What happens to urine pH if a sample is refrigerated for a prolonged time?

When urine is refrigerated for an extended period, there can be changes in its chemical composition, particularly regarding urea breakdown and bacterial metabolism. As bacteria continue to break down urine components in a cooler environment, they may produce ammonia, leading to an increase in the alkalinity of the urine. As a result, the pH of the urine tends to increase after refrigeration for a prolonged duration. This alteration in pH is primarily due to the shift in the balance of urinary constituents caused by microbial activity.

This is why an increase in urine pH is the correct outcome when a sample is refrigerated for too long. Understanding this helps in maintaining accurate readings and interpretations of urine samples in a clinical setting.