Which statement about bicarbonate (HCO3) is true?

Which statement about bicarbonate (HCO3) is true?

• A. HCO3 has no role in acid-base balance.
• B. Normal range is 28-32 mEq/L.
• C. Normal range is 22-26 mEq/L.
• D. It is the primary determinant of PaCO2.

Answer: (C)

Bicarbonate is the metabolic component of the body's buffering system that helps keep blood pH in balance by pairing with carbonic acid. Its level is tightly regulated by the kidneys, and it provides the base part of the buffering pair that buffers hydrogen ions. The normal range for bicarbonate is 22–26 mEq/L. This is why the statement describing that range is the true one. Bicarbonate does have a role in acid-base balance, so the claim that it has no role isn’t correct. A range of 28–32 mEq/L is outside the normal value, so that option isn’t correct either. The primary determinant of PaCO2 is the lungs (ventilation), not bicarbonate; PaCO2 reflects respiratory status, while HCO3- reflects metabolic status, with the two adjusting in compensation to maintain pH as described by the Henderson-Hasselbalch relationship.

Bicarbonate is the metabolic component of the body's buffering system that helps keep blood pH in balance by pairing with carbonic acid. Its level is tightly regulated by the kidneys, and it provides the base part of the buffering pair that buffers hydrogen ions. The normal range for bicarbonate is 22–26 mEq/L. This is why the statement describing that range is the true one.

Bicarbonate does have a role in acid-base balance, so the claim that it has no role isn’t correct. A range of 28–32 mEq/L is outside the normal value, so that option isn’t correct either. The primary determinant of PaCO2 is the lungs (ventilation), not bicarbonate; PaCO2 reflects respiratory status, while HCO3- reflects metabolic status, with the two adjusting in compensation to maintain pH as described by the Henderson-Hasselbalch relationship.