🫁 RESPIRATORY SYSTEM — High-Yield MCQ Points

Pneumonia

• CAP (Community-Acquired Pneumonia): Most common organism = Streptococcus pneumoniae. Atypical coverage (Legionella, Mycoplasma, Chlamydia) required → use fluoroquinolone or β-lactam + macrolide
• CURB-65 Score: Confusion, Urea >7 mmol/L, RR ≥30, BP <90/60, Age ≥65 — score ≥2 = hospitalize; ≥3 = ICU consider
• Legionella: Pontiac fever vs Legionnaires' disease; urine antigen test is best rapid test; treat with fluoroquinolone or azithromycin
• VAP (Ventilator-Associated Pneumonia): No single diagnostic criterion is reliable; diagnosis requires ≥48h on mechanical ventilation + new infiltrate + purulent secretions ± fever
• Aspiration Pneumonia: Right lower lobe (upright), right upper lobe posterior segment (supine); anaerobic coverage required

COPD

• Diagnosis: FEV₁/FVC <0.70 post-bronchodilator (spirometry required — NOT clinical alone)
• GOLD Staging: GOLD 1 = FEV₁ ≥80%; GOLD 2 = 50–79%; GOLD 3 = 30–49%; GOLD 4 = <30%
• Exacerbation treatment: SABA + systemic steroids + antibiotics (if purulent sputum); antibiotics of choice = azithromycin, amoxicillin-clavulanate, doxycycline
• Chronic management: LABA + LAMA > LABA alone; add ICS if FEV₁ <60% or frequent exacerbations
• Only interventions that reduce mortality in COPD: Smoking cessation + Long-term O₂ therapy (PaO₂ ≤55 mmHg or SaO₂ ≤88%)

Asthma

• Diagnosis: Reversible airflow obstruction (FEV₁ improves ≥12% and ≥200 mL after bronchodilator)
• Step-up therapy: Step 1 = SABA PRN → Step 2 = Low-dose ICS → Step 3 = Low-dose ICS + LABA → Step 4 = Medium-dose ICS + LABA → Step 5 = add tiotropium or biologic
• Status asthmaticus: IV magnesium sulfate if not responding to standard bronchodilators
• Biologics: Omalizumab (anti-IgE) for severe allergic asthma; Mepolizumab (anti-IL-5) for eosinophilic asthma

Interstitial Lung Disease

• Smoking-related ILD: Respiratory bronchiolitis-ILD (RB-ILD) and DIP → smoking cessation is cornerstone of treatment; steroids may help
• IPF (Idiopathic Pulmonary Fibrosis): Progressive, no reversibility; CT = UIP pattern (honeycombing + traction bronchiectasis); treat with pirfenidone or nintedanib
• Hypersensitivity Pneumonitis: Exposure history key; remove antigen; acute = steroids
• Sarcoidosis: Bilateral hilar lymphadenopathy on CXR; elevated ACE levels; treat with steroids if symptomatic

Pulmonary Embolism

• Wells Score: ≥5 = high probability → CT pulmonary angiography (CTPA) is gold standard
• Treatment: LMWH/UFH → transition to warfarin or DOACs (rivaroxaban, apixaban); thrombolytics for massive PE with hemodynamic instability
• Massive PE signs: Hypotension, RV strain on Echo/ECG (S1Q3T3 pattern, new RBBB), elevated troponin

Lung Cancer

• Screening: Low-dose CT annually in adults 50–80 years with ≥20 pack-year history, currently smoke or quit within 15 years
• Small Cell Lung Cancer (SCLC): Central, associated with paraneoplastic syndromes (SIADH, ACTH → Cushing's, Eaton-Lambert); limited stage = chemo + radiation; extensive = chemo alone
• Non-Small Cell (NSCLC): Adenocarcinoma = most common, peripheral; Squamous cell = central, hypercalcemia (PTHrP); Large cell = peripheral, gynecomastia
• Pancoast tumor: Apex lung cancer → Horner syndrome (ptosis, miosis, anhidrosis) + shoulder/arm pain (C8, T1, T2)

