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

Laboratory Testing for Patients with Alcohol Abuse

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

Essential Core Laboratory Panel

Liver Function Tests

• AST, ALT, GGT, alkaline phosphatase, bilirubin, albumin, and prothrombin time form the foundation of your assessment for alcohol-related liver damage 1
• An AST/ALT ratio >2 is highly suggestive of alcoholic liver disease, with ratios >3 being particularly specific 1, 2
• AST levels rarely exceed 300 IU/L in pure alcoholic hepatitis; levels >500 IU/L or ALT >200 IU/L should prompt evaluation for alternative diagnoses 1
• GGT detects 34-85% of problem drinkers but lacks specificity for screening purposes alone 1

Hematologic Assessment

• Obtain a complete blood count with mean corpuscular volume (MCV), which is commonly elevated in chronic alcohol use 1
• Platelet count may be decreased, indicating advanced liver disease or direct alcohol toxicity 1
• Neutrophilia may be present, particularly in alcoholic hepatitis 1
• Elevated MCV combined with elevated GGT improves sensitivity for detecting chronic alcohol use 2

Metabolic and Electrolyte Panel

• A comprehensive metabolic panel including glucose, electrolytes, BUN, and creatinine is mandatory 1, 2
• Hypoglycemia is the most frequently identified unexpected laboratory abnormality 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

• Test for hepatitis C (anti-HCV), hepatitis B (HBsAg and anti-HBc), and consider HIV testing in at-risk individuals 1
• Hepatitis C and alcohol have a synergistic relationship resulting in more advanced liver disease than either alone 1
• 6-13% of HIV-infected persons are coinfected with HBV, affecting liver disease progression 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

Alcohol-Specific Biomarkers (When Monitoring Abstinence)

When to Use Biomarkers

• Biomarkers are NOT recommended for systematic screening—use AUDIT questionnaires instead 1, 3
• Biomarkers are appropriate when you need objective confirmation of alcohol use, particularly when patients dispute results or underreport consumption 1, 3

Phosphatidylethanol (PEth)

• 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 1, 3
• A 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 and remain reliable in advanced liver disease 1

Urinary Ethyl Glucuronide (EtG) and Ethyl Sulfate (EtS)

• EtG and EtS detect alcohol use within 3 days with 89% sensitivity and 99% specificity 1, 3
• Detection times are prolonged in renal failure 1

Carbohydrate-Deficient Transferrin (CDT)

• Do not rely on CDT alone—it has low sensitivity (25-50%) and produces false-positives in severe liver disease without alcohol use 1

Nutritional Deficiency Assessment

• Order thiamine level, vitamin B12, and folate to identify reversible causes of cognitive impairment and assess for alcohol-related nutritional deficiencies 2

Hepatocellular Carcinoma Screening in High-Risk Patients

• Obtain baseline alpha-fetoprotein (AFP) and ultrasound in high-risk patients for hepatocellular carcinoma screening 1

Critical Clinical Pitfalls to Avoid

• Never rely on laboratory tests alone—always combine with structured screening questionnaires like AUDIT because patients routinely underreport consumption 1, 3, 2
• 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 due to limited sensitivity 2
• Discuss biomarker use with patients before testing to maintain therapeutic alliance and improve disclosure 1
• Women may have higher PEth levels than men at equivalent alcohol consumption 1

Documentation Requirements

• When ordering definitive testing or biomarkers, document specific clinical indication requiring confirmation 3
• Generic statements about monitoring compliance are insufficient—specify which substances and why 3
• Results should directly inform treatment modifications or medication management decisions 3