Severe Metformin Intoxication Resulting in Extreme Lactic Acidosis

The aim of this report is to present a case of massive intentional metformin overdose resulting in extreme metformin-associated lactic acidosis (MALA), acute kidney injury, recurrent cardiac arrest requiring cardiopulmonary resuscitation (CPR), and successful recovery including complete resolution of the transient sensorineural hearing loss following aggressive multidisciplinary management with extracorporeal elimination therapy. A 39-year-old woman intentionally ingested approximately 34 g of metformin (40 tablets of 850 mg) following an acute psychosocial conflict. She rapidly developed profound high-anion-gap metabolic acidosis with a nadir arterial pH of 6.86, peak serum lactate concentration of 41.7 mmol/L, progressive acute kidney injury with anuria, severe hemodynamic instability, and recurrent cardiac arrest requiring repeated CPR. Initial treatment with sodium bicarbonate was insufficient. Intensive care management included mechanical ventilation, intermittent hemodialysis, and continuous veno-venous hemofiltration (CVVH), resulting in gradual correction of metabolic abnormalities, recovery of renal function, resulting in complete clinical stabilization, including restoration of the transient sensorineural hearing loss. In conclusion, massive metformin overdose may lead to life-threatening lactic acidosis, multi-organ dysfunction, and circulatory collapse. This case illustrates that even patients presenting with extreme acidemia and hyperlactatemia can survive when severe MALA is recognized promptly and treated with early extracorporeal elimination combined with comprehensive intensive care.