What labs should be ordered for someone with alcohol use disorder?

Laboratory Testing for Alcohol Use Disorder

Order a comprehensive metabolic panel, complete blood count with MCV, liver function tests (AST, ALT, GGT, alkaline phosphatase, bilirubin, albumin, PT/INR), and viral hepatitis screening (anti-HCV, HBsAg, anti-HBc) for all patients with alcohol use disorder. 1

Essential Liver Function Panel

The cornerstone of laboratory evaluation focuses on detecting alcoholic liver disease, which causes 14.6% mortality with major complications including variceal bleeding (31.1%), liver failure (24.5%), and hepatorenal syndrome/sepsis (11.3%). 2

Core liver tests to order: 1

• AST and ALT: An AST/ALT ratio >1.5-2.0 strongly suggests alcoholic liver disease, particularly when AST is elevated but rarely exceeds 300 IU/mL 1, 2
• GGT (gamma-glutamyl transpeptidase): The most widely used marker, detecting 34-85% of problem drinkers, though limited by poor specificity 1
• Alkaline phosphatase, total and direct bilirubin: Essential for assessing cholestasis and severity 1
• Albumin and prothrombin time/INR: Critical markers of hepatic synthetic function and disease severity 1

Key Diagnostic Pattern

In approximately 70% of alcoholic hepatitis cases, the AST/ALT ratio exceeds 2, with ratios >3 being highly suggestive of alcoholic liver disease. 2 However, AST levels >500 IU/L or ALT >200 IU/L are uncommon in pure alcoholic hepatitis and should prompt evaluation for alternative or concurrent etiologies. 2

Hematologic Assessment

Complete blood count with differential: 1

• Mean corpuscular volume (MCV): Commonly elevated in chronic alcohol use and serves as a useful screening marker 1
• Platelet count: Decreased levels indicate advanced liver disease or direct alcohol toxicity 1
• White blood cell count: Neutrophilia may be present, particularly in alcoholic hepatitis 1

Metabolic and Electrolyte Evaluation

Comprehensive metabolic panel including: 1

• Glucose (assess for hypoglycemia or diabetes)
• Electrolytes (sodium, potassium, chloride, bicarbonate)
• Blood urea nitrogen and creatinine (evaluate renal function and hepatorenal syndrome risk)

Mandatory Viral Hepatitis Screening

Coinfection with viral hepatitis dramatically worsens outcomes and requires different management strategies. 1

Required viral testing: 1

• Anti-HCV antibody: Hepatitis C and alcohol have a synergistic relationship resulting in more advanced liver disease than either alone 1
• HBsAg and anti-HBc: Screen for hepatitis B, particularly in endemic populations 1
• Anti-HIV: Recommended in at-risk individuals, as 6-13% of HIV-infected persons are coinfected with HBV, affecting liver disease progression 1

Additional Specialized Testing

For advanced disease assessment: 1

• Non-invasive fibrosis markers: Use to screen for advanced liver disease without immediate biopsy 1
• Alpha-fetoprotein (AFP) and liver ultrasound: Baseline screening for hepatocellular carcinoma in high-risk patients 1

For monitoring abstinence: 1

• Ethyl glucuronide (EtG): Can be measured in urine or hair to accurately monitor abstinence, as patients commonly underreport alcohol consumption 1

Critical Clinical Pitfalls

Avoid relying solely on biomarkers for diagnosis. While GGT has been evaluated in large population surveys, its low sensitivity and specificity limit usefulness for diagnosing alcohol abuse. 2 Carbohydrate-deficient transferrin has been studied but also lacks adequate sensitivity and specificity, with results influenced by age, sex, body mass index, and other chronic liver diseases. 2

Always combine laboratory testing with structured screening questionnaires like AUDIT (score ≥8 indicates positive screen), as patients routinely underreport consumption. 2, 1 The combination of quantitative alcohol history, heavy drinking days assessment, and AUDIT scoring provides superior diagnostic accuracy compared to laboratory markers alone. 2

Remember that 80-90% of heavy drinkers develop fatty liver, but laboratory abnormalities may be minimal or absent in early alcoholic liver disease. 2 Normal laboratory values do not exclude significant alcohol use disorder or early liver injury. 3