, nuts, cola)
• Adequate caloric intake: 30-35 kcal/kg/day to prevent catabolism
• Fluid restriction: if oliguric

• Dietary restriction
• Sodium zirconium cyclosilicate (Lokelma) or patiromer for chronic management
• Emergency: calcium gluconate IV (cardiac membrane stabilization), insulin + dextrose (10 U + 50 mL 50% dextrose IV), sodium bicarbonate, loop diuretics
• Dialysis if refractory

• Sodium bicarbonate 650 mg orally twice daily, titrated to serum bicarbonate target 22-24 mEq/L
• Slows CKD progression as well as treating acidosis
• Calcium carbonate (phosphate binder) also provides alkali

• Dietary phosphate restriction
• Phosphate binders (calcium carbonate, sevelamer, lanthanum carbonate)
• Active vitamin D (calcitriol 0.25-0.5 μg/day)
• Calcimimetics (cinacalcet) for dialysis patients with secondary hyperparathyroidism
• Parathyroidectomy for tertiary hyperparathyroidism refractory to medical treatment

• Adequate dialysis dose
• Control of hyperphosphatemia/hyperparathyroidism
• Topical emollients, topical capsaicin
• Gabapentin (use with caution due to accumulation in renal failure)
• Naltrexone (opioid antagonist) or nalfurafine (κ-opioid agonist - approved in some countries)
• UVB phototherapy
• Antihistamines (limited evidence)

• Initiate/optimize dialysis (primary treatment)
• Treat hyperkalemia, acidosis, hyponatremia
• Avoid/dose-adjust neurotoxic drugs (meperidine, gabapentin, metoclopramide, acyclovir, certain antibiotics)
• Seizure management with appropriate AEDs (phenobarbital, levetiracetam preferred; phenytoin absorption altered in uremia)
• Dialysis reverses encephalopathy in most patients

C. Uremic Bleeding (Pharmacological Management)

D. Cardiovascular Management

• Antihypertensives: RAAS blockade (ACEi/ARB) as first-line; additional agents as needed
• Diuretics: Loop diuretics (furosemide, high doses often required) for volume control/edema
• Uremic pericarditis: Intensify dialysis (primary treatment); NSAIDs/corticosteroids if dialysis inadequate; pericardiocentesis for tamponade; pericardiectomy for constrictive pericarditis
• Statins: Reduce cardiovascular mortality (in pre-dialysis CKD; less clear benefit in dialysis)

E. Anemia Management

• Erythropoiesis-stimulating agents (ESAs): Epoetin alfa 50-100 U/kg SC 3×/week or darbepoetin alfa 0.45 μg/kg once weekly; target Hgb 10-11.5 g/dL (avoid >11.5 g/dL due to thrombosis/stroke risk)
• Iron supplementation: Iron repletion before/with ESAs; IV iron preferred in dialysis patients (ferric carboxymaltose, iron sucrose)
• HIF-PHIs (roxadustat, daprodustat): Oral agents stimulating endogenous EPO synthesis; approved in EU/Asia/Japan

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8. Pharmacology Summary

Renal Replacement Therapy (RRT) - Definitive Treatment

• Acidosis: pH <7.1 or refractory metabolic acidosis
• Electrolytes: Refractory hyperkalemia (K+ >6.5 mEq/L or with ECG changes)
• Intoxication: Toxin removal (methanol, ethylene glycol, salicylates, metformin, lithium, barbiturates, valproate in overdose)
• Overload: Refractory pulmonary edema/volume overload
• Uremia: Uremic encephalopathy (asterixis, seizures, coma), uremic pericarditis, uremic bleeding unresponsive to medical management, BUN >100 mg/dL without clinical recovery

• Kt/V urea ≥1.4 per session (IHD) - measures urea clearance per session
• Inadequate dialysis → persistent uremic symptoms (anorexia, malaise, pericarditis, fluid overload)

Key Drug Dosing Adjustments in Uremia

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9. Prognosis

• Acute uremia from AKI: Prognosis depends on severity of underlying cause and timeliness of treatment. Many cases are reversible with appropriate management.
• Chronic uremia (ESRD): Without RRT, chronic uremia is fatal, typically within weeks to months.
• With hemodialysis: 5-year survival rates ~40-50% (varies widely with age, diabetes, cardiovascular status)
• With kidney transplantation: Best outcomes; 5-year graft survival ~80%; life expectancy near-normal in young recipients
• Quality of life consistently improves with transplantation versus dialysis
• Cardiovascular disease is the leading cause of death in ESRD patients on dialysis (~50% of deaths)

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• Brenner and Rector's The Kidney, 2-Volume Set (pp. 2368-2382)
• Comprehensive Clinical Nephrology, 7th Edition (pp. 1197-1198)
• Harrison's Principles of Internal Medicine, 22nd Edition
• Ganong's Review of Medical Physiology, 26th Edition (p. 692)
• Henry's Clinical Diagnosis and Management by Laboratory Methods (p. 976)
• Tintinalli's Emergency Medicine: A Comprehensive Study (p. 760-761)
• The Washington Manual of Medical Therapeutics (pp. 1132-1145)
• Goldman-Cecil Medicine, International Edition

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PART 1: Benign Prostatic Hyperplasia (BPH)

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1. Definition

• Goldman-Cecil Medicine, International Edition, p. 1316
• Sabiston Textbook of Surgery, p. 2824
• Robbins & Kumar Basic Pathology

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2. Types / Classification

By Symptom Type (LUTS Classification)

By Severity (International Prostate Symptom Score - IPSS)

By Tissue Composition (Histological)

• Stromal-predominant BPH (fibromuscular): responds better to alpha-blockers (smooth muscle relaxation)
• Glandular-predominant BPH: responds better to 5α-reductase inhibitors
• Mixed stromal-glandular BPH: combination therapy most effective

By Complication Status

• Uncomplicated BPH: LUTS without complications
• Complicated BPH: with urinary retention, UTI, bladder stones, hydronephrosis/azotemia, hematuria

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3. Causes and Risk Factors

Primary Cause

• Functioning testes (BPH does not occur in men castrated before puberty)
• Androgens (BPH does not develop with genetic diseases that block androgen activity)
• Age (the only non-modifiable risk factor)

Hormonal Pathogenesis

• Dihydrotestosterone (DHT): the ultimate prostatic growth mediator; 10× more potent than testosterone. Synthesized from testosterone in the prostate by 5α-reductase type 2.
• Estrogen effect: With aging, testosterone declines while estrogen remains unchanged or increases (via peripheral aromatization). Estrogens act synergistically with DHT to drive growth of epithelial and stromal cells (which express estrogen receptors).

