What change occurs in a urine specimen if it is left at room temperature for longer than 1-2 hours?

What change occurs in a urine specimen if it is left at room temperature for longer than 1-2 hours?

• A. Increased ketones
• B. Decreased ketones
• C. No change in ketones
• D. Bacteria growth that alters test results

Answer: (B)

Ketone bodies in urine are not stable when the specimen sits at room temperature. The ketone test commonly used mainly detects acetoacetate, and acetone is volatile. As a sample stands for more than a couple of hours, acetone can evaporate and acetoacetate can be degraded or further metabolized by any residual bacteria. This combination causes the amount of detectable ketone to decline, so the measured ketones appear reduced. Therefore, leaving a urine specimen at room temperature longer than 1–2 hours tends to yield a decreased ketone signal.

Ketone bodies in urine are not stable when the specimen sits at room temperature. The ketone test commonly used mainly detects acetoacetate, and acetone is volatile. As a sample stands for more than a couple of hours, acetone can evaporate and acetoacetate can be degraded or further metabolized by any residual bacteria. This combination causes the amount of detectable ketone to decline, so the measured ketones appear reduced. Therefore, leaving a urine specimen at room temperature longer than 1–2 hours tends to yield a decreased ketone signal.