Survival and Vision Restoration Following Severe Metformin-associated Metabolic Acidosis With Transient Blindness: A Case Report and Review of the Literature.

Metformin-associated lactic acidosis (MALA) is a life-threatening condition that may occur as a side effect of biguanides. This condition has a mortality rate of approximately 55 % depending on the severity. Typical symptoms include abdominal pain, nausea, vomiting, and diarrhea, but may also manifest with severe symptoms such as blindness, distributive shock, and renal failure requiring ICU level care. We present the case of a female in her early 70s who arrived at the emergency department with altered mental status and new-onset blindness, later diagnosed with severe acidosis (pH 6.607). She was intubated for hemodynamic instability and continuous renal replacement therapy (CRRT) was started to address her acid-base status. Her metformin concentration was found to be exceptionally high at 34 mcg/ml, significantly surpassing the normal range of 1-2 mcg/ml. Fortunately, the patient survived and was subsequently transferred to the medical floors in stable condition. Physicians should perform medication review and consider "MALA" as a potential etiology of severe acidosis when forming a differential diagnosis.