Urine samples collected for urinalysis can be kept for a maximum of four hours if the temperature is lower in winter. If the maximum time should not exceed two hours in summer, too much time may lead to bacterial growth or exogenous contamination, affecting the test results. For 24-hour urine protein measurement or 24-hour urine sample recording, patients need to receive preservatives in the hospital laboratory department and add a small amount of preservative every 2-4 hours. After adding the preservative, the urine sample can be kept for more than 24 hours, which needs to be determined according to the time and requirements of the test. Currently, frequent urine tests are performed with automated machines; therefore, patients should try not to take samples at home by themselves. Especially in big city hospitals, patients usually have long transportation time and if the urine is outdated it will affect the test results.