What are the recommended lab tests and treatments for alcohol use disorder?

Laboratory Evaluation for Alcohol Use Disorder

All patients with suspected alcohol use disorder require a comprehensive metabolic panel, complete blood count, liver function tests (AST, ALT, GGT, alkaline phosphatase, bilirubin, albumin, prothrombin time), and screening for viral hepatitis (anti-HCV, HBsAg, anti-HBc). 1, 2

Initial Screening and Alcohol Use Assessment

Screen all adults 18 years and older for alcohol use disorders using validated questionnaires before ordering laboratory tests. 1

• Use the AUDIT (Alcohol Use Disorders Identification Test), AUDIT-C (3-question version), or NIAAA single-question screening: "How many times in the past year have you had 4 or more drinks (women) or 5 or more drinks (men) in a day?" 1
• A response of one or more times warrants follow-up and laboratory evaluation 1
• Critical pitfall: Patients routinely underreport alcohol consumption by 40-60%, making laboratory biomarkers essential adjuncts to clinical interview 1, 2

Essential Laboratory Panel

Liver Function Tests

• AST/ALT ratio >1.5-2.0 is highly suggestive of alcoholic liver disease, with ratios >3 being nearly diagnostic 2
• In approximately 70% of alcoholic hepatitis cases, the AST/ALT ratio exceeds 2 2
• AST levels rarely exceed 300 IU/L in pure alcoholic liver disease; levels >500 IU/L or ALT >200 IU/L suggest alternative or concurrent etiologies 2
• Important caveat: 80-90% of heavy drinkers develop fatty liver, but laboratory abnormalities may be minimal or absent in early disease 2
• GGT detects 34-85% of problem drinkers but lacks specificity for alcohol use alone 1, 2

Hematologic Testing

• Mean corpuscular volume (MCV) is commonly elevated in chronic alcohol use 2, 3
• Platelet count may be decreased, indicating advanced liver disease or direct alcohol toxicity 2
• Neutrophilia may be present, particularly in alcoholic hepatitis 2

Comprehensive Metabolic Panel

• Obtain glucose, electrolytes, blood urea nitrogen, and creatinine 2
• Calculate FIB-4 score using AST, ALT, platelets, and age to assess for advanced fibrosis 1

Alcohol-Specific Biomarkers

Phosphatidylethanol (PEth) in whole blood is the most sensitive and specific biomarker for detecting alcohol use, with a detection window of up to 12 days for a single episode and 6 weeks for chronic heavy use. 1

• PEth threshold of 20 ng/mL is the minimum reporting threshold for a positive test 1
• PEth levels directly correlate with the amount of alcohol consumed 1
• PEth is reliable in advanced liver disease, unlike other biomarkers 1

Alternative Biomarkers (When PEth Unavailable)

• Urinary ethyl glucuronide (EtG) and ethyl sulfate (EtS) detect alcohol use within 3 days, with sensitivity of 89% and specificity of 99% 1
• Warning: EtG and EtS detection times are prolonged in renal failure 1
• Carbohydrate-deficient transferrin (CDT) has low sensitivity (25-50%) and produces false-positives in severe liver disease without alcohol use 1
• Do not rely on GGT, MCV, or liver enzymes alone to confirm or refute alcohol use 1

Screening for Comorbid Conditions

Viral Hepatitis Screening (Mandatory)

• Anti-HCV testing is essential, as hepatitis C and alcohol have synergistic effects resulting in more advanced liver disease than either alone 2
• Test HBsAg and anti-HBc for hepatitis B, particularly in endemic populations 2
• Anti-HIV testing in at-risk individuals, as 6-13% of HIV-infected persons are coinfected with HBV 2

Additional Testing in High-Risk Patients

• Alpha-fetoprotein (AFP) and abdominal ultrasound for hepatocellular carcinoma screening in patients with cirrhosis 2
• Non-invasive fibrosis markers (FIB-4 score, NAFLD Fibrosis Score) to screen for advanced liver disease 1, 2

Severity Assessment for Alcohol Withdrawal

Use the Clinical Institute Withdrawal Assessment for Alcohol-Revised (CIWA-Ar) scale to assess withdrawal severity and guide treatment decisions. 4

• CIWA-Ar score >8 indicates moderate withdrawal requiring intervention 4
• CIWA-Ar score ≥15 indicates severe withdrawal with 3.72-fold increased risk of seizures and delirium tremens 4
• This scale is distinct from AUDIT, which screens for alcohol use disorder, not withdrawal 4

Common Pitfalls to Avoid

• Never use a single biomarker in isolation; combine laboratory testing with clinical interview and validated questionnaires 1
• Do not assume normal liver enzymes exclude alcoholic liver disease—early disease may have minimal laboratory abnormalities 2
• Remember that high AST/ALT ratios indicate advanced liver disease, not just heavy drinking 5
• Discuss biomarker use with patients before testing to maintain therapeutic alliance and improve disclosure 1
• Consider that women may have higher PEth levels than men at equivalent alcohol consumption 1