To ensure optimal results, it is recommended to ship urine specimens to the laboratory immediately after collection as they start degrading in quality soon after. In case immediate shipping is not possible, here are some guidelines for specimen stability: Urine samples can be stored in the refrigerator for up to 5 days, and for extended periods in the freezer. This applies to all urine tests performed at MosaicDX, except for the Kryptopyrrole test, for which urine must be frozen immediately and received within 24 hours of collection for accurate results.