🫘 RENAL SYSTEM — High-Yield MCQ Points

Acute Kidney Injury (AKI)

• KDIGO Criteria: Rise in Cr ≥0.3 mg/dL within 48h OR ≥1.5× baseline within 7 days OR urine output <0.5 mL/kg/h for ≥6h
• Pre-renal AKI: FeNa <1%, BUN/Cr ratio >20:1, concentrated urine (high specific gravity, osmolality >500)
• Intrinsic AKI / ATN: FeNa >2%, granular "muddy brown" casts in urine, BUN/Cr ratio ~10:1
• Emergent dialysis indications (AEIOU): Acidosis (metabolic, refractory), Electrolyte imbalance (hyperkalemia), Ingestion/toxin, Overload (fluid), Uremia symptoms (encephalopathy, pericarditis, bleeding)
• Contrast nephropathy prevention: Pre-hydration with isotonic saline; avoid concurrent NSAIDs/diuretics

Chronic Kidney Disease (CKD)

• Staging: Stage 1 = GFR ≥90 (with markers); Stage 3a = 45–59; Stage 3b = 30–44; Stage 4 = 15–29; Stage 5 = <15 (dialysis)
• Complications: Anemia (↓EPO → normocytic), renal osteodystrophy (↑PTH, ↓vit D, ↑phosphate), metabolic acidosis, hyperkalemia, hypertension
• Management: ACE inhibitors/ARBs = first-line to reduce proteinuria and slow progression; treat anemia with EPO + iron; phosphate binders
• Proteinuria: >3.5 g/day = nephrotic range; <3.5 g/day = nephritic

Glomerulonephritis

Nephrotic Syndrome

• Classic triad: Proteinuria >3.5 g/day + hypoalbuminemia + edema
• Additional findings: Hyperlipidemia, lipiduria (oval fat bodies, "Maltese cross" birefringence), hypercoagulability (↑renal vein thrombosis risk)
• Renal vein thrombosis: Complication of nephrotic syndrome (especially membranous), presents with flank pain + hematuria

Electrolytes

• Hyponatremia: SIADH = urine Na >40, urine osmolality >100; treat with fluid restriction; if severe (Na <120 with symptoms) → 3% hypertonic saline (correct at max 8 mEq/L/24h to avoid osmotic demyelination)
• Hyperkalemia ECG changes: Peaked T waves → widened QRS → sine wave → VF; treat with calcium gluconate (stabilize membrane), insulin + glucose (shift K+), Kayexalate/patiromer (eliminate)
• Hypermagnesemia: Deep tendon reflexes lost first; respiratory arrest occurs; treat with IV calcium gluconate

❤️ CARDIOVASCULAR SYSTEM — High-Yield MCQ Points

Heart Failure

• HFrEF (EF <40%): Mortality-reducing drugs = ACE inhibitor/ARB (or ARNI = sacubitril/valsartan), beta-blocker (carvedilol, metoprolol succinate, bisoprolol), aldosterone antagonist (spironolactone), SGLT2 inhibitor (dapagliflozin)
• HFpEF (EF ≥50%): No proven mortality-reducing drug except SGLT2 inhibitors; control rate, BP, and volume
• BNP: <100 pg/mL excludes HF; >400 pg/mL confirms HF; elevated in RV strain, PE, and renal failure too
• NYHA Classification: I = no symptoms; II = symptoms with moderate activity; III = symptoms with minimal activity; IV = symptoms at rest

Acute MI

• STEMI management: PCI within 90 min (door-to-balloon) or fibrinolysis within 30 min (door-to-needle) if no PCI available within 120 min
• NSTEMI/UA: Antiplatelet (aspirin + P2Y12 inhibitor) + anticoagulation; early invasive strategy if high-risk (TIMI ≥3 or GRACE score)
• Complications: Papillary muscle rupture (acute MR, 3–5 days), free wall rupture (tamponade, 3–5 days), VSD (days 3–7), Dressler syndrome (pericarditis 2–10 weeks post-MI), LV aneurysm (weeks–months)
• Killip Classification: I = no HF; II = mild HF (S3, crackles <50% lung); III = pulmonary edema; IV = cardiogenic shock

