About the Test
Purpose of the test
Urine protein tests are a non-invasive and simple way to catch potential issues early on. A dipstick urine protein test is part of the routine screening when you have a yearly physical.
Because protein in the urine, also called proteinuria, is frequently seen in chronic diseases, such as diabetes and/or hypertension, doctors will look at your levels carefully over time to decide whether additional testing is needed. While there are often no signs and symptoms with early kidney damage, increasing amounts of protein in the urine can be an indicator.
The presence of albumin in the urine (albuminuria) is also a sensitive indicator of kidney disease if you have diabetes and/or hypertension. Therefore, if you have these conditions, it is recommended you are regularly screened for albumin in the urine, as opposed to total urine protein.
Pregnant women with a high pre-screen risk of preeclampsia should also get urine protein tests. Children with high urine protein levels may also be ordered to get a protein-to-creatinine ratio test.
Finally, urine protein tests could be standard if you take medications that may impact kidney function.
What does the test measure?
Urine protein tests detect and/or measure protein being released into the urine. Small amounts of proteins are present in normal urine (less than 150 mg per day), including albumin, small globulins, and glycoprotein (also known as uromucoid). An increase in urine protein levels can be seen in various kidney diseases or other conditions.
There are several kinds of urine protein tests, including:
- A semi-quantitative protein “dipstick” may be performed as part of a urinalysis, generally on a random urine sample. Some commercial dipsticks detect albumin only.
- The quantity of protein in a 24-hour urine sample may be measured and reported as the amount of protein released per 24 hours.
- The amount of protein in a random urine sample may be measured along with urine creatinine and reported as the ratio of urine protein to creatinine (UPCR).
When both a urine creatinine and a random urine protein test are performed, the resulting protein/creatinine ratio approaches the accuracy of the 24-hour urine protein test. Since saving all of the urine for 24 hours can be cumbersome for adults and difficult for infants and children, a random urine protein to creatinine ratio is sometimes substituted for a 24-hour urine protein sample.
When should I get this test?
A dipstick urine protein is measured frequently as a screening test whenever a urinalysis is performed. This may be done as part of a routine physical, a pregnancy workup, when a urinary tract infection is suspected, as part of a hospital admission, or whenever a health care practitioner wants to evaluate kidney function. Repeat testing may also be done when a previous dipstick has been positive for protein to see if the protein persists.
Specifically for monitoring people with possible kidney dysfunction, the National Kidney Foundation has established a five-step plan for chronic kidney disease (CKD) evaluation and referral using random (“spot”) urine albumin-to-creatinine ratio (ACR) to screen for and determine the prognosis of CKD.
A 24-hour urine protein may be ordered as a follow-up test, especially in pregnant women with a high pre-screen risk of preeclampsia, when the dipstick test shows there is a large quantity of protein present in the urine or when protein is shown to be persistently present.
Since the dipstick primarily measures albumin, the health care practitioner may order a 24-hour urine protein test even when there is little protein detected on the dipstick if they suspect proteins other than albumin are being released.
A protein-to-creatinine ratio may be ordered on a random urine sample when a child shows evidence of significant and persistent protein in their urine with the dipstick urine test.
Urine protein testing may also be ordered regularly when you are taking a medication that may potentially affect kidney function, including certain antibiotics, analgesics, COX-2 inhibitors (some non-steroidal anti-inflammatory drugs), and proton pump inhibitors (gastric reflux).
Finding a Urine Protein Test
How can I get a urine protein test?
Your doctor typically orders a urine protein test, either as part of a routine physical or to monitor specific chronic conditions. You’ll usually start with a simple urinalysis lab test. If you have certain conditions that are suspected or being monitored, a physician may order a 24-hour urine protein test or a urine protein and creatinine ratio test.
Can I take the test at home?
There are urine dipstick kits available that allow you to monitor the protein in your urine. This is usually not necessary, though, unless your health care provider is monitoring a known kidney condition.
How much does the test cost?
The cost of urine protein testing depends on which type of test you take, where you take the test, and your insurance coverage. Insurance should cover the cost of testing minus any copayment or deductible you are responsible for.
Speak with your laboratory or your insurance carrier to find out more about the expected costs of urine protein testing.
Taking a Urine Protein Test
A single urine sample is collected in a clean container at any time (random/spot). For a 24-hour urine collection, the process generally begins by discarding the first morning void and then collecting all of the urine for the remaining 24-hour period.
Before the test
There are no special instructions for a urine protein test, and no fasting is needed.
During the test
Urine protein testing involves urinating into a clean container. For a 24-hour urine collection, the process generally begins by discarding the first morning void and then collecting all of the urine for the remaining 24-hour period.
After the test
There are no restrictions or things to be concerned about after doing a urine protein test.
Urine Protein Test Results
Receiving test results
Urine protein test results typically take one to two business days, though a 24-hour test can take a bit longer. Your doctor may share your test results with you, or you may be able to access them through an online patient portal.
