[Severe metabolic acidosis as a result of 5-oxoproline in acetaminophen use].

Acetaminophen overdose is a well known cause of liver function disorder and even hepatic failure. Less well known is that even a therapeutic dose of acetaminophen may lead to life-threatening problems. We describe an 84-year-old patient with severe metabolic acidosis and an increased anion gap secondary to 5-oxoproline elevation as a result of acetaminophen use. A systematic approach can help us to determine the cause of a high anion gap metabolic acidosis. In unexplained high anion gap acidosis clinicians should consider the possibility of 5-oxoproline accumulation in patients with risk factors such as acetaminophen use, female sex, malnutrition, infection, diminished liver function or renal failure.