(1675) Role of Early Renal Replacement Therapy in Metformin-Induced Vasoplegic Shock: A Case Report

Introduction: Metformin increases lactate production by inhibiting the electron transport chain and subsequently decreases its clearance by NADH-induced inhibition of gluconeogenesis. This Metformin-Associated Lactic Acidosis (MALA) increases Nitric oxide bioreactivity resulting in refractory vasoplegia. It is rare (6 in 100,000), and is usually seen with overdose or renal, hepatic, or cardiac dysfunction.

Description: A 75-year-old male with type 2 diabetes mellitus on metformin and chronic systolic heart failure presented with altered mental status for 1 day. He was afebrile, and hypotensive (86/44 mmHg) with no signs of fluid overload. Labs revealed anion gap metabolic acidosis (pH 7.21, anion gap 42) with lactate >15 mmol/L and bicarbonate 5 mmol/L, creatinine 4.15 mg/dl (baseline 1), blood urea nitrogen (67 mg/dl), glucose (54 mg/dl), and neutrophilic leukocytosis (13.4 K/mcL). Chest X-ray and urinalysis were unremarkable. Refractoriness to IV fluids and broad-spectrum antibiotics for presumed sepsis led to initiation of norepinephrine, vasopressin, and epinephrine drips. Point-of-care ultrasound revealed a non-plethoric, collapsible inferior vena cava and no pericardial effusion, lowering suspicion for cardiogenic and obstructive shock. Given the vasodilatory nature of shock and severe lactic acidosis in the setting of acute renal failure, metformin toxicity was suspected and continuous renal replacement therapy (CRRT) was initiated within 14 hrs of admission. Septic shock was eventually ruled out due to a lack of source, negative blood cultures, and refractoriness to standard therapy. Over 3 days, shock resolved and renal function improved allowing discontinuation of CRRT. Metformin blood levels later resulted at 12 mcg/ml.

Discussion: Metformin-associated vasoplegia being rare and a close mimic of septic shock, is a challenging diagnosis. High mortality rates (~50%) warrant timely management. The majority of current evidence has been derived from case reports and their retrospective analyses. Implications in high-risk populations such as our case and the role of early renal replacement therapy (RRT) have not been exclusively studied. Our case supports early RRT in patients suspected of MALA with vasoplegic shock. Prospective studies/randomized trials are encouraged to assess its significance.