A Rare Case of Pyroglutamic Acidosis After Cardiac Surgery.

Metabolic acidosis is a common finding following cardiac surgery. Although the differential diagnosis of high-anion-gap metabolic acidosis is well established, less common causes may be overlooked, making the diagnosis challenging. We report the case of a 59-year-old patient who developed high-anion-gap metabolic acidosis after surgical treatment for mediastinitis, caused by the concomitant use of flucloxacillin and paracetamol. This drug interaction disrupts the γ-glutamyl cycle, leading to the accumulation of 5-oxoproline (pyroglutamic acid). Although rare, this interaction may cause a severe and potentially fatal reaction, particularly in patients with renal failure, sepsis, or malnutrition. As such, the possible diagnosis of pyroglutamic acidosis should be kept in mind in these settings, and the use of these medications should be discontinued immediately.