What is the glucose concentration in fasting whole blood?

What is the glucose concentration in fasting whole blood?

• A. Less than the concentration in plasma or serum
• B. Greater than the concentration in plasma or serum
• C. Equal to the concentration in plasma or serum
• D. Meaningless because it is not stable

Answer: (A)

Glucose is dissolved mainly in the water of plasma. Whole blood contains cells, which take up space but contribute relatively little water, so the cellular portion lowers the overall water content available for glucose. As a result, the glucose concentration measured in whole blood is lower than in plasma or serum. In practice, plasma glucose is typically about 10% higher than whole-blood glucose. This isn’t meaningless or greater; it reflects how glucose distributes between plasma water and the cellular fraction.

Glucose is dissolved mainly in the water of plasma. Whole blood contains cells, which take up space but contribute relatively little water, so the cellular portion lowers the overall water content available for glucose. As a result, the glucose concentration measured in whole blood is lower than in plasma or serum. In practice, plasma glucose is typically about 10% higher than whole-blood glucose. This isn’t meaningless or greater; it reflects how glucose distributes between plasma water and the cellular fraction.