If a routine urine test is done during menstruation and proteinuria is found without red blood cells, this proteinuria is not affected by menstruation. If there are both red blood cells and proteinuria in the routine urine test, it is possible that the proteinuria is caused by menstrual blood dripping into the urine. 3. When you keep the urine specimen, you should not keep the front part of the urine, but only the middle part of the urine, which will not affect the result of the urine test.