A not so simple analgesic.

Many of the common causes of a high anion gap metabolic acidosis, like salicylate toxicity or diabetic ketoacidosis, are well recognized and promptly treated. Pyroglutamic acidosis (or 5-oxoproline acidosis) is a less common cause and is likely substantially underdiagnosed for two reasons: firstly, urine or serum measurements of pyroglutamic acid are performed only in specialist laboratories, and secondly, because awareness of the condition is still low, despite widespread reports in the medical and biochemical literature. The condition is often precipitated by the chronic use of paracetamol. Paracetamol is increasingly being widely prescribed as an alternative to NSAIDs often in maximal doses, given its innocuous reputation, and we anticipate more similar presentations. We present a case of a young pregnant woman who developed a severe metabolic acidosis secondary to raised pyroglutamate. Her treatment necessitated an emergency Caesarean section, ventilation and haemodiafiltration, despite normal renal function. We provide a reminder of other risk factors associated with the diagnosis.