Urine Protein Test
What is a urine protein (albumin) test?
A urine protein test is a screening test to look for the presence of proteins in the urine. One of these proteins is called albumin.
Why might this test be ordered?
Proteins are the "building blocks" of the body that also perform other vital functions such as:
- Nourishing tissues.
- Transporting hormones, vitamins and other essential nutrients.
- Keeping the proper amount of fluids circulating through the body.
When the kidneys are healthy, virtually no proteins pass out of the kidneys and into the urine (only waste products circulating in the blood are removed). However, if a person's kidneys become diseased or damaged, they are less able to leave the proteins behind, and some proteins begin to filter through and appear in the urine.
What is the difference between micro-albuminuria and proteinuria?
Albumin is a type of protein found in large amounts in the blood. Because it is a small molecule in size, it is one of the first proteins able to pass through the kidneys into the urine when there are kidney problems. This presence of small amounts of albumin in the urine is the condition called micro-albuminuria. It is important to note that some physiologic conditions may cause micro-albuminuria, such as an episode of exercising. If your urine micro-albumin is elevated, it would be worth repeating after a day or two of no exercising.
As kidney damage progresses and the amount of albumin in the urine increases, the name of the condition changes from micro-albuminuria to macro-albuminuria (macro meaning large) or proteinuria.
What are the signs of micro-albuminuria/proteinuria?
In its early stages, there may be no noticeable signs or symptoms. As kidney function declines and large amounts of proteins are passing into the urine, swelling of the hands, feet, abdomen and face may occur. If albuminuria progresses, it may result in permanent kidney damage. In some patients, it might result in the need for dialysis or a kidney transplant. With or without symptoms, the only way to find out how much protein is passing into the urine is to test it.
Who is at risk for the development of micro-albuminuria/proteinuria?
People with certain chronic diseases – including diabetes, hypertension, obesity and other forms of kidney diseases – are at risk for developing micro-albuminuria/proteinuria. Other at-risk groups include:
- African Americans.
- American Indians.
- Pacific Islander Americans.
- Older people.
- Overweight people.
- People with a family history of kidney disease.
How is the urine protein test used for determining micro-albuminuria/proteinuria?
You will be asked to give a urine sample. Your doctor will decide if the sample can be a random sample provided at your doctor's office or needs to be a sample collected over a certain time frame (such as over four hours, overnight or for 24 hours). In either case, you will be given a container and instructions for properly collecting a urine sample. The sample will then be tested to determine the amounts of protein or albumin in it. Your doctor may also order a blood test to check for other signs of kidney damage (to look for the presence of waste products that would normally be removed from the blood if the kidneys are functioning properly).
Results and Follow-Up
What do the urine protein test results mean?
There’s a range of test results that can indicate normal kidney function. Your healthcare provider will discuss the ranges with you and tell you about your specific results. High values might mean that there’s kidney disease or damage. If your test result shows a high level of protein or albumin, it’s likely that your provider will repeat the test.
If your second test is also high, your healthcare provider may order additional tests to further check your kidney function. When either diabetes or high blood pressure is the cause of the albuminuria, treatment of these problems may reduce albuminuria or its progression to kidney disease. Certain blood pressure medications (angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers) are especially helpful at limiting kidney damage after micro-albuminuria or albuminuria has been found.