What is the normal reference range for bicarbonate (HCO3) in mEq/L?

• A. 22-26 mEq/L
• B. 10-12 mEq/L
• C. 28-32 mEq/L
• D. 34-40 mEq/L

Answer: (A)

Bicarbonate (HCO3-) acts as the main base in the blood’s buffering system, helping to keep the body’s pH in the narrow, healthy range. The normal arterial bicarbonate level is about 22 to 26 mEq/L, a range used clinically as the reference for acid–base status. Values within this range support a balanced acid-base state, while lower values point to metabolic acidosis and higher values indicate metabolic alkalosis or compensation. Among the options, 22–26 mEq/L is the standard normal reference. The other ranges are outside the normal: 10–12 would be far too low, 28–32 is above normal, and 34–40 is clearly elevated.