What labs should be ordered for an adult patient undergoing alcohol detox?

Laboratory Testing for Alcohol Detoxification Patients

For patients undergoing alcohol detoxification, order a comprehensive metabolic panel, complete blood count, liver function tests (AST, ALT, GGT, alkaline phosphatase, bilirubin, albumin, prothrombin time), magnesium, phosphate, and consider hepatitis B/C and HIV screening. 1, 2

Essential Initial Laboratory Panel

Metabolic and Electrolyte Assessment

• Comprehensive metabolic panel including glucose, sodium, potassium, chloride, blood urea nitrogen, and creatinine is essential, as alcohol intoxication causes significant electrolyte derangements that can complicate withdrawal. 3, 2
• Magnesium, calcium, and phosphate should be measured separately, as these are frequently depleted in chronic alcohol use and deficiencies can precipitate seizures during withdrawal. 3
• Arterial blood gas with pH and serum lactate if the patient appears severely ill or has altered mental status, to assess for metabolic acidosis indicating severe intoxication or complications. 3

Liver Function Assessment

• AST, ALT, GGT, alkaline phosphatase, bilirubin, albumin, and prothrombin time form the complete liver panel needed to assess for alcoholic liver disease and guide prognosis. 1, 2
• AST/ALT ratio >2 is highly suggestive of alcoholic liver disease, with ratios >3 being particularly specific; however, AST and ALT rarely exceed 300 IU/L in pure alcoholic hepatitis. 1, 2
• GGT is elevated in approximately 75% of habitual drinkers and was the most commonly elevated laboratory test in detoxification admissions, making it useful for confirming chronic alcohol use. 1, 3, 4

Hematologic Testing

• Complete blood count is essential to assess for anemia, thrombocytopenia (suggesting advanced liver disease), leukocytosis, and neutrophilia (particularly in alcoholic hepatitis). 3, 2
• Mean corpuscular volume (MCV) is commonly elevated in heavy drinkers consuming >60g daily and provides additional evidence of chronic alcohol use, though it takes months to normalize after abstinence. 1, 3, 2

Risk Stratification and Advanced Testing

Fibrosis Assessment

• Calculate FIB-4 score using AST, ALT, platelets, and age to assess for advanced fibrosis non-invasively; this should be incorporated into primary care computer systems for all patients with suspected alcoholic liver disease. 1, 2
• Fibroscan/ARFI elastography should be considered for harmful drinkers as part of risk stratification, with readings >16 kPa warranting referral to secondary care for advanced liver disease. 1

Viral Hepatitis and HIV Screening

• Anti-HCV, HBsAg, and anti-HBc testing is recommended because hepatitis C and alcohol have a synergistic relationship resulting in more advanced liver disease than either alone. 2
• Anti-HIV testing should be performed in at-risk individuals, as 6-13% of HIV-infected persons are coinfected with HBV, affecting liver disease progression. 2

Alcohol-Specific Biomarkers (When Clinically Indicated)

When to Use Biomarkers

• Biomarkers are NOT recommended for systematic screening of alcohol use disorder—validated questionnaires like AUDIT are the preferred screening method. 1, 5, 2
• Biomarkers are appropriate when objective confirmation of recent alcohol use is needed to inform specific treatment decisions or when patients dispute self-reported abstinence. 5, 2

Specific Biomarker Options

• Phosphatidylethanol (PEth) in whole blood is the most sensitive and specific biomarker, with detection windows up to 12 days for single episodes and 6 weeks for chronic heavy use; it remains reliable even in advanced liver disease. 5, 2
• Urinary ethyl glucuronide (EtG) and ethyl sulfate (EtS) detect alcohol use within 3 days with 89% sensitivity and 99% specificity, though detection times are prolonged in renal failure. 5, 2
• Carbohydrate-deficient transferrin (CDT) has low sensitivity (25-50%) and produces false-positives in severe liver disease, making it less useful than PEth or EtG. 2

Critical Clinical Pitfalls to Avoid

• Over 90% of detoxification patients have one or more abnormal laboratory values, so normal labs do not rule out significant alcohol use disorder or the need for detoxification. 4
• Patients routinely underreport alcohol consumption; always combine laboratory testing with structured screening questionnaires like AUDIT rather than relying on self-report alone. 5, 2
• Never use a single biomarker in isolation—combine laboratory testing with clinical interview and validated questionnaires to maintain diagnostic accuracy. 2
• 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 such as acetaminophen toxicity or viral hepatitis. 2
• 80-90% of heavy drinkers develop fatty liver, but laboratory abnormalities may be minimal or absent in early alcoholic liver disease, so clinical suspicion should guide management even with normal labs. 2
• Detection and monitoring within the first 24 hours is the most important element in management, as delays in assessment >24 hours significantly increase the risk of complications including seizures, hallucinations, and delirium. 6