Fatal Pediatric Metformin-Associated Lactic Acidosis: When Severity Goes Unnoticed

Metformin poisoning is rare in the pediatric population but can lead to life-threatening metformin-associated lactic acidosis (MALA) and multiorgan failure, particularly when diagnosis or intervention is delayed. We report the case of a 16-year-old girl who intentionally ingested 34 g of her prescribed metformin following an emotional trigger. She presented to the emergency department one hour after ingestion, hemodynamically stable with unremarkable laboratory findings; however, venous blood gas analysis was not performed at admission. Within 15 hours, she developed severe metabolic acidosis consistent with MALA, acute kidney injury, and progressive hemodynamic instability requiring resuscitative efforts, mechanical ventilation, and vasopressor support. Continuous renal replacement therapy was initiated in the pediatric intensive care unit, but no meaningful clinical improvement was observed. Despite aggressive management, she developed cerebral edema with cerebellar tonsillar herniation and was declared brain dead 46 hours after ingestion. This case reinforces the importance of early recognition and prompt multidisciplinary management of patients at high risk for MALA, given the potential for rapid progression to severe and refractory metabolic acidosis, even in individuals who appear clinically stable at presentation. It also highlights hypoglycemia as a rare but critical manifestation of severe metformin toxicity.