Background: We describe a case of acute propylene glycol toxicity following ingestion of ethanol and propylene glycol-containing antifreeze in which blood lactate, serum propylene glycol, ethanol, and CO2 concentrations were serially measured.
Case report: A 61-year-old man was hospitalized after acute ingestion of ethanol and automotive antifreeze. His clinical presentation and course were essentially unremarkable. Initial lab tests revealed serum ethanol concentration, 167 mg/dL, normal serum electrolytes and osmol gap, 120 mOsm/kg. Intravenous 10% ethanol infusion was begun for suspected ethylene glycol toxicity and discontinued at approximately 17 hours post-ingestion. Toxicological analysis of urine was positive for ethanol and propylene glycol, and negative for ethylene glycol, methanol, and isopropanol. Blood lactate was mildly elevated and serum CO2 concentration was normal. Gas chromatographic analysis of serial serum specimens for propylene glycol concentration revealed a maximum value of 470 mg/dL at 7 hours and a nonlinear decline to below detection limit (3 mg/dL) at 57 hours after antifreeze ingestion. The patient was discharged on hospital day 2.
Conclusion: The propylene glycol elimination pattern, absence of significant acid-base disturbance, and minimal lactate elevation in this case are consistent with ethanol-related inhibition of propylene glycol metabolism. The effect of ethanol on clinical outcome after acute propylene glycol intoxication remains uncertain.