SAT-521 From Diagnostic Dilemma to Recovery: A Case of Severe Metformin-Associated Lactic Acidosis

Abstract Disclosure: V. Florova: None. R. Aguilar Guerrero: None. A. Lazarev: None. C. Chokapirat: None. Background: Metformin-associated lactic acidosis (MALA) is a rare yet serious complication, typically arising in patients with risk factors like renal impairment, sepsis, or interacting medications that worsen lactic acidosis. Here, we present a case of an elderly diabetic patient on metformin who was admitted with altered mental status (AMS) and a reported history of excessive salicylate intake. Clinical case: A 76-year-old female with a medical history of hypertension, hyperlipidemia, type 2 diabetes mellitus on metformin (850 mg BID), gout, and dementia presented with AMS and labored breathing. Symptoms began in the afternoon of admission and were preceded by 10 days of abdominal pain, decreased appetite, and generalized weakness. Her family reported an episode of non-bloody diarrhea and notified that patient consumed around 2 liters of bismuth subsalicylate total in the last two weeks. Upon arrival, a critically low blood glucose level (17-28 mg/dL) was identified and corrected with intravenous dextrose. In the emergency department, vitals revealed body temperature of 91.4°F, blood pressure 103/54 mmHg, heart rate 111 bpm, and respiratory rate 21 breaths/min on room air. Laboratory findings were significant for acute kidney injury with a creatinine of 11.9 mg/dL (baseline 0.8 mg/dL), blood urea nitrogen 83 mg/dL [7-25], severe metabolic acidosis (bicarbonate <5 mEq/L [21-30], lactic acid 21.2 mmol/L [0.5-2.0], incalculable anion gap), and an arterial blood gas showing pH <7.0 [7.35-7.45], pCO2 36 mmHg [32-45], and pO2 180 mmHg [83-108]. The patient met SIRS criteria due to hypothermia, tachycardia, and leukocytosis (WBC 21.5 x10^3/μL). Additionally, elevated pancreatic enzymes (lipase 117 U/L [11-82], amylase 289 U/L [29-103]) were noted. CT abdomen and pelvis without contrast was performed and showed concerns for ileus or small bowel obstruction. Small bowel obstruction was excluded via the gastrografin challenge. Poison control was consulted, but salicylate toxicity was ruled out after a negative salicylate level, leading to MALA as the primary suspected cause. The patient underwent the emergent hemodialysis, resulting in clinical improvement and normalization of laboratory values. She was discharged home after nine days with documented recovery of kidney function as an outpatient. Conclusion: MALA is a diagnosis of exclusion and should always be considered in diabetic patients with acute dehydration. The interaction between metformin and salicylates is poorly documented but notable. Both activate AMPK via different mechanisms, potentially enhancing insulin sensitivity and reducing liver lipogenesis. Salicylates may further amplify metformin’s effects by preventing AMPKα phosphorylation at Ser-485. Early recognition of MALA and intervention, including hemodialysis, are crucial. Presentation: Saturday, July 12, 2025