How must a 24-hour urine specimen be stored?

A 24-hour urine specimen must be stored refrigerated to maintain the integrity of the sample and prevent the degradation of its components. This refrigeration ensures that the metabolic processes within the urine are slowed down, which helps in preserving substances such as hormones, proteins, and electrolytes that may be analyzed. Storing it at room temperature could lead to chemical changes or bacterial growth that might alter the results of laboratory tests.

Using preservatives is sometimes necessary for certain urine tests, but this varies depending on the specific analysis being performed. However, the standard procedure for general 24-hour urine collection requires refrigeration as the primary method of storage. Freezing the specimen is generally not recommended unless specified by the testing laboratory, as it could affect the results by causing some substances to break down or precipitate.