Management of Alcohol Intoxication with Elevated Anion Gap
Immediate Assessment and Differentiation
The management of alcohol intoxication with an elevated anion gap depends critically on which toxic alcohol is involved—ethylene glycol and methanol require urgent hemodialysis and fomepizole, while ethanol and isopropanol intoxication are managed supportively. 1
Initial Diagnostic Workup
- Calculate the anion gap using Na+ + K+ - Cl- - HCO3- to quantify the severity 1
- Obtain arterial blood gases to assess pH and degree of metabolic acidosis 1
- Measure serum osmolal gap (measured osmolality minus calculated osmolarity) as toxic alcohols elevate this parameter 2, 3
- Check plasma glucose, serum ketones, and urine ketones immediately to distinguish diabetic ketoacidosis from alcoholic ketoacidosis 1
- Obtain blood alcohol levels for ethanol, methanol, ethylene glycol, and isopropanol if available 3, 4
- Order complete metabolic panel, BUN/creatinine, and urinalysis to assess for acute kidney injury and calcium oxalate crystals (ethylene glycol) 1, 5
Critical Diagnostic Pitfall
- A normal anion gap and osmolal gap does NOT rule out toxic alcohol poisoning, particularly if ethanol is co-ingested, as ethanol inhibits alcohol dehydrogenase and delays formation of toxic metabolites 6
- The anion gap may overestimate severity with concurrent AKI or ketoacidosis, or underestimate it with hypoalbuminemia 7, 1
Ethylene Glycol or Methanol Poisoning
Immediate Interventions
Begin fomepizole treatment immediately upon suspicion based on history, anion gap metabolic acidosis, increased osmolal gap, visual disturbances (methanol), or oxalate crystals in urine (ethylene glycol), without waiting for confirmatory levels 5
- Loading dose: 15 mg/kg IV over 30 minutes 5
- Maintenance: 10 mg/kg IV every 12 hours for 4 doses, then 15 mg/kg every 12 hours until toxic alcohol levels <20 mg/dL and patient asymptomatic with normal pH 5
Hemodialysis Indications (Strong Recommendations)
Initiate emergent hemodialysis if ANY of the following criteria are met:
- Anion gap >27 mmol/L with confirmed or suspected ethylene glycol exposure 7, 1
- Glycolate concentration >12 mmol/L (if available) 7
- Ethylene glycol or methanol concentration ≥50 mg/dL 7, 5
- Osmolal gap >50 when using ethanol as antidote 7
- Coma or seizures attributed to toxic alcohol 7
- Acute kidney injury (KDIGO stage 2 or 3) 7
- Significant or worsening metabolic acidosis despite supportive care 5
Consider Hemodialysis (Weaker Recommendations)
- Anion gap 23-27 mmol/L with suspected ethylene glycol exposure 7
- Glycolate concentration 8-12 mmol/L 7
- Osmolal gap >50 when using fomepizole 7
Hemodialysis Specifications
- Use intermittent hemodialysis as first-line modality when available (most efficient removal) 7
- Use high-flux membrane with blood flow >250 mL/min 2
- Use bicarbonate-based dialysate enriched with phosphorus and potassium to prevent electrolyte depletion 2
- Increase fomepizole dosing to every 4 hours during hemodialysis as it is dialyzable 5
Cessation of Hemodialysis
Stop hemodialysis when anion gap <18 mmol/L (strong recommendation) 7
- Alternatively, stop when ethylene glycol/methanol concentration <4 mmol/L (25 mg/dL) and patient asymptomatic with normal pH 7, 5
Alcoholic Ketoacidosis
Clinical Recognition
- Typically presents with glucose <250 mg/dL (often normal or hypoglycemic), distinguishing it from diabetic ketoacidosis 1
- History of chronic alcohol use with recent binge drinking and poor oral intake 8
Management
- Administer IV thiamine 100 mg before any dextrose-containing fluids 8
- Aggressive fluid resuscitation with 0.9% NaCl at 15-20 mL/kg/hour for first hour 1
- Add dextrose-containing fluids (D5W or D5 0.45% NaCl) once glucose normalizes to suppress ketogenesis 1
- Replete potassium, magnesium, and phosphate as needed 1
- Bicarbonate administration is rarely needed and resolves with fluid resuscitation 8
Ethanol Intoxication Alone
- Supportive care only with IV fluids, thiamine, and monitoring 3
- Ethanol itself does not cause significant anion gap elevation; if present, search for alternative causes 3, 4