What laboratory tests should be ordered for a patient with a history of excessive alcohol consumption?

Laboratory Testing for Patients with Alcohol Use

Order a comprehensive liver function panel (AST, ALT, GGT, alkaline phosphatase, bilirubin, albumin, PT/INR), complete blood count with MCV, comprehensive metabolic panel, and hepatitis C antibody testing as your initial laboratory workup. 1

Essential Initial Laboratory Panel

Liver Function Tests (Priority)

• AST, ALT, GGT, alkaline phosphatase, bilirubin, albumin, and prothrombin time are recommended by the American Association for the Study of Liver Diseases for all patients with alcoholism. 1
• An AST/ALT ratio >2 (especially >3) is highly suggestive of alcoholic liver disease, with AST typically elevated but rarely exceeding 300-500 IU/mL. 1, 2
• In approximately 70% of alcoholic hepatitis cases, the AST/ALT ratio exceeds 2. 1
• 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. 1
• GGT is the most widely used marker, detecting 34-85% of problem drinkers, though it lacks specificity and should not be used alone. 1

Hematologic Testing

• Mean corpuscular volume (MCV) is commonly elevated in chronic alcohol use and should be measured. 1
• Platelet count may be decreased, indicating advanced liver disease or direct alcohol toxicity. 1
• Elevated MCV combined with elevated GGT improves sensitivity for detecting chronic alcohol use and associated complications. 2

Metabolic Panel

• A comprehensive metabolic panel (glucose, electrolytes, BUN, creatinine) should be performed in all patients with alcoholism. 1
• Hypoglycemia is the most frequently identified unexpected laboratory abnormality in alcohol-related presentations and represents a rapidly reversible cause of altered cognition. 2
• Hyponatremia is the second most common metabolic abnormality and can contribute to cognitive dysfunction. 2

Viral Hepatitis Screening

• Anti-HCV testing is recommended by the American Association for the Study of Liver Diseases, as hepatitis C and alcohol have a synergistic relationship resulting in more advanced liver disease than either alone. 1
• HBsAg and anti-HBc should be tested for hepatitis B screening, particularly in endemic populations. 1
• Anti-HIV testing is recommended in at-risk individuals, as 6-13% of HIV-infected persons are coinfected with HBV. 1

Advanced Fibrosis Assessment

• Calculate the FIB-4 score using AST, ALT, platelets, and age to assess for advanced fibrosis. 1
• Non-invasive fibrosis markers should be used to screen for advanced liver disease. 1

Nutritional Deficiency Testing

• Thiamine level, vitamin B12, and folate levels should be considered to identify reversible causes of cognitive impairment and assess for alcohol-related organ damage. 2

Alcohol-Specific Biomarkers (When Monitoring Abstinence)

• Phosphatidylethanol (PEth) in whole blood is the most sensitive and specific biomarker for detecting alcohol use, with detection windows up to 12 days for single episodes and 6 weeks for chronic heavy use (threshold 20 ng/mL). 1
• PEth levels directly correlate with the amount of alcohol consumed and remain reliable in advanced liver disease, unlike other biomarkers. 1
• Urinary ethyl glucuronide (EtG) and ethyl sulfate (EtS) detect alcohol use within 3 days with 89% sensitivity and 99% specificity. 1
• Carbohydrate-deficient transferrin (CDT) has low sensitivity (25-50%) and produces false-positives in severe liver disease without alcohol use. 1

Critical Clinical Pitfalls to Avoid

• Never rely on GGT, MCV, or liver enzymes alone to confirm or refute alcohol use, as recommended by the American Association for the Study of Liver Diseases. 1
• 80-90% of heavy drinkers develop fatty liver, but laboratory abnormalities may be minimal or absent in early alcoholic liver disease. 1
• Normal GGT or MCV does not rule out significant alcohol-related pathology, as these markers have limited sensitivity. 2
• Always combine laboratory testing with structured screening questionnaires like AUDIT, as patients routinely underreport consumption. 1, 2
• Discuss biomarker use with patients before testing to maintain therapeutic alliance and improve disclosure. 1

Hepatocellular Carcinoma Screening in High-Risk Patients

• Alpha-fetoprotein (AFP) at baseline and ultrasound should be used for hepatocellular carcinoma screening in high-risk patients. 1