Risk Factors

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4. Pathophysiology

Molecular Mechanism of Prostatic Growth

1. Testosterone enters prostatic stromal and epithelial cells
2. 5α-reductase type 2 converts testosterone → DHT (10× more potent)
3. DHT binds nuclear androgen receptors (ARs) → activates gene expression
4. DHT-induced growth factors (e.g., EGF, KGF/FGF-7, IGF-1, TGF-β):
   • Increase stromal cell proliferation
   • Decrease epithelial cell apoptosis (shift in proliferation-apoptosis equilibrium)
5. With aging: ↓ testosterone, unchanged/↑ estrogen → estrogen synergizes with DHT via AR upregulation → continued growth

Anatomical Consequences

Mechanisms of LUTS

• Enlarged prostate mass compresses urethra → increased urethral resistance → ↓ urine flow → bladder hypertrophy (detrusor muscle thickening)

• Sympathetic α1-adrenergic receptors (especially α1A subtype) in prostatic stroma and bladder neck → smooth muscle contraction → functional obstruction
• This component is reversible and the target of α-blocker therapy

• Chronically elevated intravesical pressure → bladder wall hypertrophy → trabeculation → diverticula
• Overactive bladder (OAB): Bladder hypertrophy leads to increased detrusor instability → urgency, frequency, nocturia
• Incomplete emptying → post-void residual urine → increased UTI risk
• With long-standing obstruction: bladder decompensation → hypotonicity, chronic retention, overflow incontinence, hydronephrosis

Complications of Untreated BPH

• Acute urinary retention (AUR): sudden inability to void; precipitated by sympathomimetics (cold remedies), anticholinergics, postponing micturition
• Chronic urinary retention: painless high-volume retention; risk of renal failure
• UTI / cystitis: residual urine provides bacterial culture medium
• Bladder calculi: from stasis, infection, altered urine composition
• Hematuria: from increased prostatic vascularity; can be gross
• Hydronephrosis and CKD/azotemia: from obstructive uropathy
• Robbins & Kumar Basic Pathology, p. 659
• Campbell Walsh Wein Urology

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5. Diagnostic Approach

History

• Document LUTS type (storage vs. voiding vs. post-void)
• IPSS questionnaire: quantify symptom severity; includes QoL question
• Duration of symptoms, rate of progression
• Medication history (alpha-stimulants, anticholinergics, diuretics - can worsen LUTS)
• Sexual function history (BPH/LUTS commonly co-exist with ED)
• Prior urological history (catheterization, STDs, urethral stricture)
• Medical history (neurologic disease, diabetes - can cause similar LUTS)

Physical Examination

• Digital Rectal Examination (DRE): Size (normal ~20 mL = size of walnut); consistency (BPH = soft/rubbery, uniform; cancer = hard/nodular); median sulcus (present in BPH, absent in cancer)
• Focused neurological exam: exclude neurogenic bladder (tone, perianal sensation, bulbocavernosus reflex)
• Abdominal palpation: palpable bladder (retention), flank tenderness (hydronephrosis/UTI)

Laboratory Tests

Urological Investigations

AUA/IPSS Management Algorithm

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6. Management

A. Watchful Waiting (Active Surveillance)

• Lifestyle and behavioral modifications (see below)
• Annual reassessment with IPSS, PVR, uroflowmetry
• Appropriate for patients who are not bothered by their symptoms

• Reduce evening fluid intake (limit after 6 PM)
• Avoid caffeine and alcohol (irritants → increase frequency/urgency)
• Bladder training (timed voiding, urgency suppression techniques)
• Double voiding (void, wait a few minutes, void again)
• Avoid constipation (worsen BOO)
• Weight loss
• Review medications that worsen LUTS (decongestants/alpha-stimulants, anticholinergics, diuretics)

B. Surgical Indications (Absolute)

• Acute urinary retention (failed voiding trial after catheter removal)
• Recurrent UTIs attributed to BPH
• Bladder calculi from BOO
• Gross hematuria recurrent from BPH
• Azotemia/hydronephrosis from obstructive uropathy
• Bladder diverticula causing complications

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7. Pharmacology

First-line: Alpha-1 Adrenergic Receptor Blockers (α1-Blockers)

Second-line: 5α-Reductase Inhibitors (5ARIs)

Combination Therapy (α1-Blocker + 5ARI)

• Tamsulosin + dutasteride (Jalyn): fixed-dose combination
• Provides rapid symptom relief (from α-blocker) + long-term disease modification (from 5ARI)

Phosphodiesterase Type 5 Inhibitors (PDE5 Inhibitors)

• Tadalafil (Cialis) 5 mg daily: FDA-approved for both BPH/LUTS and ED. Well-tolerated. Contraindicated with nitrates.
• Particularly useful in men with both BPH and ED (very common co-morbidity)

Anticholinergic Agents / Beta-3 Agonists (for OAB/Storage Symptoms)

• Solifenacin, oxybutynin, tolterodine, fesoterodine: Antimuscarinics; block M2/M3 receptors in detrusor → reduce involuntary contractions. Use with caution: can precipitate urinary retention if PVR >200 mL.
• Mirabegron (beta-3 agonist): Activates β3-adrenergic receptors → detrusor relaxation during filling; safer than antimuscarinics (less retention risk); can be combined with anticholinergics.

Phytotherapy (Herbal)

• Saw palmetto (Serenoa repens): widely used; mechanism unclear; conflicting evidence from RCTs; not strongly recommended in AUA guidelines
• Beta-sitosterol, Pygeum africanum: some benefit in small studies; limited evidence

Surgical Options

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• Goldman-Cecil Medicine, International Edition (pp. 1316-1318)
• Sabiston Textbook of Surgery, 21st Edition (pp. 2824-2826)
• Campbell Walsh Wein Urology, 3-Volume Set
• Robbins & Kumar Basic Pathology (p. 659)
• Textbook of Family Medicine, 9th Edition

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PART 2: Impotence / Erectile Dysfunction (ED)

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1. Definition

• Loss of libido (decreased sexual desire - primarily hormonal/psychological)
• Ejaculatory disorders (premature ejaculation, anejaculation, retrograde ejaculation)
• Orgasmic dysfunction

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2. Epidemiology

• 10-15% of all adult American men
• In one landmark study (MMAS - Massachusetts Male Aging Study): 52% of men aged 40-70 years experienced some degree of ED
• Prevalence increases dramatically with age: ~40% at age 40; ~70% at age 70
• Higher prevalence in: type 2 diabetes mellitus, post-radical prostatectomy, cardiovascular disease, hypertension, depression

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3. Types / Classification

A. By Etiology

B. By Degree of Severity

• Mild: Occasional difficulty; erections usually adequate
• Moderate: Frequent but not always inadequate erections
• Severe (complete ED): Inability to achieve/maintain erection in virtually all attempts

