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

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

• A. 12-20 mmol/L
• B. 18-22 mmol/L
• C. 22-26 mmol/L
• D. 28-32 mmol/L

Answer: (C)

Bicarbonate is the main extracellular buffer and a key player in maintaining acid-base balance. In arterial blood, the normal range for HCO3- is about 22 to 26 mmol/L. This mid-20s value supports a stable pH around 7.40 when carbon dioxide is at its normal level. If HCO3- falls below 22, it suggests metabolic acidosis or insufficient buffering; if it rises above 26, it suggests metabolic alkalosis or excessive buffering. The other ranges listed are outside the typical arterial reference interval, so 22-26 mmol/L is the best match.

Bicarbonate is the main extracellular buffer and a key player in maintaining acid-base balance. In arterial blood, the normal range for HCO3- is about 22 to 26 mmol/L. This mid-20s value supports a stable pH around 7.40 when carbon dioxide is at its normal level.

If HCO3- falls below 22, it suggests metabolic acidosis or insufficient buffering; if it rises above 26, it suggests metabolic alkalosis or excessive buffering. The other ranges listed are outside the typical arterial reference interval, so 22-26 mmol/L is the best match.