title: Excess serum osmolality gap after ingestion of methanol: a methodology-associated phenomenon?
abstract: A patient intentionally ingested an unknown amount of methanol and was admitted to the hospital 6 h later. On admission, the methanol concentration in blood was estimated as approximately of 134 mmol/L, based on the calculation of the osmolal gap. Intravenous ethanol administration and hemodialysis were promptly started. During hemodialysis, several blood samples were collected for determination of methanol and ethanol concentrations. Initially, we used gas chromatography with split-mode injection of pretreated serum samples; however, methanol concentrations turned out to be significantly lower than expected, based on calculated osmolal gap values. Because no explanation for the excess serum osmolal gap was apparent, we reanalyzed samples, using head-space gas chromatography. The methanol concentrations measured were significantly higher and osmolal gap values were no longer excessive.
authors.affiliation: Laboratory of Clinical Chemistry and Toxicology, Algemeen Ziekenhuis Middelheim, Antwerpen, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: Demedts
authors.forename: L
authors.initials: L
authors.lastname: Theunis
authors.forename: A
authors.initials: A
authors.lastname: Wauters
authors.forename: F
authors.initials: F
authors.lastname: Franck
authors.forename: R
authors.initials: R
authors.lastname: Daelemans
authors.forename: H
authors.initials: H
authors.lastname: Neels
mesh_terms: D000138:Acidosis / Q000097:blood / Q000209:etiology; D000328:Adult; D000431:Ethanol / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use; D005189:False Positive Reactions; D006801:Humans; D008297:Male; D000432:Methanol / Q000097:blood / Q000506:poisoning*; D009994:Osmolar Concentration; D006435:Renal Dialysis; D013406:Suicide, Attempted
chemical_list: D000431:Ethanol; D000432:Methanol