C. By Origin

• Primary ED: Never able to achieve erection (rare; usually psychological or severe organic)
• Secondary ED: Acquired after a period of normal function (most common)

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4. Causes

Vasculogenic (Most Common Organic Cause)

• Atherosclerosis of internal pudendal/cavernous arteries (shares pathophysiology with cardiovascular disease)
• Risk factors: hypertension, diabetes, hyperlipidemia, smoking, obesity
• Pelvic irradiation

• Inability of corporeal smooth muscle to relax adequately → failure of venous compression
• Associated with Peyronie's disease, aging, trauma

Neurogenic

• Central causes: Parkinson's disease, Alzheimer's, multiple sclerosis, cerebrovascular disease, spinal cord injury, epilepsy
• Peripheral causes: Diabetic autonomic neuropathy (most common), radical prostatectomy/cystectomy (nerve damage to neurovascular bundles), pelvic surgery, urethral trauma
• Nerve damage from surgery is particularly common: prostatectomy, TURP, rectal surgery, aortoiliac surgery

Endocrine/Hormonal

• Hypogonadism (primary or secondary): ↓ testosterone → ↓ libido + ED; caused by Klinefelter syndrome, orchitis, pituitary tumors, aging
• Hyperprolactinemia: Elevated prolactin suppresses GnRH → ↓ LH → ↓ testosterone → ED (occurs in <2% of ED cases)
• Hyperthyroidism / Hypothyroidism
• Diabetes mellitus: Multiple mechanisms - vasculopathy, neuropathy, endothelial dysfunction, psychological factors

Psychogenic

• Performance anxiety (most common psychogenic cause)
• Depression (strongly associated; also worsened by antidepressant therapy)
• Anxiety disorders
• Relationship problems / partner conflict
• Grief, stress, PTSD
• Sexual identity issues
• History of sexual abuse or trauma

• Psychogenic: Sudden onset, situational (ED with certain partners but not others), normal nocturnal/early morning erections, young age, identifiable psychosocial precipitant
• Organic: Gradual onset, consistent regardless of situation, absent nocturnal erections, older age, vascular/neurological risk factors

Drug-Induced (up to 25% of ED cases)

Systemic Disease

• Cardiovascular disease (endothelial dysfunction)
• CKD/uremia (elevated prolactin, hypogonadism)
• Liver cirrhosis (↑ estrogen, ↓ testosterone)
• Chronic pulmonary disease (hypoxia)
• HIV infection (50-53% prevalence of ED in HIV-positive men, even in young men; worsened by HAART)

Aging

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5. Pathophysiology

Normal Physiology of Erection

1. Sexual stimulation (tactile, visual, psychogenic) → activation of parasympathetic (S2-S4) and NANC nerve fibers in the neurovascular bundles of the cavernous nerve
2. NANC nerve terminals and penile endothelium release nitric oxide (NO)
3. NO activates soluble guanylate cyclase → converts GTP → cyclic GMP (cGMP)
4. cGMP activates protein kinase G → phosphorylates K+ channels and Ca2+ channels → smooth muscle relaxation in corpora cavernosa and penile arterioles
5. Relaxed smooth muscle → dilation of cavernous arteries and helicine arteries → increased blood inflow to lacunar spaces (sinusoids)
6. Tumescence: Engorgement of cavernosa → passive venous compression of subtunica venules against the tunica albuginea (veno-occlusive mechanism) → erection maintained
7. After ejaculation: sympathetic activation → norepinephrine → ↑ intracellular Ca2+ → smooth muscle contraction → detumescence. PDE5 degrades cGMP → also contributes to detumescence

Pathophysiologic Mechanisms of ED

• Risk factors (DM, HTN, smoking, dyslipidemia) → oxidative stress → ↓ NO bioavailability → impaired smooth muscle relaxation → failure to fill cavernosal sinusoids
• Penile vasculature is an early sentinel of systemic vascular disease (penile arteries are smaller, so atherosclerosis manifests earlier there than in coronary or cerebral vessels - explaining the lag between ED and symptomatic cardiac disease)

• Aging, pelvic nerve damage (surgery) → ↓ NO release → impaired erection initiation

• Failure of corporeal smooth muscle relaxation → sinusoids not fully engorged → subtunica veins not compressed → venous outflow continues → failure to maintain erection

• Testosterone has permissive role in NO synthase expression and penile tissue health; profound hypogonadism → decreased NO synthase → structural changes in cavernosa
• Hyperprolactinemia suppresses hypothalamic GnRH → ↓ LH/FSH → ↓ testosterone

• Loss of cavernous nerve input (from radical prostatectomy, diabetes, spinal cord disease) → no NO release initiated → no erection despite intact vascular mechanism
• Recovery after nerve-sparing prostatectomy takes 12-18 months; PDE5 inhibitors aid recovery

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6. Diagnostic Approach

History

• Sexual history: Onset (sudden vs. gradual), duration, situational nature (with all partners/situations or selective?), presence of nocturnal erections, libido, ejaculatory function, relationship factors
• SHIM / IIEF-5 (Sexual Health Inventory for Men / International Index of Erectile Function): 5-question validated questionnaire; scores 5-7 = severe, 8-11 = moderate, 12-16 = mild-moderate, 17-21 = mild, 22-25 = no ED
• Medical history: DM, CVD, hypertension, hyperlipidemia, neurological disease, pelvic surgery/radiation, trauma
• Drug history: All medications, recreational drugs, alcohol, tobacco
• Psychosocial history: Stress, depression, anxiety, relationship status, past sexual experiences

Physical Examination

• Cardiovascular: BP, peripheral pulses, bruits (aortoiliac occlusive disease can present as ED + bilateral buttock claudication - Leriche syndrome)
• Genital exam: Penile abnormalities (Peyronie's plaques), testicular size (hypogonadism = small/soft testes), secondary sexual characteristics
• Neurological: Perianal sensation, bulbocavernosus reflex, lower extremity DTRs
• Endocrine: Signs of hypogonadism (gynecomastia, reduced body hair, small testes), thyroid examination

Laboratory Tests

Specialized Tests (Second-line, as needed)

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7. Management

Step 1: Lifestyle Modification and Risk Factor Management

• Weight loss (obesity: insulin resistance → ↓ testosterone, endothelial dysfunction; weight loss improves ED in obese patients)
• Smoking cessation
• Reduce alcohol intake
• Regular aerobic exercise (improves endothelial function)
• Optimize diabetes, hypertension, hyperlipidemia control
• Stop or switch offending medications where possible (e.g., switch from beta-blocker to amlodipine; switch from SSRI to bupropion)
• Psychosexual counseling (alone or combined with pharmacotherapy)

