Liver Disease: A Comprehensive Overview

1. Anatomy & Functional Overview

• Portal vein (~75%) - carries nutrient-rich blood from the gut
• Hepatic artery (~25%) - carries oxygenated blood

2. Classification of Liver Diseases

3. Viral Hepatitis

Hepatitis A (HAV)

• Fecal-oral transmission; self-limiting; no chronic form
• Vaccines available; supportive treatment

Hepatitis B (HBV)

• Bloodborne/sexual/vertical transmission
• Acute infection: 90-95% of adults clear spontaneously
• Chronic HBV: defined as HBsAg+ for >6 months; 5-10% of adults progress to chronic disease
• Major complication: cirrhosis and HCC
• Treatment: tenofovir, entecavir (nucleotide analogues)

Hepatitis C (HCV)

• Bloodborne transmission; most common cause of chronic liver disease
• ~75-85% of acute infections become chronic
• Can progress to cirrhosis over 20-30 years
• Curative with direct-acting antivirals (DAAs) - >95% SVR
• (Schwartz's Principles of Surgery, 11e)

Hepatitis D (HDV)

• Co-infection or superinfection with HBV only; worsens prognosis

Hepatitis E (HEV)

• Fecal-oral; self-limiting in immunocompetent; can be severe in pregnancy

4. Alcohol-Related Liver Disease (ALD)

1. Steatosis (fatty liver): reversible with abstinence; mild elevation in ALP and bilirubin
2. Alcoholic steatohepatitis (ASH): hepatocyte necrosis, Mallory bodies, neutrophilic infiltrate, perivenular inflammation
3. Cirrhosis: irreversible; 15-20 years of excess drinking typically required; steatohepatitis can occur after weeks-months of heavy use

• AST:ALT ratio >2:1 (distinguishing feature from other liver diseases)
• Transaminases rarely exceed 500 U/mL
• Hyperbilirubinemia, elevated ALP, neutrophilic leukocytosis

• Each bout of alcoholic hepatitis carries 10-20% risk of death
• With repeated bouts, cirrhosis develops in ~1/3 of patients within a few years
• 5-year survival ~90% with abstinence (free of jaundice/ascites/hematemesis) vs. 50-60% in those who continue drinking
• Causes of death: hepatic failure, massive GI hemorrhage, intercurrent infection, hepatorenal syndrome, HCC (3-6%)

5. Nonalcoholic Fatty Liver Disease (NAFLD) / MASLD

• Simple steatosis (NAFL): hepatic fat >5% without inflammation; largely benign
• NASH (nonalcoholic steatohepatitis): steatosis + hepatocyte injury + inflammation + fibrosis
• NASH cirrhosis + HCC risk

• NAFLD prevalence: ~25% globally
• NASH affects 3-5% of the population
• ~1 in 10 NASH patients progress to cirrhosis
• NASH is increasingly the leading cause of HCC (surpassing HCV in many populations)

6. Cirrhosis

Morphologic Classification

Epidemiology

• Causes 30,000 deaths/year in the United States
• 5-year mortality of ESLD: 50% (70% from liver failure itself)
• 40% of cirrhotic patients are asymptomatic at presentation

Prognosis (Symptom to Diagnosis, 4e)

• Median survival from diagnosis of compensated cirrhosis: 10-13 years
• Up to 60% progress to decompensated cirrhosis by 10 years
• After decompensation without transplant: 85% 5-year mortality

7. Complications of Cirrhosis / End-Stage Liver Disease (ESLD)

A. Portal Hypertension

1. Formation of portosystemic collaterals (varices)
2. Splanchnic vasodilation
3. Renal vasoconstriction - salt and water retention
4. Increased cardiac output
5. Decreased production of albumin and clotting factors
6. Edema (low oncotic pressure + increased hydrostatic pressure)

B. Variceal Bleeding

• Gastroesophageal varices form via the coronary (left gastric) vein
• HVPG >12 mmHg is threshold for variceal bleeding
• Management:
  • Acute: IV octreotide (splanchnic vasoconstriction) + endoscopic band ligation
  • Prevention: non-selective beta-blockers (propranolol, nadolol) or band ligation
  • Refractory: TIPS (transjugular intrahepatic portosystemic shunt) - controls bleeding in >90% of cases
  • TIPS complications: hepatic encephalopathy (25-30%), stent thrombosis, decreased hepatic function

C. Ascites

• Combination of portal hypertension + hypoalbuminemia + sodium retention
• Diagnosed by paracentesis; SAAG ≥1.1 g/dL indicates portal hypertension
• Treatment: sodium restriction, diuretics (spironolactone ± furosemide), large-volume paracentesis for refractory cases

D. Hepatic Encephalopathy (HE)

• Neuropsychiatric dysfunction from portosystemic shunting of ammonia and other toxins
• Grading scale (West Haven):
  • Grade 1: subtle change in consciousness
  • Grade 2: disoriented, inappropriate behavior
  • Grade 3: somnolent but arousable
  • Grade 4: comatose
• Treatment: lactulose (reduces ammonia), rifaximin (antibiotic to alter gut flora)

E. Hepatorenal Syndrome (HRS)

• Functional renal failure in advanced cirrhosis; diagnosis of exclusion
• Type 1 (acute): rapid GFR decline; often precipitated by SBP, hemorrhage; poor prognosis
• Type 2 (chronic): slower decline; associated with refractory ascites
• Treatment: terlipressin + albumin; bridge to liver transplant

