Which statement best describes why diarrhea leads to metabolic acidosis?

Which statement best describes why diarrhea leads to metabolic acidosis?

• A. Diarrhea causes metabolic alkalosis
• B. Diarrhea causes metabolic acidosis due to bicarbonate loss
• C. Diarrhea causes normal anion gap metabolic acidosis
• D. Diarrhea causes respiratory acidosis

Answer: (B)

Diarrhea leads to metabolic acidosis mainly because stool contains bicarbonate. When large amounts of stool are lost, you shed a significant amount of bicarbonate from the body, reducing the systemic base and tipping the balance toward acidity. Bicarbonate loss diminishes the blood’s buffering capacity, so hydrogen ions accumulate and the pH falls. This form is typically described as a normal anion gap (hyperchloremic) metabolic acidosis because chloride rises to maintain electroneutrality after bicarbonate loss. The respiratory system and kidneys will try to compensate, but the initiating change is the loss of bicarbonate in diarrheal fluid, making bicarbonate loss the best explanation for the acidosis.

Diarrhea leads to metabolic acidosis mainly because stool contains bicarbonate. When large amounts of stool are lost, you shed a significant amount of bicarbonate from the body, reducing the systemic base and tipping the balance toward acidity. Bicarbonate loss diminishes the blood’s buffering capacity, so hydrogen ions accumulate and the pH falls. This form is typically described as a normal anion gap (hyperchloremic) metabolic acidosis because chloride rises to maintain electroneutrality after bicarbonate loss. The respiratory system and kidneys will try to compensate, but the initiating change is the loss of bicarbonate in diarrheal fluid, making bicarbonate loss the best explanation for the acidosis.