Step 2: Pharmacotherapy

First-line: PDE5 Inhibitors

• Concurrent use of organic nitrates (nitroglycerin, isosorbide mono/dinitrate, amyl nitrite/poppers) - severe potentially fatal hypotension
• Severe cardiovascular disease where sexual activity is inadvisable
• Recent (<6 months) myocardial infarction, stroke, life-threatening arrhythmia, angina, severe hypotension/hypertension, cardiac failure
• Retinitis pigmentosa

Hormonal Therapy

• Testosterone replacement therapy (TRT):
  • Intramuscular testosterone cypionate/enanthate: 150-200 mg IM every 2-3 weeks
  • Testosterone gel (1-2%): 50-100 mg topically daily
  • Testosterone patches: 5-10 mg/day
  • Subcutaneous testosterone pellets
• Caution: Absolute contraindication in prostate cancer and breast cancer; use with caution in polycythemia, severe BPH, sleep apnea
• Treat concomitant conditions: hyperprolactinemia (bromocriptine/cabergoline), hypothyroidism (levothyroxine)

Step 3: Second-line - Local Therapies

Intracavernosal Injection (ICI) Therapy

Intraurethral Alprostadil (MUSE - Medicated Urethral System for Erection)

• Alprostadil pellet inserted into urethra via applicator
• Dose: 125-1000 μg
• Absorbed through urethral mucosa into corpus spongiosum → diffuses to corpora cavernosa
• Success rate ~40-65%
• Side effects: urethral burning/pain, hypotension, dizziness; priapism less common than ICI
• Advantage: Non-injectable; option for needle-phobic patients

Vacuum Erection Device (VED / Penile Pump)

• External vacuum device draws blood into corpora → constriction band applied at base to maintain erection
• Non-pharmacological; useful especially in post-prostatectomy, anticoagulated patients
• Success rate ~60-70%
• Side effects: Ecchymosis, petechiae, numbness, cold/dusky erection, pain, ejaculatory difficulties from constriction ring

Step 4: Surgical Treatment

Penile Prosthesis (Implant) - Gold Standard for Refractory ED

• Patient satisfaction: 85-90% for inflatable prostheses
• Complications: Infection (2-3%; devastating; requires removal), mechanical failure, erosion, migration

Penile Vascular Surgery

• Penile arterial revascularization: For young men (<55 yr) with focal arteriogenic ED from perineal/pelvic trauma (bicycle, straddle injury)
• Venous ligation: For venous leakage; poor long-term results; rarely performed

Psychological / Psychosexual Therapy

• Sex therapy and couples therapy: For psychogenic ED or psychogenic component
• Cognitive-behavioral therapy (CBT)
• Treatment of depression (note: many antidepressants worsen ED; bupropion + mirtazapine have least sexual side effects)
• Combination with PDE5 inhibitors improves outcomes vs. either alone

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8. Pharmacology Summary

PDE5 Inhibitor Comparison Table

ED Pharmacotherapy Algorithm

1. First-line: PDE5 inhibitor (sildenafil 50 mg or tadalafil 10 mg prn) + lifestyle modification
2. Hypogonadism confirmed: Add testosterone replacement
3. PDE5 inhibitor failure: Check compliance, optimize dose, address contributing factors; try alternative PDE5 inhibitor
4. Second-line: ICI (alprostadil or trimix) OR MUSE OR vacuum erection device
5. Refractory: Penile prosthesis

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• Goldman-Cecil Medicine, International Edition (pp. 2542-2543)
• Textbook of Family Medicine, 9th Edition (pp. 1193-1194)
• Campbell Walsh Wein Urology, 3-Volume Set (pp. 2130)
• Kaplan & Sadock's Comprehensive Textbook of Psychiatry (pp. 6140-6141)
• Sabiston Textbook of Surgery, 21st Edition

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CARDIOVASCULAR DISEASES: Comprehensive Reference

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1. CONGENITAL HEART DISEASE (CHD)

Definition

Types / Classification

A. Acyanotic CHD (Left-to-Right Shunts / Obstruction)

B. Cyanotic CHD ("Five Ts" + more) - Right-to-Left Shunts

Causes

• Genetic (10%): Trisomy 21 (Down - AVSD), Turner syndrome (coarctation, bicuspid aortic valve), Noonan syndrome (pulmonary stenosis), DiGeorge syndrome (22q11 deletion - truncus arteriosus, ToF), Marfan syndrome (aortic dilatation)
• VACTERL association: Vertebral anomalies, Anal atresia, Cardiac defects, Tracheoesophageal fistula, Esophageal atresia, Renal anomalies, Limb anomalies
• Teratogens: Rubella (PDA, pulmonary stenosis), thalidomide, alcohol (fetal alcohol syndrome), retinoic acid, phenytoin, lithium (Ebstein)
• Maternal DM: Transposition, VSD, hypertrophic cardiomyopathy
• Isolated embryological malformation (90%)

Pathophysiology

Left-to-Right Shunts (Acyanotic)

Right-to-Left Shunts (Cyanotic)

Diagnostic Approach

Management and Pharmacology

• Prostaglandin E1 (alprostadil): Maintains patent ductus arteriosus in duct-dependent lesions (TGA, pulmonary atresia, hypoplastic left heart syndrome) - 0.05-0.1 μg/kg/min IV infusion
• Indomethacin (COX inhibitor) or ibuprofen: Close PDA in premature infants (inhibit prostaglandin synthesis)
• Propranolol (oral): Reduces RVOT obstruction in TOF; reduces tet spell frequency
• Diuretics (furosemide): Manage heart failure from large shunts
• Digoxin: For heart failure in infants with large L→R shunts

• VSD/ASD: Surgical patch or device closure (catheter-based); ASD: often transvenous device closure (Amplatzer device)
• TOF: Complete repair (patch VSD + RVOT reconstruction) usually at 3-6 months
• TGA: Arterial switch operation (Jatene procedure) in first 2 weeks of life
• Coarctation: Balloon dilation ± stenting OR surgical resection
• Eisenmenger syndrome: Pulmonary vasodilators (bosentan, sildenafil), anticoagulation, avoid vasodilators that drop SVR; heart-lung transplantation is definitive

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2. COR PULMONALE

Definition

Types

• Acute cor pulmonale: RV dilation with little or no hypertrophy; e.g., massive pulmonary embolism (sudden severe RV pressure overload; if embolism causes sudden death, heart may be normal-sized)
• Chronic cor pulmonale: RV hypertrophy + dilation from sustained pulmonary hypertension; e.g., COPD, pulmonary fibrosis; RV wall thickness may equal or exceed LV thickness

