How is the cause of proteinuria diagnosed?
Further tests may be necessary after protein has been detected by a simple ‘dipstick’ test on a small urine sample. This dipstick test is very sensitive, but cannot measure exactly how much protein is in the urine. To get an exact measurement, some urine needs to go to the laboratory. This can be done with a single small urine specimen, in which the laboratory measures the levels of protein and creatinine (‘protein-creatinine ratio’ or PCR for short). A collection of a whole days urine output (24 hour collection) into a container was the standard method for measuring protein in the urine for many years, but is now being replaced by the far more convenient PCR test. A PCR of less than 2 mg/mmol is normal. Levels of up to 50 usually do not indicate serious kidney disease, so long as the kidney function (measured by blood creatinine level or eGFR) is normal. However, a PCR of 20-50 in someone who has diabetes will require further action, especially to reduce the blood pressure, improve th