Arrhythmias

• AFib management: Rate control (beta-blockers, CCBs) vs rhythm control (cardioversion, antiarrhythmics); anticoagulate if CHA₂DS₂-VASc ≥2 (men) / ≥3 (women)
• CHA₂DS₂-VASc scoring: CHF=1, HTN=1, Age ≥75=2, DM=1, Stroke/TIA=2, Vascular disease=1, Age 65–74=1, Sex female=1
• WPW Syndrome: Delta wave + short PR; avoid AV nodal blockers (adenosine, digoxin, CCBs) in AFib with WPW → can precipitate VF; use procainamide
• Torsades de Pointes: Prolonged QT + polymorphic VT; causes = hypokalemia, hypomagnesemia, class IA/III antiarrhythmics, certain antibiotics; treat with IV magnesium

Valvular Heart Disease

Hypertension

• Hypertensive emergency: BP >180/120 with end-organ damage; lower MAP by max 25% in first hour; use IV labetalol, nicardipine, or nitroprusside
• Hypertensive urgency: Severe BP without end-organ damage; oral agents OK; lower over 24–48h
• 1st-line by comorbidity: DM/CKD with proteinuria = ACEi/ARB; post-MI = beta-blocker + ACEi; HF = ACEi + beta-blocker + diuretic; Pregnancy = methyldopa, hydralazine, nifedipine (NOT ACEi/ARBs)

🦋 ENDOCRINE SYSTEM — High-Yield MCQ Points

Diabetes Mellitus

• Diagnosis criteria (any one):
  • Fasting glucose ≥126 mg/dL (×2)
  • 2-hour glucose ≥200 mg/dL (OGTT)
  • Random glucose ≥200 mg/dL + symptoms
  • HbA1c ≥6.5%
• Pre-diabetes: Fasting 100–125, OGTT 140–199, HbA1c 5.7–6.4%
• DKA vs HHS:
  • DKA: pH <7.3, glucose >250, ketonemia/ketonuria, anion gap metabolic acidosis; mainly T1DM
  • HHS: pH >7.3, glucose >600, no significant ketones, serum osmolality >320; mainly T2DM
• DKA treatment: IV fluids first, then insulin; replace K+ if K <3.5 before starting insulin; switch to SC insulin when pH >7.3, AG normal, patient eating
• T2DM 1st-line: Metformin (reduces hepatic gluconeogenesis); avoid in GFR <30; SGLT2 inhibitors for HF/CKD; GLP-1 agonists for weight loss/CV benefit
• Diabetic complications: Nephropathy (microalbuminuria first sign), retinopathy (most common cause of blindness in working-age adults), peripheral neuropathy (stocking-glove), autonomic neuropathy (gastroparesis, orthostatic hypotension)

Thyroid Disease

• Hypothyroidism: ↑TSH + ↓free T4; most common cause = Hashimoto's (autoimmune, anti-TPO antibodies); treat with levothyroxine; monitor TSH 6–8 weeks after dose change
• Hyperthyroidism: ↓TSH + ↑free T4/T3; most common cause = Graves' disease (TSI antibodies, exophthalmos, pretibial myxedema); treat with methimazole, radioactive iodine, or surgery
• Thyroid storm: Life-threatening hyperthyroidism; treat with propranolol (blocks T4→T3 conversion + symptoms) + PTU (not methimazole in acute) + iodine (1 hour after PTU) + steroids + cooling
• Thyroid nodule workup: Check TSH → if low, radionuclide scan; if normal/high, ultrasound → FNA for suspicious nodules ≥1 cm
• Thyroid cancer: Papillary = most common (psammoma bodies, "Orphan Annie" nuclei), best prognosis; Medullary = calcitonin-producing, associated with MEN2; Anaplastic = worst prognosis

