What happens to glucose concentration if a serum sample is stored at room temperature?

• A. Increases
• B. Decreases
• C. No change
• D. Varies

Answer: (B)

Glucose measured in a serum sample stored at room temperature tends to fall because metabolic activity continues after collection. Erythrocytes and other cells in the blood keep using glucose through glycolysis, producing lactate while consuming glucose. The longer the sample sits at room temperature, the more glucose is consumed, so the concentration decreases over time.

That’s why prompt processing and cooling or using glycolysis inhibitors are recommended to preserve the glucose level. The other possibilities don’t fit because glucose would not increase or stay the same when cellular metabolism is ongoing; it naturally declines with time at room temperature.