Approach to possible ethylene glycol or methanol poisoning when confirmatory testing pending or not available

ADH: alcohol dehydrogenase; BUN: blood urea nitrogen; IV: intravenous; Na: sodium; PO: orally.

• If using mg/dL (conventional units) for glucose, BUN, ethanol: Osmolal gap = Measured osmolality – [(2 × Na) + glucose/18 + BUN/2.8 + ethanol/3.7]
• If using mmol/L (SI units) for glucose, BUN, ethanol: Osmolal gap = Measured osmolality – [(2 × Na) + glucose + BUN + (1.25 × ethanol)]

¶ In a patient with a witnessed ingestion or compelling history who presents within 2 hours of ingestion, the pH can be normal and the osmolal gap <10 mOsm/kg; thus, administer fomepizole until serum toxic alcohol concentrations result from laboratory. There is no immediate need for bicarbonate or hemodialysis while waiting for concentrations in this setting.

Δ Initial fomepizole dose is 15 mg/kg IV loading dose, followed by 10 mg/kg every 12 hours for 4 doses, then 15 mg/kg every 12 hours. If fomepizole is not available, can start ethanol IV or orally (refer to UpToDate content for instructions). If patient is receiving hemodialysis, refer to UpToDate content for increased fomepizole dosing frequency and ethanol infusion rate. If the patient has a serum ethanol concentration >100 mg/dL, fomepizole should be given once the serum ethanol decreases to approximately 100 mg/dL. Refer to UpToDate content on ethanol intoxication in adults for rate of ethanol elimination.

• Methanol: leucovorin 50 mg IV or folic acid 50 mg IV every 6 hours
• Ethylene glycol: thiamine 100 mg IV once daily and pyridoxine 100 mg IV once daily

§ Most hospitals do not offer these assays and must be sent to reference laboratory. Contact hospital lab to arrange fastest possible turnaround time.

• Estimated ethylene glycol concentration in mg/dL = Increase in osmolal gap × 6.2
• Estimated methanol concentration in mg/dL = Increase in osmolal gap × 3.2