High Anion Gap Metabolic Acidosis and 5-Oxoprolinuria in a Hospital Setting Induced by Acetaminophen, Sepsis, and Malnutrition: A Case Report

High anion gap metabolic acidosis (HAGMA) is a common biochemical abnormality in hospitalized patients, often linked to conditions such as lactic acidosis, renal failure, or drug toxicity. A rare etiology, 5-oxoprolinuria, resulting from acetaminophen use, malnutrition, and sepsis, is increasingly recognized in critically ill patients. We report a 29-year-old male with a history of intellectual disability and normal baseline kidney function who was admitted with acute necrotizing pancreatitis and developed severe metabolic acidosis and acute kidney injury (AKI). Despite extensive management, including continuous renal replacement therapy (CRRT) and hemodialysis, he exhibited persistent HAGMA resistant to standard treatments. Following a prolonged hospital course complicated by various interventions, elevated urine 5-oxoproline levels were identified, leading to the discontinuation of acetaminophen and the initiation of N-acetylcysteine therapy. This case highlights the challenges in diagnosing 5-oxoproline acidosis, particularly in the context of multi-factorial illness involving sepsis and malnutrition. The significant accumulation of 5-oxoproline underscores the metabolic stress associated with reactive oxygen species (ROS) depletion in critically ill patients. The recognition of this condition is crucial, as it indicates underlying metabolic derangements and necessitates prompt therapeutic intervention. Continued awareness and understanding of 5-oxoproline acidosis may improve outcomes in similar patients by guiding appropriate management strategies.