Adrenal Disease

• Cushing's syndrome: ↑cortisol, central obesity, striae, moon face, buffalo hump, HTN, hyperglycemia, osteoporosis; most common cause = exogenous steroids; endogenous = pituitary adenoma (Cushing's disease)
• Workup: 24h urine free cortisol OR late-night salivary cortisol → 1 mg overnight dexamethasone suppression test (fails to suppress = Cushing's) → CRH stimulation to distinguish pituitary vs ectopic
• Addison's disease: ↓cortisol + ↓aldosterone; hyperpigmentation (↑ACTH), hyperkalemia, hyponatremia, hypoglycemia; stimulation test: cosyntropin → flat cortisol response
• Adrenal crisis: Hypotension, shock → hydrocortisone 100 mg IV STAT
• Pheochromocytoma: Episodic HTN, headache, diaphoresis, palpitations; 10% rule (bilateral, malignant, extra-adrenal, familial, in children); diagnose with plasma/urine metanephrines; alpha-block first (phenoxybenzamine), then beta-block before surgery

Parathyroid / Calcium

• Primary Hyperparathyroidism: ↑Ca²⁺, ↓PO₄³⁻, ↑PTH; most common cause = single parathyroid adenoma; "bones, stones, groans, psychic moans"
• Hypercalcemia treatment: IV fluids → furosemide → bisphosphonates (zoledronic acid) → calcitonin for rapid effect → steroids (if sarcoid/lymphoma)
• Hypoparathyroidism: ↓Ca²⁺, ↑PO₄³⁻, ↓PTH; most common cause = post-surgical; Chvostek's sign (facial nerve tap), Trousseau's sign (carpal spasm with BP cuff)
• Pseudohypoparathyroidism: ↓Ca²⁺, ↑PTH (target organ resistance); short stature, short 4th metacarpal (Albright hereditary osteodystrophy)

MEN Syndromes

🦴 MUSCULOSKELETAL SYSTEM — High-Yield MCQ Points

Rheumatoid Arthritis (RA)

• Diagnosis: ≥4 of 7 ACR criteria OR 2010 ACR/EULAR criteria (joints + serology + duration + acute phase reactants)
• Classic findings: Symmetric, small joint polyarthritis (MCP, PIP — NOT DIP); morning stiffness >1 hour; RF and anti-CCP positive; pannus formation → cartilage destruction
• Extra-articular: Rheumatoid nodules, pulmonary fibrosis, Felty's syndrome (RA + splenomegaly + neutropenia), Caplan syndrome (RA + pneumoconiosis), pericarditis, Sjögren's overlap
• Treatment: Methotrexate = cornerstone DMARD; add hydroxychloroquine and/or sulfasalazine; biologics (anti-TNF: etanercept, infliximab) if MTX fails; screen for TB before anti-TNF therapy
• Contraindication: MTX is teratogenic — contraceptive counseling mandatory

Osteoarthritis (OA)

• Features: DIP (Heberden's nodes) and PIP (Bouchard's nodes) — NOT MCP; asymmetric; no systemic symptoms; morning stiffness <30 min; X-ray = joint space narrowing + osteophytes + subchondral sclerosis
• Treatment: Acetaminophen first-line, then NSAIDs; intra-articular corticosteroids or hyaluronic acid; joint replacement for severe

Gout

• Pathophysiology: Hyperuricemia → monosodium urate crystal deposition; negatively birefringent, needle-shaped crystals (yellow parallel, blue perpendicular to polarizer)
• Attacks: 1st MTP joint (podagra) most common; triggered by dehydration, alcohol, thiazide diuretics, surgery/illness
• Acute treatment: NSAIDs (indomethacin) OR colchicine OR corticosteroids — do NOT start allopurinol during acute attack (can prolong it)
• Chronic tophaceous gout: Urate lowering therapy = allopurinol (xanthine oxidase inhibitor) or febuxostat; target uric acid <6 mg/dL; colchicine prophylaxis when starting ULT
• Drug-related hyperuricemia: Thiazides, loop diuretics, aspirin (low-dose), cyclosporine, pyrazinamide

