What lab values are concerning in alcohol poisoning?

Lab Values Concerning in Alcohol Poisoning

In acute alcohol poisoning, the most critical lab values to assess are blood alcohol concentration (BAC), blood glucose, arterial blood gas with pH and lactate, electrolytes (particularly sodium and potassium), and osmolar gap—with BAC >1 g/L (100 mg/dL) indicating severe intoxication requiring aggressive supportive care. 1, 2

Blood Alcohol Concentration (BAC)

• BAC >1 g/L (>100 mg/dL) defines severe intoxication and necessitates intravenous fluid support, treatment of hypoglycemia, hypotension, hypothermia, electrolyte imbalances, and administration of B and C vitamins 1
• BAC <1 g/L typically represents mild-moderate intoxication where supportive care alone is sufficient without pharmacologic intervention 1
• BAC measurement is essential both for clinical management and legal documentation 2
• The extent of intoxication depends not only on BAC but also on individual metabolic differences, making clinical assessment paramount 1

Metabolic Parameters

• Blood glucose must be checked immediately as hypoglycemia is a common and dangerous complication requiring urgent correction 1
• Arterial blood gas with pH and serum lactate should be obtained to assess for metabolic acidosis, which may indicate severe intoxication or complications 3
• Severe acidosis (low pH, elevated lactate) can indicate life-threatening complications 3

Electrolyte Abnormalities

• Sodium, potassium, chloride, magnesium, and calcium should be measured as alcohol intoxication can cause significant electrolyte derangements 3
• Hyponatremia, hypokalemia, and other imbalances require specific correction 3

Liver Function and Hematologic Markers

• AST and ALT should be checked, particularly in patients with chronic alcohol use, where AST/ALT ratio >2 suggests underlying alcoholic liver disease 4, 5
• GGT (gamma-glutamyltransferase) is the most sensitive marker for detecting habitual alcohol consumption, elevated in approximately 75% of chronic drinkers 5
• MCV (mean corpuscular volume) elevation is common in heavy drinkers consuming >60g daily and provides additional evidence of chronic alcohol use 6
• The combination of elevated MCV and GGT provides better sensitivity for detecting chronic alcohol abuse than either test alone 6

Additional Essential Labs

• Complete blood count (CBC) to assess for anemia, thrombocytopenia (which predicts poor outcomes), and leukocytosis 3
• Renal function (urea, creatinine) as renal failure is predictive of poor outcomes 3
• β-HCG in women of childbearing age to rule out pregnancy 3
• Osmolar gap calculation to screen for co-ingestion of toxic alcohols (methanol, ethylene glycol) which can be life-threatening 7, 8

Critical Pitfalls to Avoid

• Never rely solely on BAC to guide management—clinical presentation and vital signs are equally important as individual tolerance varies significantly 9, 1
• Always check blood glucose immediately as hypoglycemia can mimic or worsen alcohol intoxication and is rapidly reversible 1
• Consider toxic alcohol co-ingestion if there is unexplained metabolic acidosis with elevated osmolar gap, as this requires specific antidotal therapy (fomepizole) and potentially hemodialysis 7, 8
• GGT elevation is not specific to alcohol—it can be elevated in non-alcoholic liver disease, obesity, diabetes, smoking, or drug use, requiring careful interpretation 6
• Adolescents are more vulnerable to alcohol's toxic effects due to immature hepatic alcohol dehydrogenase activity, making complications more frequent and dangerous in young people 1

Monitoring During Observation

• Serial vital signs monitoring is essential to detect development of alcohol withdrawal syndrome and evaluate for pathological complications, particularly acute liver damage 1
• Most patients with mild-moderate intoxication can be managed in a temporary observation unit with clinical monitoring, with resolution typically within 24 hours 1