Which statement best describes base excess?

Which statement best describes base excess?

• A. Primarily refers to carbonic acid concentration
• B. Positive values reflect metabolic alkalosis.
• C. Created through metabolism of carbohydrates
• D. Negative values represent a respiratory imbalance.

Answer: (B)

Base excess represents the metabolic portion of acid–base status and tells you how much base would need to be added (or removed) to bring the pH to 7.40 if CO2 were at its normal level. A positive base excess means there is an excess of base in the blood, which is the hallmark of metabolic alkalosis. The other statements don’t fit because base excess is not simply a measure of carbonic acid concentration, it isn’t specifically produced by carbohydrate metabolism, and a respiratory imbalance is defined by CO2 changes, with base excess mainly signaling the metabolic contribution (including any compensatory changes).

Base excess represents the metabolic portion of acid–base status and tells you how much base would need to be added (or removed) to bring the pH to 7.40 if CO2 were at its normal level. A positive base excess means there is an excess of base in the blood, which is the hallmark of metabolic alkalosis. The other statements don’t fit because base excess is not simply a measure of carbonic acid concentration, it isn’t specifically produced by carbohydrate metabolism, and a respiratory imbalance is defined by CO2 changes, with base excess mainly signaling the metabolic contribution (including any compensatory changes).