Pseudogout (CPPD)

• Crystals: Calcium pyrophosphate — positively birefringent, rhomboid-shaped (blue parallel to polarizer)
• Location: Wrist, knee most common; chondrocalcinosis on X-ray (calcification of articular cartilage)
• Treatment: Same as acute gout (NSAIDs, colchicine, steroids) — no specific ULT

SLE (Systemic Lupus Erythematosus)

• SLICC/ACR Criteria: Mnemonic — "SOAP BRAIN MD"
  • Serositis, Oral ulcers, Arthritis, Photosensitivity, Blood disorders (hemolytic anemia/leukopenia/thrombocytopenia), Renal (proteinuria/casts), ANA, Immunologic (anti-dsDNA/anti-Sm/anti-phospholipid), Neurologic (seizure/psychosis), Malar rash, Discoid rash
• Antibodies: ANA = screening (sensitive, not specific); Anti-dsDNA + Anti-Sm = specific; Anti-Sm = specific to SLE; Anti-histone = Drug-induced lupus; Anti-Ro/SS-A = neonatal lupus + Sjögren's; Anti-phospholipid = clotting + recurrent miscarriages
• Lupus nephritis: Class III/IV (proliferative) = most serious → treat with IV methylprednisolone + cyclophosphamide or mycophenolate
• Drug-induced lupus: Hydralazine, procainamide, isoniazid, minocycline; anti-histone antibodies; resolves with drug discontinuation

Spondyloarthropathies

• Ankylosing Spondylitis: HLA-B27 positive; sacroiliitis + bamboo spine; young men; anterior uveitis; treatment = NSAIDs 1st-line, then anti-TNF
• Reactive Arthritis (formerly Reiter's): "Can't see, can't pee, can't climb a tree"; after GI (Salmonella, Shigella, Campylobacter, Yersinia) or urogenital infection (Chlamydia); sterile joint
• Psoriatic Arthritis: Asymmetric oligoarthritis; DIP involvement; "sausage digit" (dactylitis); nail pitting; skin psoriasis usually precedes joint disease

Osteoporosis

• Diagnosis: DEXA scan; T-score ≤ −2.5 = osteoporosis; −1 to −2.5 = osteopenia
• Screening: Women ≥65; postmenopausal women <65 with risk factors
• Treatment: Calcium + vitamin D + weight-bearing exercise; bisphosphonates 1st-line (alendronate, risedronate); denosumab or teriparatide for severe cases
• Bisphosphonate complications: Osteonecrosis of jaw, atypical femoral fractures, esophagitis (take upright with water)

🔵 GASTROINTESTINAL SYSTEM — High-Yield MCQ Points

Esophagus / GERD

• GERD: Burning epigastric/chest pain; worse after eating, lying down; treat with lifestyle changes → H2 blockers → PPIs (most effective)
• Barrett's esophagus: Metaplasia of squamous → columnar (intestinal) epithelium; risk factor for esophageal adenocarcinoma; surveillance endoscopy required
• Achalasia: Failure of LES relaxation; barium swallow = "bird-beak" appearance; manometry = gold standard (aperistalsis + elevated LES tone); treat with pneumatic dilation or Heller myotomy
• Esophageal cancer: Adenocarcinoma = distal, associated with GERD/Barrett's; Squamous cell = proximal/middle, associated with alcohol, smoking, achalasia, caustic stricture

Peptic Ulcer Disease

• H. pylori: Most common cause of peptic ulcers; diagnose with urea breath test (best for active infection), stool antigen test, or endoscopic biopsy (gold standard); triple therapy = PPI + clarithromycin + amoxicillin ×14 days (or metronidazole if penicillin-allergic)
• Duodenal ulcer: Relieved by food; anterior wall = perforation → free air under diaphragm; posterior wall = erodes gastroduodenal artery → massive hemorrhage
• Gastric ulcer: Pain worse with eating; always biopsy to exclude malignancy; benign ulcers have smooth margins
• NSAID-induced ulcers: Avoid NSAIDs; if unavoidable, co-prescribe PPI or misoprostol
• Zollinger-Ellison Syndrome: Gastrinoma (duodenum/pancreas); recurrent/refractory peptic ulcers + diarrhea; ↑fasting gastrin; secretin stimulation test = paradoxical rise in gastrin; associated with MEN1

