Which condition is a nonanion gap metabolic acidosis cause?

Which condition is a nonanion gap metabolic acidosis cause?

• A. Lactic acidosis
• B. Salicylates
• C. Ethylene glycol
• D. Diarrhea

Answer: (D)

Nonanion gap metabolic acidosis happens when bicarbonate is lost or not adequately reabsorbed, and chloride rises to maintain electroneutrality, so the measured anion gap stays normal. Diarrhea fits this pattern because stool loss removes bicarbonate from the body; as chloride adapts to balance charge, the serum chloride increases and the anion gap remains normal. In contrast, lactic acidosis, salicylate poisoning, and ethylene glycol poisoning introduce unmeasured anions (lactate, glycolate/oxalate, etc.), which raise the anion gap, so they cause ananion gap metabolic acidosis rather than a nonanion gap one.

Nonanion gap metabolic acidosis happens when bicarbonate is lost or not adequately reabsorbed, and chloride rises to maintain electroneutrality, so the measured anion gap stays normal. Diarrhea fits this pattern because stool loss removes bicarbonate from the body; as chloride adapts to balance charge, the serum chloride increases and the anion gap remains normal.

In contrast, lactic acidosis, salicylate poisoning, and ethylene glycol poisoning introduce unmeasured anions (lactate, glycolate/oxalate, etc.), which raise the anion gap, so they cause ananion gap metabolic acidosis rather than a nonanion gap one.