Causes

Pathophysiology

1. Primary lung disease → alveolar hypoxia (most important mechanism) + destruction of alveolar capillary bed + lung hyperinflation + polycythemia-related ↑ blood viscosity
2. Hypoxic pulmonary vasoconstriction (HPV): Hypoxia → vasoconstriction of pulmonary arterioles (Euler-Liljestrand reflex) → ↑ pulmonary vascular resistance (PVR)
3. Persistent HPV + structural remodeling (smooth muscle hypertrophy, intimal thickening of pulmonary arteries) → sustained pulmonary arterial hypertension (PAH)
4. RV must overcome elevated PVR → RV pressure overload → concentric RV hypertrophy (Laplace's law: increased wall thickness normalizes wall stress)
5. Eventually RV dilatation → tricuspid regurgitation → right-sided heart failure (raised JVP, peripheral edema, hepatomegaly, ascites)
6. Distortion of LV shape by enlarged RV → interventricular septal shift → impaired LV filling → reduced cardiac output

Clinical Features / Diagnosis

• Elevated JVP with prominent 'a' and 'v' waves
• Right ventricular heave/parasternal lift
• Loud P2 (loud pulmonary component of S2)
• Tricuspid regurgitation murmur (pansystolic at LLSB, increases with inspiration)
• Peripheral edema, ascites, hepatomegaly
• Cyanosis (central, from hypoxemia)

Management and Pharmacology

• COPD: Bronchodilators, pulmonary rehabilitation, smoking cessation
• PE: Anticoagulation (LMWH/DOAC), thrombolysis if hemodynamically unstable

• PaO₂ <55 mmHg at rest, or <60 mmHg with polycythemia or cor pulmonale
• ≥15 hours/day; reduces pulmonary vasoconstriction and mortality

• Phosphodiesterase-5 inhibitors: Sildenafil 20 mg TID, tadalafil 40 mg OD → ↑ cGMP → pulmonary vasodilation
• Endothelin receptor antagonists: Bosentan 62.5-125 mg BD, ambrisentan, macitentan → block ET-1 mediated vasoconstriction; liver toxicity monitoring required
• Prostacyclin analogues: Epoprostenol (IV continuous infusion - gold standard for severe PAH), treprostinil (SC/inhaled/oral), iloprost (inhaled); potent pulmonary vasodilators; prostacyclin analogs
• Riociguat: sGC stimulator; for PAH and chronic thromboembolic PH (CTEPH)
• Selexipag: Selective IP receptor agonist; oral; reduces PAH progression

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3. ISCHEMIC HEART DISEASE (IHD) / CORONARY ARTERY DISEASE

Definition

Types

Causes / Risk Factors

Pathophysiology

1. Endothelial injury (from HTN, smoking, dyslipidemia, shear stress) → endothelial dysfunction
2. LDL enters intima → oxidized LDL → monocyte recruitment → foam cell formation → fatty streak
3. Smooth muscle cell migration + proliferation + extracellular matrix → fibrous plaque (atheroma)
4. Vulnerable plaque = large lipid core + thin fibrous cap → prone to rupture
5. Plaque rupture/erosion → exposure of thrombogenic material → platelet aggregation + thrombus formation → lumen occlusion → acute MI

• Seconds: ATP depletion
• <2 minutes: Loss of contractility
• 10 minutes: ATP reduced to 50%
• 20-40 minutes: Irreversible cell injury (point of no return)
• Ischemia progresses from subendocardium outward (wavefront phenomenon)

• LAD → anterior wall LV + anterior 2/3 septum + apex (most common; "widowmaker")
• RCA → inferior wall LV + posterior wall + right ventricle + SA/AV nodes
• LCx → lateral wall LV

• Contractile dysfunction → cardiogenic shock (>40% LV lost)
• Papillary muscle dysfunction → acute mitral regurgitation
• Free wall rupture → hemopericardium/tamponade (2-7 days)
• Ventricular septal rupture → acute VSD with shunt
• Ventricular aneurysm → mural thrombus, arrhythmias
• Post-MI pericarditis (fibrinous; 1-3 days) / Dressler syndrome (autoimmune; weeks later)
• Arrhythmias (VF in first hour, complete heart block with inferior MI)

Diagnostic Approach

Management and Pharmacology

Acute STEMI (Time = Muscle)

Antiplatelet/Anticoagulant Therapy

Long-term Medications Post-MI

• Calcium channel blockers (amlodipine, diltiazem): Vasodilation; for stable angina when beta-blockers contraindicated
• Ranolazine: Late Na+ channel blocker → ↓ intracellular Ca²⁺ → ↓ diastolic tension; for stable angina
• Nicorandil: K+ATP channel opener + nitrate-like; reduces angina frequency

• PCI + stenting: Drug-eluting stents (DES) preferred; dual antiplatelet therapy required ≥12 months
• CABG: For left main disease, 3-vessel disease, diabetes + multivessel disease, failed PCI, severely reduced EF

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4. RHD - RHEUMATIC HEART DISEASE / VALVULAR DISEASES

Definition

Types of Valvular Lesions

Mitral Stenosis (MS)

• Most common cause: RHD (nearly all cases)
• Pathophysiology: Leaflet thickening/fusion → narrowed mitral orifice → ↑ left atrial pressure → pulmonary hypertension → RV failure; LA dilation → AF risk
• Normal valve area: 4-6 cm²; Mild MS: 1.5-2.0 cm²; Moderate: 1.0-1.5 cm²; Severe: <1.0 cm²
• Symptoms: Dyspnea, orthopnea, hemoptysis (from pulmonary HTN), palpitations (AF), systemic emboli
• Exam: Mid-diastolic rumble at apex (low-pitched with opening snap); loud S1; opening snap (OS) closer to S2 = more severe
• ECG: P-mitrale (bifid P in II), LA enlargement; RVH with AF
• CXR: "Double shadow" (LA enlargement), straightening of left heart border, upper lobe blood diversion
• Echo: Domed mitral leaflets, reduced valve area (pressure half-time method), LA enlargement
• Management: Rate control in AF (beta-blockers, digoxin, CCB); anticoagulation (warfarin) for AF/emboli; diuretics; Percutaneous Mitral Balloon Commissurotomy (PMBC) for pliable valves; Mitral valve repair/replacement (metallic or bioprosthetic)

Mitral Regurgitation (MR)

• Causes: RHD, mitral valve prolapse (most common in developed countries), ischemic (papillary muscle dysfunction), IE, connective tissue disorders, dilated cardiomyopathy, rupture of chordae tendineae
• Pathophysiology: Regurgitant volume into LA → LA dilation → ↑ LVEDV (volume overload) → eccentric LV hypertrophy → eventually LV dysfunction
• Acute MR (chordal rupture, papillary muscle rupture post-MI): Pulmonary edema, cardiogenic shock
• Exam: Holosystolic murmur at apex radiating to axilla; displaced apex; soft S1; S3 (volume overload)
• Management: Vasodilators (ACEi/ARBs, nifedipine) for chronic; Surgery (repair > replacement) when LVEF <60% or LVESD >40 mm

