The 24-hour urine protein test checks how much protein is being spilled into the urine, which can help detect disease or other problems. The test is simple and noninvasive.
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.
When higher-than-normal amounts of protein are in the urine, it’s called proteinuria. This is often a sign of kidney damage and disease.
The test doesn’t 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 doesn’t show the cause of the protein loss.
Occasionally, proteinuria isn’t 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 exercise, may also influence the test results.
A 24-hour urine protein test is given if you have symptoms of glomerulonephritis or nephrotic syndrome. Other types of kidney disease or other conditions that affect the kidneys are also sufficient reasons to order the test, including:
The 24-hour urine protein test consists of multiple samples of urine taken over a 24-hour period. It’s different from a protein-to-creatinine ratio test, which uses just one sample of urine. The 24-hour urine protein test may be given as a follow-up to a positive protein-to-creatinine ratio test.
The test doesn’t require anything other than normal urination. There are no risks involved.
The test may be performed at home or in the hospital. Generally, you’ll be given one or more containers to collect and store your urine over a 24-hour period.
Usually, you’ll start in the morning. You won’t save the urine during that first trip to the bathroom. Instead, flush and begin keeping track of time. You will collect the rest of your urine for the next 24 hours.
Store your urine from the 24-hour time period in a cool environment. It can be kept in the refrigerator or on ice in a cooler.
Label the container with your name, date, and time of collection. After 24 hours of urine collection, the samples must be taken to a lab for analysis. If you’re at home, your healthcare provider will tell you how to transport the urine.
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. Tell your doctor about any and all supplements, prescription, and over-the-counter medications that you’re taking.
Other factors can also interfere with test results. These may include how much muscle mass a person has. For example, if a person is very ill, they may not make as much of the muscle protein creatinine. On the other hand, if a person has been bodybuilding and increased their muscle mass, that can also affect the results.
Sometimes vigorous exercise alone can increase the amount of protein a person makes and spills into the urine on a given day.
Test results should be available after a couple of days, depending on the lab schedule. A normal test result shows less than 150 milligrams of protein per day. Test results may vary slightly between laboratories. Ask your doctor about the exact meaning of your test results.
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 test results will help to determine the extent of that damage. The protein amount can also be used to monitor any disease progression or measure your response to therapy.
Proteinuria is associated with many other conditions. These include:
- amyloidosis, an abnormal presence of amyloid proteins in organs and tissues
- bladder cancer tumors
- congestive heart failure
- urinary tract infection
- use of medications that damage the kidneys
- Waldenström’s macroglobulinemia, a rare plasma cell cancer
- glomerulonephritis, inflammation of the blood vessels in the kidneys
- Goodpasture syndrome, a rare autoimmune disease
- heavy metal poisoning
- kidney infection
- multiple myeloma, a cancer of the plasma cells
- lupus, an inflammatory autoimmune disease
- polycystic kidney disease
Your doctor may order more tests to make a diagnosis.