Acquired 5-Oxoprolinuria (Pyroglutamic Acidaemia) as a Cause of Early High Anion Gap Metabolic Acidosis in Acute Massive Paracetamol Overdose

Abstract

5-oxoprolinuria is an uncommon and under-recognised cause of early high anion gap metabolic acidosis after paracetamol overdose. We reported a 30-year-old Indian woman with history of chronic alcoholism who ingested 150 g crushed paracetamol tablets for suicide 14 hours before attendance to the A&E Department. Initial arterial blood gas showed a high anion gap metabolic acidosis with respiratory compensation. Serum paracetamol level reached 5004 umol/L and a prolonged course of N-acetylcysteine was given. She was complicated by hepatotoxicity and 5-oxoprolinuria (with laboratory confirmation) which reverted after antidote administration. There were no neurological and hepatic sequelae. In case of massive overdose, pathways of drug metabolism are altered prior to the centrilobular hepatic necrosis. A metabolic intermediate of gamma-glutamyl cycle, 5-oxoproline, accumulates upon saturation of endogenous glutathione store. The specific antidote N-acetylcysteine is the only definitive treatment. Prolonged course of antidote may be required in cases of massive overdose and treatment should be individualised. (Hong Kong j.emerg. med. 2011;18:264-270)