Inflammatory Bowel Disease

• 5-ASA: First-line for mild-moderate UC; not effective in Crohn's
• Biologics: Anti-TNF (infliximab, adalimumab) for moderate-severe or steroid-dependent IBD
• Extra-intestinal manifestations: Erythema nodosum (parallels disease activity), pyoderma gangrenosum (does NOT parallel activity), primary sclerosing cholangitis (more common in UC), uveitis, ankylosing spondylitis

Liver Disease

• Hepatitis B serologies:
  • HBsAg = active infection; HBsAb = immunity (vaccination or recovery); HBcAb IgM = acute infection; HBcAb IgG = past infection; HBeAg = high infectivity
  • Window period: HBsAg negative, HBsAb negative, HBcAb IgM positive
• Hepatitis C: Most common cause of liver transplant in USA; treat with direct-acting antivirals (ledipasvir/sofosbuvir); >95% cure rate
• Cirrhosis complications: Portal hypertension → varices (band ligation, propranolol prophylaxis), ascites (spironolactone + furosemide), SBP (spontaneous bacterial peritonitis — PMN >250/mm³ in ascites fluid, treat with cefotaxime), hepatic encephalopathy (treat with lactulose + rifaximin), hepatorenal syndrome
• MELD score: Used for liver transplant priority; uses creatinine, bilirubin, INR
• Alcoholic hepatitis: AST:ALT ratio >2:1 (but both usually <300); treat with steroids (Maddrey DF ≥32 or MELD >20)
• NAFLD/NASH: Metabolic syndrome; steatosis → steatohepatitis → cirrhosis; no alcohol history; treat with lifestyle modification

Colorectal Cancer

• Screening: Average risk = colonoscopy at age 45, every 10 years; high risk (1st-degree relative <60, FAP, Lynch) = earlier and more frequent
• FAP (Familial Adenomatous Polyposis): APC gene mutation; hundreds of polyps; prophylactic colectomy; also consider CHRPE, desmoid tumors (Gardner's syndrome)
• Lynch Syndrome (HNPCC): MLH1/MSH2 mutations; mismatch repair genes; right-sided colon cancer + endometrial cancer risk; Amsterdam criteria
• CEA: Tumor marker for monitoring treatment response and recurrence — NOT diagnostic
• Duke's/TNM staging: Complete resection + lymph node involvement determines whether adjuvant chemotherapy (FOLFOX) is needed

Pancreatitis

• Acute pancreatitis most common causes: Gallstones (#1) and Alcohol (#2) — "GET SMASHED" mnemonic
• Ranson's criteria: ≥3 = severe disease; predicts mortality
• Management: IV fluids + NPO + analgesia; no routine antibiotics; ERCP if gallstone pancreatitis with cholangitis
• Chronic pancreatitis: Alcohol most common cause; pancreatic calcifications on X-ray; steatorrhea + weight loss; treat with pancreatic enzyme replacement + fat-soluble vitamins
• Pancreatic cancer: Head of pancreas = painless jaundice (Courvoisier sign = palpable non-tender gallbladder); CA 19-9 = tumor marker (not diagnostic); Trousseau syndrome = migratory thrombophlebitis

Sources: Harrison's Principles of Internal Medicine 22E, Goldman-Cecil Medicine, Fishman's Pulmonary Diseases, Comprehensive Clinical Nephrology 7E, Braunwald's Heart Disease, Fuster & Hurst's The Heart, Yamada's Textbook of Gastroenterology, Katzung's Pharmacology 16E, Goodman & Gilman's Pharmacological Basis of Therapeutics.---

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