What is the normal range for bicarbonate (HCO3) in the blood?

• A. 34-38 mEq/L
• B. 10-14 mEq/L
• C. 22-26 mEq/L
• D. 28-32 mEq/L

Answer: (C)

Bicarbonate serves as the primary buffering substance in the blood, helping to keep the body’s pH around the normal range by balancing acids produced in metabolism. In a healthy adult, the serum concentration of bicarbonate is typically about 22 to 26 mEq/L. This range reflects normal metabolic buffering that works together with carbon dioxide to maintain stable pH, as described by the relationship between HCO3- and CO2 in acid-base balance. Values higher than this (for example, 28–32 or 34–38 mEq/L) suggest metabolic alkalosis or other issues, while values much lower (like 10–14 mEq/L) indicate metabolic acidosis or depleted buffering capacity. Therefore, 22–26 mEq/L is the best representation of normal bicarbonate levels.