5-Oxoproline (pyroglutamic) acidosis associated with chronic acetaminophen use.

M etabolic acidosis is a common acid-base disturbance in hospitalized patients. Distinguishing anion gap from non–anion gap metabolic acidosis is a very helpful exercise and enables the clinician to narrow the etiology of the particular acidosis. The use of the anion gap was popularized in an article by Emmett and Narins (1). Over the past few years, the list of conditions that can cause an anion gap metabolic acidosis has expanded. Mehta et al recently developed a “new mnemonic for the 21st century” to add three forms of anion gap metabolic acidosis not included in several popular mnemonics and to delete several obsolete causes (2). The new mnemonic is GOLD MARK, an acronym for glycols (ethylene and propylene), oxoproline (5-oxoproline also called pyroglutamic acid), L-lactate, D-lactate, methanol, aspirin, renal failure, and ketoacidosis. The new additions are D-lactic acidosis, typically seen in patients with short gut syndromes; the accumulation of propylene glycol, a common diluent for intravenous medications; and 5-oxoproline, an increasingly recognized disorder most commonly associated with chronic acetaminophen ingestion. We report a case of 5-oxoproline acidosis in a woman with a history of chronic acetaminophen use.