A retrospective analysis of glycol and toxic alcohol ingestion: utility of anion and osmolal gaps

Electronic medical records from an academic tertiary care medical center were searched to identify all patients in the time period from January 1, 1996 to September 1, 2010 who had serum/plasma ethanol, glucose, sodium, blood urea nitrogen, and osmolality measured simultaneously, and also all patients who had GC analysis for toxic alcohols. Detailed chart review was performed on all patients with osmolal gap of 9 or greater.In the study period, 20,669 patients had determination of serum/plasma ethanol and osmolal gap upon presentation to the hospitals. There were 341 patients with an osmolal gap greater than 14 (including correction for estimated contribution of ethanol) on initial presentation to the medical center. Seventy-seven patients tested positive by GC for one or more toxic alcohols; all had elevated anion gap or osmolal gap or both. Other than toxic alcohols, the most common causes for an elevated osmolal gap were recent heavy ethanol consumption with suspected alcoholic ketoacidosis, renal failure, shock, and recent administration of mannitol. Only 9 patients with osmolal gap greater than 50 and no patients with osmolal gap greater than 100 were found to be negative for toxic alcohols.Our study concurs with other investigations that show that osmolal gap can be a useful diagnostic test in conjunction with clinical history and physical examination.Consumption of toxic alcohols other than ethanol continues to be a public health problem [1]. The most common toxic alcohols are ethylene glycol, isopropanol, and methanol. All three compounds are found in products that are easily obtained (ethylene glycol in most automobile antifreezes, isopropanol in 'rubbing alcohol', and methanol in windshield cleaner fluid and some other products). Ethylene glycol and methanol are particularly dangerous in overdose, due to their metabolites that can cause severe organ damage [1-6].Ethylene glycol is metabolized by a series of steps to glycolic acids and oxalic acid, the latt