Acquired 5-oxoproline acidemia successfully treated with N-acetylcysteine

Acquired 5-oxoprolinemia is increasingly recognized as a cause of anion gap metabolic acidosis. It predominantly occurs in chronically ill, malnourished women with impaired renal function and chronic acetaminophen ingestion. Depletion of glutathione and cysteine stores leads to elevated 5-oxoproline levels. N-acetylcysteine, given its effect in repleting glutathione and cysteine stores, has been proposed as a potential treatment for 5-oxoprolinemia, though reports of its successful use are lacking. We present a case of 5-oxoproline metabolic acidosis that persisted despite discontinuation of acetaminophen. However, the acidosis rapidly resolved with N-acetylcysteine administration.