Summary

Metformin-associated lactic acidosis (MALA) is a rare but life-threatening complication. We report a case of MALA in a man aged 71 years who was treated with continuous renal replacement therapy (CRRT). The patient was brought to the hospital for prolonged and gradual worsening gastrointestinal symptoms. Although he received intravenous treatment, he developed catecholamine-resistant shock, and blood gas analysis revealed lactic acidosis. Bicarbonate and antibiotics for possible sepsis were initiated, but with no clear benefit. Owing to haemodynamic instability with metabolic acidosis, urgent CRRT was given: it was immediately effective in reducing lactate levels; pH values completely normalised within 18 hours, and he was stabilised. MALA sometimes presents with non-specific symptoms, and is important to consider when treating unexplainable metabolic acidosis. In severe cases, CRRT has potential merit, particularly in haemodynamically unstable patients. It is important to be familiar with MALA as a medical emergency, even for emergency physicians.