Metformin-associated lactic acidosis — SCE Endocrinology MCQ

Correct answer: E — Metformin-associated lactic acidosis during hypoxic renal injury

The best answer is “Metformin-associated lactic acidosis during hypoxic renal injury”. Metformin exposure with renal impairment and tissue hypoxia creates a high-risk setting for metformin-associated lactic acidosis; the marked lactate and severe acidemia with absent ketosis fit that syndrome. “Diabetic ketoacidosis despite negligible ketonaemia” is less appropriate because DKA requires clinically important ketonaemia “Hyperosmolar hyperglycaemic state despite modest glucose” is less appropriate because HHS is characterised by profound hyperglycaemia and hyperosmolality rather than this lactate-predominant acidosis “Starvation ketosis as the principal cause of pH 7.12” is less appropriate because starvation may cause ketosis but does not explain the negligible ketones and marked lactataemia “Isolated respiratory alkalosis caused by pneumonia” is less appropriate because respiratory alkalosis raises pH and cannot account for this severe metabolic acidemia

Reference: Metformin 1000 mg tablets: SmPC. https://www.medicines.org.uk/emc/product/13165/smpc