Ethylene Glycol Poisoning with a Near-Normal Osmolal Gap: A Diagnostic Challenge

Ethylene glycol is a colorless, odorless, sweet-tasting liquid commonly found in antifreeze, as well as in industrial agents. It is regarded as one of the toxic alcohols. Ethylene glycol poisoning usually occurs due to ingestion, and its toxicity is mediated by its metabolites, glycolic acid, and oxalate. These metabolites can cause neurological symptoms, gastrointestinal symptoms, and/or renal failure if not diagnosed and treated promptly. The diagnosis can be very challenging as the test used to detect ethylene glycol in the blood may not be readily available or due to an inaccurate history. The treatment of ethylene glycol poisoning consists of supportive care, sodium bicarbonate, and the use of an antidote (ethanol or fomepizole) which inhibits alcohol dehydrogenase and thereby prevents the formation of toxic metabolites. Patients with advanced poisonings may also require dialysis. The diagnosis is usually suggested by a high anion gap metabolic acidosis and an elevated osmolal gap in the setting of a suspected ingestion. Rarely, the osmolal gap may be close to normal which can delay the diagnosis or lead to a misdiagnosis. We report a case of ethylene glycol ingestion with a near-normal osmolal gap.