At room temperature, the glucose in whole blood decreases at approximately what rate per hour?

• A. 1-2%
• B. 3-4%
• C. 5-7%
• D. 8-9%

Answer: (C)

Glucose in whole blood keeps being consumed by the cells after the blood is drawn, so its concentration falls unless the sample is processed or preserved. At room temperature, this glycolytic activity happens at a steady pace, and the typical loss is around five to seven percent of the glucose concentration per hour. That’s why clinicians promptly separate plasma or serum, chill the sample, or use glycolysis inhibitors to stabilize glucose for accurate measurement. Rates much lower, like one or two percent, would understate the real loss, while rates approaching eight or nine percent would overestimate it; five to seven percent per hour best fits what’s observed under common room-temperature handling.