flucloxacillin

High anion gap metabolic acidosis (HAGMA) is a common diagnosis in the emergency department, which requires a systematic work-up in order to identify and treat the underlying cause. We present an unusual case of HAGMA due to 5-oxoproline accumulation caused by prolonged treatment with both acetaminophen (paracetamol) and flucloxacillin. This paper describes the diagnostic work-up of HAGMA and emphasizes on the approach and initial treatment in case the underlying etiology is unclear.