Excess serum osmolality gap after ingestion of methanol.

Two cases of methanol ingestion and one case of combined methanol and ethylene glycol ingestion are presented to illustrate the large differences that exist between the serum osmolality gap and the measured methanol (plus ethylene glycol) concentration(s) before treatment of these poisonings. After treatment with intravenous ethanol and hemodialysis was initiated, the differences disappeared in all three cases. We speculate that one or more metabolites with osmotic activity are formed in cases of methanol intoxication where no ethanol has also been consumed. The possible identity of these compounds is discussed.