[Medical Q&A] Why do the urine routine test results of the same person vary greatly over consecutive days?

Planner: Chinese Medical Association

Reviewer: Ning Yongzhong, Chief Technician, Beijing Chuiyangliu Hospital

There are many possible reasons why the urine routine test results of the same person on consecutive days may vary greatly.

1. Sample collection time is different: As we all know, morning urine has the highest detection rate of formed components, and the composition of morning urine and random urine samples during the day will be different. In addition, according to the "three cups of urine test", that is, the patient is asked to urinate in three urine cups in the front, middle and back sections of a continuous urination, and the results of these three tests will also be different. It can be seen that the test results of the same person taking three samples at the same time of urination will also be different, so the urine test results of the same person taken at different time periods within a day or for several consecutive days will also be different.

2. Changes in diet and water intake: Different food and water intake every day will affect the color, concentration and other components of urine.

3. Fluctuations in physiological state: The body’s physiological state may change at different times, such as the amount of exercise, amount of sweating, etc., which will affect the composition of urine.

4. Sample contamination: If the urine sample is contaminated during collection or storage (such as bacteria from the hands or urethra entering the sample), inaccurate test results may also occur.

5. Improper urine storage: If the urine is not sent for testing in time after collection or the storage conditions are inappropriate (such as the temperature is too high or too low), the test results may also change.

6. Drug influence: Taking certain drugs or supplements may affect urine composition, such as vitamin C may affect urine sugar test results.

7. Changes in physical condition: If the physical condition changes in a short period of time, such as acute infection, fever, dehydration, etc., it may also cause changes in urine routine test results.

8. Other factors: For example, the use of different laboratories or different testing equipment and techniques, the operating level and degree of standardization of different technicians, etc., will affect the consistency of test results.

Therefore, if the urine routine test results of the same person vary greatly over several consecutive days, there is no need to worry too much. It is necessary to analyze the specific situation.