Interpreting test results
Normal urine elimination is less than 150 mg total protein per day and less than 30 mg albumin daily. The urine total protein to creatinine ratio or UPCR (mg/mg) is normally less than 0.2 for adults. Elevated urine protein levels may be seen temporarily with conditions such as infections, stress, pregnancy, diet, cold exposure, or heavy exercise.
Persistent protein in the urine suggests possible kidney damage or some other condition that requires additional testing to determine the cause.
If slight to moderate amounts of protein are detected, then a repeat urinalysis and dipstick protein may be performed later to see if there is still protein in the urine or if it has become undetectable.
When there is a large amount of protein in the first sample, repeat testing will be ordered. If increased urine protein levels are observed in follow-up specimens, then a 24-hour urine protein may be ordered along with certain blood tests. The dipstick method primarily measures the protein albumin; if follow-up, repeat urine samples are positive, a 24-hour urine test also may be ordered to obtain more detailed information.
A negative test result means there is no increased amount of protein in the urine at the time of testing.
Protein detected in a random urine sample may be temporary due to an infection, medication, vigorous exercise, pregnancy, diet, cold exposure, or emotional or physical stress. Testing should be repeated after these conditions have been resolved.
Protein in the urine can also be a warning sign of a serious condition and usually warrants further investigation. Typically, three positive urine samples over some time without other significant symptoms will often be followed up with additional tests, including a 24-hour urine test.
Persistent and/or an increased amount of protein in the urine may indicate kidney damage or disease. With kidney disease, the amount of protein present is generally associated with the severity of the damage. Increasing amounts of protein over time indicate increasing damage and decreasing kidney function. The most common cause of protein in the urine is kidney damage resulting from:
- Diabetes – proteinuria is one of the first signs of deteriorating kidney function if you have type 1 and 2 diabetes.
- High blood pressure (hypertension) – proteinuria in someone with high blood pressure is also a first sign of declining kidney function.
Proteinuria may also be seen with many other diseases and conditions. A health care practitioner may order other tests and consider those results to help determine the cause. Some examples of these causes include:
- Urinary tract infection
- Preeclampsia
- Lupus
- Multiple myeloma
- Amyloidosis
- Bladder cancer
- Congestive heart failure
- Drug therapies that are potentially toxic to the kidneys
- Goodpasture syndrome
- Heavy metal poisoning
Your health care practitioner may order additional laboratory tests, such as:
- Comprehensive metabolic panel (CMP) — includes tests such as blood urea nitrogen (BUN), creatinine, albumin and total protein, which help evaluate kidney and liver function
- A full urinalysis — if a condition such as urinary tract infection is also suspected
- Serum and urine protein electrophoresis test — to determine which proteins are being released into the urine and in what quantities. This is especially true if your health care practitioner suspects abnormal monoclonal protein production, such as with multiple myeloma or lymphoma.
If kidney disease or damage is suspected, your health care practitioner may also order imaging scans (ultrasonography or CT scan) to evaluate the appearance of your kidneys or bone marrow biopsy if multiple myeloma is suspected.
It’s always a good idea to talk with your doctor about your test results. Some questions include:
- What are the possible explanations for an elevated urine protein level?
- What are the next steps if my urine protein levels are high?
- Is there anything I can do to help regulate my urine protein level?
- What follow-up testing is needed?
Sources
A.D.A.M. Medical Encyclopedia. Creatinine Urine Test. Updated July 21, 2021. Accessed December 21, 2022. https://medlineplus.gov/ency/article/003610.htm
A.D.A.M. Medical Encyclopedia. Urine Protein Dipstick Test. Updated July 19, 2021. Accessed December 21, 2022. http://www.nlm.nih.gov/medlineplus/ency/article/003580.htm
MedlinePlus: National Library of Medicine. Creatinine Test. Updated December 22, 2020. Accessed December 21, 2022. https://medlineplus.gov/lab-tests/creatinine-test/
MedlinePlus: National Library of Medicine. Microalbumin Creatinine Ratio. Updated September 12, 2022. Accessed December 21, 2022. https://medlineplus.gov/lab-tests/microalbumin-creatinine-ratio/
MedlinePlus: National Library of Medicine. Protein in Urine. Updated May 18, 2022. Accessed December 21, 2022. https://medlineplus.gov/lab-tests/protein-in-urine/
National Institute of Diabetes and Digestive and Kidney Diseases. Your Kidneys and How They Work. Updated June 2018. Accessed December 21, 2022. https://www.niddk.nih.gov/health-information/kidney-disease/kidneys-how-they-work
Rovin BH. Protein in the Urine (Proteinuria) (Beyond the Basics). In: Glassock RJ, ed. UpToDate. Updated August 16, 2021. Accessed December 21, 2022. https://www.uptodate.com/contents/protein-in-the-urine-proteinuria-beyond-the-basics/print
