Which ABG description best matches metabolic acidosis due to diarrhea?

Which ABG description best matches metabolic acidosis due to diarrhea?

• A. Low pH with low bicarbonate
• B. High pH with high bicarbonate
• C. Low pH with high bicarbonate
• D. High pH with low bicarbonate

Answer: (A)

When diarrhea occurs, bicarbonate is lost from the intestinal tract, reducing the blood’s buffering capacity. That loss of base shifts the acid-base balance toward acidosis, so the arterial pH drops. Because the problem is metabolic (not primarily a respiratory one), the body compensates by blowing off CO2 via rapid breathing, which lowers the partial pressure of CO2. The net ABG pattern you’d expect is a low pH with a low bicarbonate level, and a compensatory decrease in PaCO2. The other patterns describe alkalosis or a mismatch that doesn’t fit the typical diarrhea-induced change.

When diarrhea occurs, bicarbonate is lost from the intestinal tract, reducing the blood’s buffering capacity. That loss of base shifts the acid-base balance toward acidosis, so the arterial pH drops. Because the problem is metabolic (not primarily a respiratory one), the body compensates by blowing off CO2 via rapid breathing, which lowers the partial pressure of CO2. The net ABG pattern you’d expect is a low pH with a low bicarbonate level, and a compensatory decrease in PaCO2. The other patterns describe alkalosis or a mismatch that doesn’t fit the typical diarrhea-induced change.