Aortic Stenosis (AS)

• Causes: Calcific/degenerative (most common in elderly), bicuspid aortic valve (young), RHD
• Pathophysiology: Obstruction of LV outflow → ↑ LV systolic pressure → concentric LV hypertrophy → eventually LV failure; fixed CO leads to the classic triad when severe
• Classic Triad of Severe AS: Syncope, angina, dyspnea/heart failure; average survival after each: 3 yr, 5 yr, 2 yr
• Exam: Harsh ejection systolic murmur at aortic area (2R ICS) radiating to carotids; soft/absent A2; slow-rising pulse (pulsus parvus et tardus); paradoxical splitting of S2; systolic thrill
• Echo: Valve area <1.0 cm² = severe; mean gradient >40 mmHg = severe
• Management: Symptomatic = surgical AVR or TAVI (Transcatheter Aortic Valve Implantation) - TAVI preferred for high-surgical-risk patients

Aortic Regurgitation (AR)

• Causes: RHD, bicuspid aortic valve, IE, aortic root dilation (Marfan syndrome, syphilitic aortitis, hypertension), ankylosing spondylitis
• Pathophysiology: Regurgitant volume into LV → ↑ LVEDV + LVESV → eccentric hypertrophy; wide pulse pressure (high SBP + low DBP = "water hammer" pulse)
• Exam: Early diastolic decrescendo murmur at right sternal border; wide pulse pressure; "pistol shot" femorals; de Musset's sign (head bobbing); Quincke's pulsations; Austin Flint murmur (functional MS from regurgitant jet)
• Management: Vasodilators (ACEi, nifedipine) for chronic symptomatic or LVEF reduction; AVR when symptomatic or LVEF <50% or LVESD >50 mm

Tricuspid / Pulmonary Valve Disease

• Tricuspid regurgitation: Most common secondary (from RHF, IE in IV drug users); management addresses underlying cause
• Pulmonary stenosis: Often congenital; balloon valvuloplasty if severe

Diagnostic Approach to Valvular Disease

Pharmacology

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5. CARDIAC FAILURE (HEART FAILURE)

Definition

Classification

By Ejection Fraction (EF)

By Side Affected

• Left heart failure: Pulmonary congestion; dyspnea, orthopnea, PND, pulmonary edema
• Right heart failure: Systemic venous congestion; raised JVP, peripheral edema, hepatomegaly
• Biventricular failure: Combined features; most common presentation

By Onset

• Acute: Sudden decompensation; pulmonary edema
• Chronic: Progressive; stable symptoms with exacerbations

NYHA Classification

Causes

• Ischemic heart disease (most common in developed countries; ~65%)
• Hypertension (chronic pressure overload → LVH → HFpEF; or acute → decompensation)
• Cardiomyopathy (dilated, hypertrophic, peripartum)
• Valvular heart disease (AS, MR, AR)

• Arrhythmias (rapid AF, tachycardia-mediated cardiomyopathy)
• Thyroid disease (hypo/hyperthyroidism)
• Anemia (high-output failure)
• Alcohol, drugs (anthracyclines, trastuzumab, cocaine)
• Infections (viral myocarditis, Chagas disease)
• Infiltrative disease (amyloidosis, sarcoidosis, hemochromatosis)
• Genetic/familial cardiomyopathies (mutations in cytoskeletal/nuclear proteins; autosomal dominant)
• Congenital heart disease

Pathophysiology

Neurohormonal Activation (Core Mechanism)

1. Sympathetic nervous system: ↑ norepinephrine → ↑ HR, ↑ contractility (short-term beneficial); chronic → receptor downregulation, cardiotoxicity, arrhythmias
2. RAAS: ↓ renal perfusion → ↑ renin → ↑ Ang II → vasoconstriction + aldosterone → Na⁺ and water retention → ↑ preload/afterload → worsens overload
3. ADH/Vasopressin: ↑ water retention → hyponatremia; vasoconstriction
4. Natriuretic peptides (BNP, ANP): Compensatory; ↑ natriuresis, vasodilation, inhibit RAAS; become overwhelmed

Ventricular Remodeling

HFpEF Pathophysiology

Clinical Manifestations

• Dyspnea on exertion, orthopnea, PND, bendopnea
• Basal crackles (pulmonary edema), pleural effusion (right-sided > left)
• S3 gallop (volume overload), S4 (stiff ventricle)
• Displaced apex (cardiomegaly)

• Elevated JVP (>3 cm above sternal angle + 5 = >8 cm H₂O)
• Pitting peripheral edema (bilateral), ascites
• Hepatomegaly (tender), hepatojugular reflux
• Pulsatile liver (TR), jaundice (hepatic congestion)

• Fatigue, exercise intolerance (>90% of patients)
• Cardiac cachexia (advanced HF; poor prognosis)
• Atrial fibrillation (~30%)
• Pulsus alternans (advanced HF; alternating pulse volume)
• Cognitive dysfunction

Diagnostic Approach

Management and Pharmacology

HFrEF (Evidence-Based "Quadruple Therapy")

• Loop diuretics: Furosemide 40-80 mg OD/BD (IV in acute decompensation); torsemide, bumetanide
• Thiazides: Metolazone (combined with furosemide for diuretic resistance)
• Spironolactone: Dual role (MRA + K-sparing diuretic)

• Hydralazine + Isosorbide dinitrate: For ACEi/ARB-intolerant patients; particularly beneficial in Black patients
• Digoxin: ↑ contractility (Na/K-ATPase inhibitor), rate control in AF; reduces hospitalizations but no mortality benefit; narrow TI
• Ivabradine: ↓ HR via HCN channel block; for sinus rhythm + HR >70 despite maximized beta-blocker
• Vericiguat: Soluble guanylate cyclase stimulator; high-risk HFrEF; ↑ cGMP → vasodilation + anti-remodeling

HFpEF

• Diuretics for congestion
• Control underlying hypertension aggressively
• Rate control for AF
• SGLT2 inhibitors (empagliflozin, dapagliflozin): Recently shown to reduce hospitalizations in HFpEF (EMPEROR-Preserved, DELIVER trials)
• Treat underlying cause (revascularization for ischemia, thyroid treatment)

