What is the normal arterial blood gas bicarbonate (HCO3-) range?

• A. 28-32 mEq/L
• B. 22-26 mEq/L
• C. 18-20 mEq/L
• D. 30-34 mEq/L

Answer: (B)

Bicarbonate on an arterial blood gas reflects the metabolic component of acid-base balance, and the normal arterial HCO3- range is 22 to 26 mEq/L. Values in this range indicate a balanced metabolic status or appropriate metabolic compensation. If HCO3- falls below 22, this points to metabolic acidosis, whereas if it rises above 26, it points to metabolic alkalosis. In ABG interpretation, HCO3- works with pH and PaCO2 to distinguish primary disturbances and the body’s compensatory response. Some labs may report slight variations, but 22–26 mEq/L is the standard reference.