Which condition is a cause of normal anion gap metabolic acidosis?

Which condition is a cause of normal anion gap metabolic acidosis?

• A. Diarrhea
• B. Lactic acidosis
• C. Diabetic ketoacidosis
• D. Uremia

Answer: (C)

Normal anion gap metabolic acidosis happens when bicarbonate is lost or retained with a compensatory rise in chloride, so the measured anion gap stays within the normal range. A classic example is bicarbonate loss through the gastrointestinal tract, such as from diarrhea, where stool bicarbonate is excreted and chloride increases to maintain electroneutrality, producing a hyperchloremic, normal-gap acidosis. The other conditions listed raise the anion gap because they introduce extra unmeasured anions into the blood: lactate in lactic acidosis, ketone bodies in diabetic ketoacidosis, and various retained acids in uremia. Therefore, diarrhea is the cause that results in normal anion gap metabolic acidosis.

Normal anion gap metabolic acidosis happens when bicarbonate is lost or retained with a compensatory rise in chloride, so the measured anion gap stays within the normal range. A classic example is bicarbonate loss through the gastrointestinal tract, such as from diarrhea, where stool bicarbonate is excreted and chloride increases to maintain electroneutrality, producing a hyperchloremic, normal-gap acidosis.

The other conditions listed raise the anion gap because they introduce extra unmeasured anions into the blood: lactate in lactic acidosis, ketone bodies in diabetic ketoacidosis, and various retained acids in uremia. Therefore, diarrhea is the cause that results in normal anion gap metabolic acidosis.