Why the test is performed
This test is most often performed when kidney disease is suspected. It may be used as a screening test.
Normally, protein is not found in urine when a routine dipstick test is performed. This is because the kidney is supposed to keep large molecules, such as protein, in the blood and only filter out smaller impurities. Even if small amounts of protein do get through, they are normally reabsorbed by the body and used as a source of energy.
Some proteins will appear in the urine if the levels of protein in blood become high, even when the kidney is functioning properly. If the kidney is diseased, protein will appear in the urine even if blood levels are normal.
- For a random urine sample, the normal values are approximately 0 to 8 mg/dL
- For a 24-hour urine collection, the normal value is less than 150 mg per 24 hours
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
Abnormal results may be due to:
- Bladder tumor
- Congestive heart failure
- Diabetic nephropathy
- Goodpasture syndrome
- Heavy metal poisoning
- Lupus erythematosus
- Malignant hypertension
- Multiple myeloma
- Nephrotic syndrome
- Damage to the kidneys from certain drugs (nephrotoxic drugs)
- Polycystic kidney disease
- Urinary tract infection