Metformin-Associated Lactic Acidosis Precipitated by an Acute Obstructing Ureteral Stone in a Patient with a Single Functioning Kidney

Abstract

A 35-year-old male with type-2 diabetes mellitus and a history of insulin and metformin (2,000 mg/day) use presented to the emergency department (ED) with generalized weakness. Abdominal computed tomography (CT) performed 3 months prior to presentation showed a severely atrophic right kidney and a few tiny stones in the left kidney, with a serum level of creatinine of 1.14 mg/dL. At the ED, the patient’s blood pressure was 153/89 mmHg. Workup revealed acute kidney injury (creatinine, 11.97 mg/dL), high-anion-gap metabolic acidosis (pH, 6.93), and a blood lactic acid level > 15 mmol/L. Based on the medication history, the patient was diagnosed with metformin-associated lactic acidosis. CT showed a left distal ureteral stone, measuring 6 mm in size, which resulted in hydroureteronephrosis. The patient was initially treated with continuous renal replacement therapy. Subsequently, left percutaneous nephrostomy was performed, which led to the return of the creatinine level to baseline, with complete resolution of lactic acidosis.