Acute Decompensated Heart Failure

• IV loop diuretics: Furosemide 40-200 mg IV; adjust to clinical response
• Vasodilators: IV nitroglycerin (preload reduction), nitroprusside (preload + afterload); for hypertensive acute HF
• Inotropes (cardiogenic shock): Dobutamine (β1 agonist), milrinone (PDE3 inhibitor); bridge to device/transplant
• Non-invasive ventilation (CPAP/BiPAP): For acute pulmonary edema
• Vasopressors: Norepinephrine for cardiogenic shock with hypotension

Devices and Surgical

• ICD (Implantable Cardioverter Defibrillator): EF ≤35% on optimal medical therapy ≥3 months; reduce SCD
• CRT (Cardiac Resynchronization Therapy): EF ≤35% + LBBB + QRS ≥150 ms; improves symptoms and mortality
• LVAD (Left Ventricular Assist Device): Bridge to transplant or destination therapy
• Cardiac transplantation: End-stage HF; EF <25%; refractory to maximal therapy

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6. CARDIOMYOPATHY

Definition

Types

A. Dilated Cardiomyopathy (DCM)

• Most common type (~60% of cardiomyopathies)
• Definition: Ventricular dilation + systolic dysfunction (↓ EF) without known cause
• Causes: Idiopathic (most common), genetic (mutations in titin TTN, lamin LMNA, dystrophin DMD), alcohol, viral myocarditis (Coxsackie B, adenovirus, HIV), peripartum, anthracyclines (doxorubicin), trastuzumab, cocaine, selenium deficiency, thyroid disease, tachycardia-mediated
• Gross pathology: Dilated, flabby, globular heart; all 4 chambers enlarged; mural thrombi common
• Features: Systolic HF symptoms (dyspnea, fatigue, edema); LBBB; regurgitant murmurs (MR, TR); embolic events
• Management: Standard HFrEF quadruple therapy (ARNI/ACEi/ARB, beta-blocker, MRA, SGLT2i); anticoagulation if EF <35% + AF/thrombus; ICD/CRT; transplant for end-stage

B. Hypertrophic Cardiomyopathy (HCM)

• Definition: LV hypertrophy (usually asymmetric septal hypertrophy) without identifiable cause
• Genetics: Autosomal dominant; mutations in sarcomere proteins (β-myosin heavy chain MYH7, myosin binding protein C MYBPC3 - most common); familial in 40-60%
• Pathophysiology:
  • Systolic anterior motion (SAM) of mitral valve → dynamic LVOT obstruction (in ~25%) → HCM with obstruction (HOCM)
  • LV hypertrophy → diastolic dysfunction → ↑ filling pressures
  • Myocyte disarray + fibrosis → arrhythmic substrate → sudden cardiac death
• Features: Most commonly asymptomatic; exertional dyspnea, angina, syncope (especially with Valsalva/exertion); sudden cardiac death (most common cause of SCD in young athletes); harsh systolic murmur at LLSB that increases with Valsalva/standing and decreases with squatting/passive leg raise
• Diagnosis: Echo = LV wall thickness ≥15 mm (or ≥13 mm with family history); cardiac MRI; genetic testing
• Management:
  • Avoid dehydration, vasodilators, diuretics, digoxin, nitrates (worsen obstruction)
  • Beta-blockers (first-line): ↓ HR → ↑ diastolic filling time → ↓ obstruction
  • Disopyramide: Negative inotrope, reduces SAM/obstruction; combined with beta-blocker
  • Verapamil/diltiazem: For beta-blocker intolerant
  • Mavacamten (novel myosin inhibitor): FDA-approved for symptomatic obstructive HCM; reduces LVOT gradient
  • Septal reduction: Surgical myectomy (gold standard) or alcohol septal ablation (catheter-based)
  • ICD: SCD prevention for high-risk patients (prior arrest, family history of SCD, severe hypertrophy ≥30 mm, unexplained syncope, LVOT gradient ≥50, NSVT)

C. Restrictive Cardiomyopathy (RCM)

• Definition: Normal/near-normal LV size + function (EF preserved) but severely impaired filling (rigid walls) → ↑ filling pressures; resembles constrictive pericarditis
• Causes: Amyloidosis (most common; cardiac amyloid → thickened, sparkling walls on echo; ↓ voltage on ECG despite LVH), sarcoidosis, hemochromatosis, Fabry disease, glycogen storage diseases, eosinophilic endomyocardial disease (Loeffler), radiation-induced fibrosis
• Features: Dyspnea, fatigue, RHF signs (edema, ascites); normal or small LV; biatrial enlargement; normal or near-normal EF
• Diagnosis: Echo (biatrial enlargement, diastolic dysfunction, preserved EF); cardiac MRI (late gadolinium enhancement characterizes infiltrative patterns); biomarkers (BNP, troponin); biopsy if diagnosis unclear
• Management: Largely supportive; diuretics (cautiously); treat underlying cause; transthyretin amyloidosis: tafamidis (TTR stabilizer) - reduces mortality in ATTR amyloidosis (ATTR-ACT trial); patisiran (siRNA) or inotersen (antisense oligonucleotide) for hATTR; transplant for end-stage

D. Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)

• Replacement of RV myocardium with fibrofatty tissue → RV dilation + dysfunction + arrhythmias
• Genetics: Desmosome mutations (plakophilin-2 PKP2, desmoglein, desmocollin)
• SCD risk in young athletes; epsilon wave on ECG; "stack of coins" sign on imaging; cardiac MRI diagnostic
• ICD + beta-blockers; avoid competitive sports

E. Other Cardiomyopathies

• Peripartum cardiomyopathy (PPCM): Develops in last month of pregnancy to 5 months postpartum; EF <45%; bromocriptine may accelerate recovery (blocks prolactin); high chance of recovery
• Stress cardiomyopathy (Takotsubo): Transient LV apical ballooning after emotional/physical stress; catecholamine surge; post-menopausal women; full recovery usual
• Tachycardia-induced cardiomyopathy: Reversible with rate control

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7. PERICARDITIS

Definition

1. Characteristic chest pain (sharp, pleuritic, positional - worse supine, better sitting forward)
2. Pericardial friction rub
3. Characteristic ECG changes
4. New/worsening pericardial effusion

Types

• Acute pericarditis: <4-6 weeks
• Incessant pericarditis: >4-6 weeks but <3 months
• Recurrent pericarditis: Documented recurrence after symptom-free interval ≥4-6 weeks
• Chronic pericarditis: >3 months
• Pericardial effusion: Fluid accumulation in pericardial space
• Cardiac tamponade: Life-threatening compression of heart from pericardial effusion
• Constrictive pericarditis: Fibrotic/calcified pericardium → impaired cardiac filling

Causes

Pathophysiology

• Intrapericardial pressure rises above intracardiac pressure
• Cardiac chambers compressed → ↓ ventricular filling → ↓ cardiac output → tamponade

