What is the proper storage condition for a 24-hour urine specimen?

Storing a 24-hour urine specimen in a refrigerator is crucial for several reasons. First, refrigeration helps to inhibit bacterial growth and the breakdown of substances within the urine that could alter its concentration and composition over the collection period. Urine can undergo chemical changes at room temperature, which may lead to inaccurate test results.

Furthermore, a refrigerator maintains a stable and low temperature that helps preserve the integrity of the various solutes, proteins, and other components in the urine sample, ensuring that the analysis performed after the collection will be reliable. This is especially important for tests that require precise measurements of substances, such as creatinine clearance or protein levels.

In contrast, storing the specimen at room temperature or at body temperature could lead to degradation and misrepresentation of the analytes within the sample. Exposing the sample to light is also detrimental for certain tests, like those measuring bilirubin, which can be sensitive to light degradation. Thus, proper refrigeration is essential for maintaining the quality of a 24-hour urine specimen throughout the collection process.