Abstract Introduction Metformin remains a cornerstone in type 2 diabetes management. Although generally safe, metformin-associated lactic acidosis (MALA) is a rare but life-threatening complication. Predisposing factors include renal impairment, sepsis, dehydration, or medications interfering with renal autoregulation. The underlying pathophysiology involves inhibition of mitochondrial oxidative phosphorylation and hepatic gluconeogenesis, leading to impaired lactate clearance and accumulation. Management centers on supportive care, discontinuation of metformin, correction of acidosis, and renal replacement therapy for drug and lactate removal. Case A 67-year-old man with type 2 diabetes, hypertension, and obstructive sleep apnea presented with altered mental status. His medications included metformin and semaglutide, with previously stable glycemic control. Four days before admission, he developed nausea and vomiting. On arrival, vital signs revealed blood pressure 100/35 mm Hg, heart rate 90 bpm, temperature 32.8 °C, and oxygen saturation 78 % on room air. The patient was obtunded and required emergent intubation, vasopressor support, and empiric antibiotics. Foley catheterization yielded an immediate return of 2000 mL urine. Laboratory findings demonstrated leukocytosis, severe azotemia, hyperkalemia, hyperphosphatemia, and high anion-gap metabolic acidosis with elevated lactate. Urine toxicology and ethanol screens were negative. CT imaging showed bibasilar atelectiasis and right perinephric fluid consistent with forniceal rupture, likely secondary to bladder outlet obstruction. CT head and angiography were negative for intracranial pathology. Echocardiography revealed normal systolic function (LVEF 60-65 %).Despite escalating to four vasopressors and bicarbonate infusion, the patient remained in refractory shock. Corticosteroids were added for possible adrenal insufficiency. In the absence of infection and given profound acidosis, metformin toxicity was suspected. Continuous renal replacement therapy (CRRT) was initiated for MALA.. Following CRRT initiation, lactate levels and pH improved, and vasopressor requirements decreased. Serum metformin concentration was 2.4 µg/mL. The patient was extubated within 24 hours and antibiotics were discontinued after negative cultures. Cystoscopy and urodynamic testing later revealed benign prostatic hyperplasia with neurogenic bladder causing post-renal obstruction. He was discharged to a skilled nursing facility after 10 days with complete renal and neurologic recovery. Discussion This case illustrates MALA precipitated by combined pre-renal and post-renal acute kidney injury from bladder outlet obstruction. Early recognition, prompt initiation of CRRT, and avoidance of diagnostic anchoring to sepsis were key to survival in this otherwise fatal presentation. References Visconti, L., Cernaro, V., Ferrara, D., Costantino, G., Aloisi, C., Amico, L., ⋯ Lacquaniti, A. (2016). Metformin-related lactic acidosis: is it a myth or an underestimated reality? Renal Failure, 38(9), 1560-1565. https://doi.org/10.1080/0886022X.2016.1216723 This abstract is funded by: None
Gupta et al. (Fri,) studied this question.