F. Spontaneous Bacterial Peritonitis (SBP)

• Infection of ascitic fluid (PMNs >250/mm³); most common organism: E. coli
• Prophylaxis: norfloxacin in high-risk patients
• Treatment: IV cefotaxime + IV albumin (prevents HRS)

G. Hepatopulmonary Syndrome & Portopulmonary Hypertension

• Hepatopulmonary: intrapulmonary vascular dilation → hypoxemia
• Portopulmonary: pulmonary arterial hypertension from portal hypertension

H. Coagulopathy

• Decreased synthesis of coagulation factors (I, II, V, VII, VIII, IX, X, XI)
• Factor V (shortest half-life) is the most sensitive marker for acute deterioration
• INR elevation reflects synthetic dysfunction

8. Acute Liver Failure (ALF)

• ICU admission; address neurologic, respiratory, hemodynamic, infectious, and renal complications
• N-acetylcysteine (NAC): 140 mg/kg loading dose → 70 mg/kg q4h for acetaminophen toxicity; also used in non-acetaminophen ALF (especially grade 1-2 encephalopathy)
• Cause-specific: nucleoside analogues for HBV, acyclovir for HSV, copper chelation for Wilson's
• King's College Criteria or MELD score to determine transplant listing priority

9. Other Important Liver Diseases

Autoimmune Hepatitis (AIH)

• Predominantly affects women; associated with HLA-DR3 and DR4
• Labs: elevated IgG, ANA and/or anti-smooth muscle antibodies (Type 1); anti-LKM1 (Type 2)
• Treatment: prednisolone ± azathioprine

Primary Biliary Cholangitis (PBC)

• Chronic cholestatic disease; autoimmune destruction of intrahepatic bile ducts
• Anti-mitochondrial antibodies (AMA-M2) in >90% of cases
• Treatment: ursodeoxycholic acid (UDCA)

Primary Sclerosing Cholangitis (PSC)

• Fibro-inflammatory stricturing of bile ducts; strongly associated with IBD (especially UC)
• Elevated ALP, characteristic "beading" on MRCP/ERCP
• No effective medical therapy; liver transplant for end-stage disease

Hereditary Hemochromatosis

• Autosomal recessive (HFE gene mutations C282Y, H63D)
• Iron deposition in liver, heart, pancreas, joints, pituitary
• Complications: cirrhosis, HCC, diabetes, cardiomyopathy
• Treatment: therapeutic phlebotomy

Wilson's Disease

• Autosomal recessive (ATP7B mutations); copper accumulation
• Manifestations: liver disease, neuropsychiatric symptoms, Kayser-Fleischer rings
• Labs: low ceruloplasmin, elevated 24-hr urine copper
• Treatment: D-penicillamine, trientine, or zinc

α1-Antitrypsin Deficiency

• PiZZ phenotype most common; abnormal protein accumulates in hepatocytes
• Causes cirrhosis and emphysema
• Treatment: liver transplant for end-stage disease

10. Assessment of Liver Disease Severity

Child-Pugh Score

• Class A (5-6): compensated; good prognosis
• Class B (7-9): moderate compromise
• Class C (10-15): decompensated; poor prognosis

MELD Score (Model for End-Stage Liver Disease)

• Formula: 3.78(ln serum bilirubin mg/dL) + 11.2(ln INR) + 9.57(ln serum creatinine mg/dL) + 6.43
• Predicts 90-day mortality; used for transplant organ allocation
• MELD ≤6 or UKELD ≤42 - low risk of liver-related complications during pregnancy

Laboratory Tests

11. Hepatocellular Carcinoma (HCC)

• Most common primary liver malignancy
• Risk factors: HBV, HCV, cirrhosis (of any cause), NAFLD/NASH, aflatoxin, alcohol, metabolic syndrome
• HCC is the most rapidly increasing neoplasm in the United States (10,000-12,000 deaths/year)
• Surveillance: ultrasound ± AFP every 6 months in high-risk patients
• Diagnosis confirmed by multiphasic CT or MRI (arterial enhancement + portal washout = LI-RADS 5)
• Treatment: curative resection, ablation, TACE, sorafenib/lenvatinib, liver transplant (Milan criteria)

12. Liver Transplantation

• Decompensated cirrhosis (MELD ≥15-18)
• HCC within Milan criteria (single tumor ≤5cm or ≤3 tumors all ≤3cm)
• Acute liver failure
• Metabolic liver diseases (Wilson's, α1-AT deficiency, etc.)

Recent Evidence (2024-2025)

• A 2025 meta-analysis on alcohol-associated hepatitis confirmed high short-term mortality and identified key risk factors
• AI/machine learning in MASLD risk stratification is an active area per a 2026 systematic review (PMID 40850679)
• MASLD (metabolic dysfunction-associated steatotic liver disease) is the new preferred terminology replacing NAFLD in 2023 guidelines

Summary

1. Identify and remove the cause (abstinence, antivirals, immunosuppression, chelation)
2. Manage complications of portal hypertension and synthetic dysfunction
3. Monitor for HCC with regular surveillance
4. Transplant in appropriately selected patients with end-stage disease

• Schwartz's Principles of Surgery, 11e
• Robbins & Kumar Basic Pathology
• Goldman-Cecil Medicine, International Edition
• Yamada's Textbook of Gastroenterology, 7e
• Symptom to Diagnosis: An Evidence-Based Guide, 4e
• Sleisenger and Fordtran's Gastrointestinal and Liver Disease