A fatal autopsy case of metformin-associated lactic acidosis and respiratory failure with proven high plasma metformin concentration

Abstract

Metformin-associated lactic acidosis (MALA) is well known; however, only few studies have performed the blood concentration measurement of MALA and autopsy. We report a fatal autopsy case of MALA and respiratory failure wherein the plasma metformin concentration (PMC) was notably high. A 64-year-old female presented to our department with vomiting and was prescribed metformin for diabetes. She was admitted to the ICU after a diagnosis of MALA, acute kidney injury, and pneumonia. She died despite antibiotic administration, mechanical ventilation, and renal replacement therapy. Her PMC was remarkably elevated to 51.9 mg/L. Autopsy confirmed the presence of focal fusion pneumonia, but any specific cause of lactic acidosis was not found. This is a very rare case wherein both PMC measurement and autopsy were performed. Accumulation of PMC and clinical features are important for diagnosing MALA. Further reports and investigation are required to confirm whether specific pathological findings of MALA exist.