Diagnosing Alcohol-Induced Liver Disease
The diagnosis of alcohol-induced liver disease requires documented excessive alcohol consumption (>40 g/day in men, >20 g/day in women) combined with evidence of liver injury, while excluding other causes of liver disease. 1
Key Diagnostic Laboratory Patterns
The AST/ALT ratio is the most characteristic laboratory finding in ALD:
- AST/ALT ratio >2 is seen in approximately 70% of patients with ALD 1
- AST/ALT ratio >3 is highly suggestive of alcoholic liver disease 1
- AST and ALT levels typically remain below 300 IU/L in ALD 1
- AST >500 IU/L or ALT >200 IU/L should prompt investigation for alternative diagnoses (except in cases of acetaminophen overdose or alcoholic foamy degeneration) 1
Supporting Laboratory Markers
Combining multiple biomarkers improves diagnostic accuracy over any single test: 1
- Gamma-glutamyl transferase (GGT) is elevated in approximately 75% of habitual drinkers, useful for monitoring abstinence but has low specificity 1
- Mean corpuscular volume (MCV) elevation occurs with daily consumption exceeding 60 g; sensitivity increases when combined with elevated GGT 1
- Carbohydrate-deficient transferrin (CDT) has high specificity but low sensitivity (25-50%), with a half-life of 2-3 weeks 1
- No single biomarker is adequate to establish alcohol use in ALD 1, 2
Clinical Assessment
Document alcohol consumption history thoroughly: 1
- Quantify daily alcohol intake in grams (refer to standardized alcohol content tables) 1
- Screen using validated tools like AUDIT questionnaire (score ≥8 in men up to age 60, or ≥4 in women/elderly indicates positive screen) 1
- Assess for alcohol use disorder criteria (≥2 symptoms indicates AUD) 1, 2
Physical examination findings more commonly seen in ALD include: 1
- Parotid enlargement
- Dupuytren's contracture
- Signs of feminization (gynecomastia, spider angiomas)
- However, no physical finding is 100% specific or sensitive for ALD 1
Imaging Studies
Imaging cannot establish alcohol as the specific etiology but serves to: 1
- Identify hepatic steatosis (ultrasound is useful first-line) 1
- Exclude alternative diagnoses (biliary obstruction, hepatocellular carcinoma, infiltrative disease) 1
- Assess for cirrhosis and complications (splenomegaly, portal hypertension) 1
- Transient elastography (FibroScan) can identify advanced fibrosis/cirrhosis with ~95% accuracy 3
Liver Biopsy Indications
Liver biopsy is not essential for diagnosis but is valuable in specific situations: 1
- Approximately 20% of patients with suspected ALD have alternative or coexisting etiologies 1
- Only 70-80% of patients with presumed alcoholic hepatitis have histologic confirmation 1
- Consider biopsy when contemplating high-risk treatments (e.g., corticosteroids for severe alcoholic hepatitis) 1
- Useful for staging disease severity and determining prognosis 1
Characteristic histologic features include: 1
- Macrovesicular steatosis (starting in centrilobular zone) 1
- Mallory-Denk bodies (eosinophilic cytoplasmic inclusions) 1
- Polymorphonuclear cell infiltration 1
- Perivenular and pericellular fibrosis 1
- Ballooning degeneration of hepatocytes 1
- These features are not individually pathognomonic and can occur in other conditions 1
Critical Pitfalls to Avoid
- Do not rely on GGT alone - it lacks specificity and can be elevated in non-alcoholic liver disease, obesity, diabetes, smoking, and drug use 1
- Conventional screening (ultrasound and routine labs) can miss up to 40% of manifest alcoholic cirrhosis 3
- Always exclude viral hepatitis, non-alcoholic fatty liver disease, drug-induced liver injury, and hemochromatosis 1
- Patients frequently underreport alcohol consumption - use objective biomarkers and validated screening tools 4
- Interpret liver stiffness measurements cautiously - requires concurrent ultrasound and current transaminase levels for accurate interpretation 3