Diagnostic Approach

Management and Pharmacology

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8. INFECTIVE ENDOCARDITIS (IE)

Definition

Types

By Clinical Course

• Acute IE: Rapid, fulminant course over days-weeks; S. aureus most common; previously normal valves can be affected
• Subacute IE (SBE): Indolent course over weeks-months; viridans streptococci most common; typically on previously damaged valves

By Valve Type

• Native valve endocarditis (NVE): Affects native heart valves
• Prosthetic valve endocarditis (PVE): Early (<60 days of surgery) - S. epidermidis, S. aureus; Late (>60 days) - similar to NVE
• IVDU-associated IE: Right-sided; tricuspid valve most common; S. aureus dominant; septic pulmonary emboli

Causes / Organisms

Pathophysiology

1. Bacteremia (from dental/GI/GU procedures, IV drug use, intravascular devices, skin infections) → bacteria seed damaged endothelium or normal endothelium (S. aureus)
2. Endothelial injury (from turbulent flow in valvular disease, congenital defects) → fibrin-platelet thrombus formation (non-bacterial thrombotic endocarditis - NBTE) → colonization by bacteria during bacteremia
3. Vegetation formation: Bacteria + fibrin + platelets accumulate → friable vegetations → progressive valve destruction
4. Consequences:
   • Local: Valve perforation, rupture, abscess formation, fistulae, conduction abnormalities (AV block from septal abscess)
   • Embolic: Systemic emboli (stroke, renal/splenic infarcts, Janeway lesions) from left-sided IE; pulmonary emboli from right-sided IE
   • Immunologic: Osler's nodes, Roth spots, glomerulonephritis (immune complex deposition)

Diagnostic Approach (Duke Criteria)

1. Positive blood cultures: Typical organism in 2 separate cultures (S. viridans, S. bovis, HACEK, S. aureus, Enterococcus without primary focus); OR persistently positive cultures ≥12 hours apart; OR single positive culture for Coxiella
2. Evidence of endocardial involvement: Positive echocardiography (vegetation, abscess, new valvular regurgitation) OR positive 18F-FDG PET/CT

1. Predisposing heart condition or IVDU
2. Fever >38°C
3. Vascular phenomena: Arterial emboli, septic pulmonary infarcts, Janeway lesions, intracranial hemorrhage, conjunctival hemorrhage
4. Immunologic phenomena: Glomerulonephritis, Osler's nodes, Roth spots, positive rheumatoid factor
5. Microbiological evidence: Positive blood culture not meeting major criteria

Management and Pharmacology

Antibiotic Therapy (Empirical, then targeted)

• Native valve: Ampicillin + flucloxacillin + gentamicin (covers streptococci, staph, enterococci)
• Penicillin allergy: Vancomycin + gentamicin
• PVE/healthcare-associated: Vancomycin + gentamicin ± rifampicin

Surgical Indications for IE

• Urgent (emergency): Acute severe aortic or mitral regurgitation with hemodynamic instability; perivalvular abscess with fistula/septic pericarditis; uncontrolled infection
• Urgent (within days): Persisting bacteremia/fever >7-10 days despite appropriate antibiotics; large mobile vegetation with embolic events; S. aureus PVE
• Elective: PVE with significant valve dysfunction after completing antibiotics

IE Prophylaxis

• Prosthetic heart valves
• Previous IE
• Unrepaired cyanotic CHD
• Repaired CHD with prosthetic material (first 6 months)
• Cardiac transplant recipients with valvulopathy

• Amoxicillin 2g oral 30-60 min before procedure
• Clindamycin 600mg oral (if penicillin allergy)
• Ampicillin 2g IV/IM (if unable to take orally)

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9. HYPERTENSION (HTN)

Definition

Classification

Causes

Primary/Essential Hypertension

• Genetic predisposition + environmental factors
• High sodium intake, obesity (↑ RAAS + sympathetic activation), sedentary lifestyle, alcohol, stress
• Pathophysiology: ↑ CO + ↑ SVR; complex interplay of RAAS, SNS, endothelial dysfunction, renal Na+ handling

Secondary Hypertension

Pathophysiology

Primary HTN

• Increased cardiac output: Sympathetic overactivity (↑ HR, ↑ contractility) + volume expansion (↑ Na retention)
• Increased peripheral vascular resistance: Endothelial dysfunction → ↓ NO → vasoconstriction; RAAS activation → Ang II → vasoconstriction + aldosterone → Na retention; structural vascular remodeling (smooth muscle hypertrophy of arterioles)
• RAAS overactivation: Key pathogenic pathway; Ang II causes vasoconstriction, Na retention, aldosterone release, cardiac and vascular remodeling
• Renal pressure-natriuresis curve: Shift to the right in essential HTN - kidney requires higher BP to excrete normal Na load

Target Organ Damage

Diagnostic Approach

Management

Non-Pharmacological (All stages)

• Weight loss: Each 1 kg → ~1 mmHg ↓ SBP
• DASH diet (Dietary Approaches to Stop Hypertension): Rich in fruits, vegetables, low-fat dairy, limited sodium → ↓ SBP 8-14 mmHg
• Sodium restriction: <2 g/day → ↓ SBP 2-8 mmHg
• Physical activity: ≥150 min/week moderate aerobic exercise → ↓ SBP 4-9 mmHg
• Alcohol reduction: ≤2 drinks/day men, ≤1 women → ↓ SBP 2-4 mmHg
• Smoking cessation: Reduces overall CV risk (not directly BP)

Pharmacological Treatment

• General: <130/80 mmHg (ACC/AHA); <140/90 mmHg (ESC/NICE)
• CKD + proteinuria: <130/80 mmHg
• Diabetes: <130/80 mmHg
• Elderly (>65-80 yr): <130/80 mmHg if tolerated; avoid symptomatic hypotension

First-Line Drug Classes

Second/Third-Line Agents

Special Situations

Resistant Hypertension

• Non-adherence (most common)
• White coat effect → ABPM
• Secondary causes (especially primary aldosteronism)
• Interfering medications (NSAIDs, OCP, decongestants)

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• Robbins, Cotran & Kumar - Pathologic Basis of Disease (pp. 496-530)
• Goldman-Cecil Medicine, International Edition (Chapters 45, 64, 114)
• Tintinalli's Emergency Medicine (pp. 862-870, 3183-3192)
• Textbook of Family Medicine, 9th Edition (p. 698)
• Fuster and Hurst's The Heart, 15th Edition
• Robbins & Kumar Basic Pathology (pp. 363, 659)
• Lippincott Illustrated Reviews: Pharmacology
• Braunwald's Heart Disease, 2-Volume Set