The 24-hour urine protein test checks the function of the kidneys and detects disease. Urine samples are collected in one or more containers over a period of 24 hours. The containers are kept in a cool environment and then sent to a lab for analysis. Specialists then check the urine for protein. The test is simple and noninvasive.
When higher-than-normal amounts of protein are in the urine, it is called proteinuria. Proteinuria is often a sign of kidney damage and disease.
The test does not show what kinds of protein are in the urine. To determine this, your doctor may also order tests such as a serum and urine protein electrophoresis. The test also does not show the cause of the protein.
Occasionally proteinuria is not a sign of kidney damage. This is especially true for children. Protein levels may be higher during the day than the night. Other factors, such as extreme stress, may also influence the test results.
A 24-hour urine protein test is given if you have symptoms of glomerulonephritis, a type of kidney disease, or other conditions that affect the kidneys, such as:
- uncontrolled diabetes
- high blood pressure
- lupus (an autoimmune disease)
- urinary tract infections (UTIs)
Unlike a protein-to-creatinine ratio test, which is just one sample of urine, the 24-hour urine protein test consists of multiple samples of urine taken over a 24-hour period. The 24-hour urine protein test may be given as a follow-up to a positive protein-to-creatinine ratio test.
The test does not require anything other than normal urination. There are no risks involved.
The test may be performed at home or while you are staying at the hospital. Generally, you will be given one or more containers to collect and store your urine over a 24-hour time period.
Usually, you will start in the morning. You will urinate, flush down the urine, and then begin keeping track of time. You will collect the rest of your urine for the next 24 hours.
Save your urine from the 24-hour time period, storing it in a cool environment. It can be kept cool in the refrigerator or on ice in a cooler.
Label the container with your name, date, and time of completion take your urine to the lab for analysis. If you are at home, your healthcare provider will tell you how to transport the urine.
According to the National Institutes of Health (NIH), a normal test result shows less than 80 milligrams of protein per day. Test results may vary slightly between laboratories. Ask your doctor about the exact meaning of your test results (NIH, 2011).
Protein in the urine may signify kidney damage or disease. Protein levels may also rise temporarily due to factors such as infection, stress, or excess exercise.
If the protein is caused by kidney damage, the amount of protein usually shows how bad the kidney damage is. Very high levels of protein may mean serious kidney damage.
Proteinuria is associated with many other conditions. These include:
- amyloidosis (abnormal presence of amyloid proteins in organs and tissues)
- bladder cancer tumors
- congestive heart failure
- urinary tract infection (UTI)
- use of medications that damage the kidneys
- Waldenström’s macroglobulinemia (a type of white blood cell cancer)
- glomerulonephritis (inflammation of the blood vessels in the kidneys)
- Goodpasture’s syndrome (a rare autoimmune disease)
- heavy metal poisoning
- kidney infection
- multiple myeloma (cancer of the plasma cells)
- lupus (an inflammatory autoimmune disease)
- polycystic kidney disease (cysts on the kidneys)
Your doctor will tell you how to prepare for the test. You may have to stop taking certain medications that can interfere with the test results.
Other factors can also interfere with test results. These may include:
- dehydration (not drinking enough water)
- having a radiology exam with contrast media (dye) within three days of the test
- extreme emotional stress
- urinary tract infection (UTI)
- vigorous exercise
- urine mixed with vaginal secretions, blood, or semen