Metabolic acidosis is caused by which of the following?

• A. Renal failure
• B. Diabetic ketoacidosis
• C. Severe diarrhea
• D. Hyperaldosteronism

Answer: (B)

Metabolic acidosis happens when there’s an excess of acid or a loss of bicarbonate, lowering the blood pH. In diabetic ketoacidosis, insulin deficiency triggers rapid lipolysis and ketogenesis, producing ketone bodies like acetoacetate and beta-hydroxybutyrate. These ketones are acids that accumulate in the blood, consuming bicarbonate and increasing the anion gap. The body tries to compensate by hyperventilating to expel CO2, which you often see as rapid, deep breathing. This pattern—high anion gap metabolic acidosis from ketone accumulation—is classic for DKA.

Other conditions can cause metabolic acidosis in different ways. Severe diarrhea wastes bicarbonate from the gut, leading to a non-anion gap acidosis. Renal failure can cause acidosis by the kidneys’ impaired ability to excrete hydrogen ions, but it’s not the ketone-dominant picture seen in DKA. Hyperaldosteronism tends to cause metabolic alkalosis rather than acidosis.