Canadian Society for Medical Laboratory Science (CSMLS) Practice Exam

What occurs when urine is stored at room temperature?

1. Turn alkaline

2. Precipitate crystals

3. Increase in bacterial count

4. All the above

The correct answer is: All the above

When urine is stored at room temperature, a variety of biochemical and microbiological changes occur. First, the pH of the urine can shift, often leading to an alkaline environment. This change can result from the breakdown of urea into ammonia by bacteria, which can thrive in such conditions. Second, as bacteria multiply, they can lead to the precipitation of various salts and crystals. The rise in bacterial count is significant because it contributes to changes in urine composition, which can result in the formation of crystals that may not have been present initially. Lastly, the increase in bacterial count is a direct result of the favorable growth conditions (such as temperature and nutrient availability) in room temperature storage, leading to the potential for urinary tract infections and other complications if the urine is used for diagnostic purposes. Thus, the comprehensive impact of urine storage at room temperature includes the alteration of pH, the potential for crystal precipitation, and a rise in bacterial levels, supporting the idea that all these changes can occur under these conditions.