Definition A urine protein test is used to detect the presence of protein in a person's urine. Normally, protein is not excreted in urine because the protein molecules are too large to pass through the filtering membranes in the kidneys. If these filtering structures are damaged, protein escapes. The presence of protein in the urine is an important indicator of kidney disease.
Who is a candidate for the test? A test for protein in urine is done when a person is suspected of having:
amyloidosis, a disease in which starch-like substances are deposited in the tissues and organs of the body
Pregnant women are routinely tested for protein in the urine during antenatal visits to the doctor. Protein in the urine during pregnancy can indicate preeclampsia, a serious condition that can cause high blood pressure in the mother.
How is the test performed? A person is asked to supply a urine sample. First, the area around the urethra should be washed to prevent contamination of the sample. Then, the person should:
start urinating in the toilet
catch a sample of urine in the container
finish urinating in the toilet
The container should be covered and delivered to the doctor for testing. The sample is usually the first urine of the day.
Sometimes a 24-hour urine collection is needed for more accurate results. In this process, a person collects all the urine he or she voids during a 24-hour period. In general, this schedule is followed:
Day 1: The patient urinates upon arising as usual and discards that urine. Then, the person collects all urine produced for the next 24 hours in a special container.
Day 2: First thing in the morning, the person collects the morning urine again in the container. Then the person covers the container and refrigerates it until it can be taken to the doctor or assigned laboratory.
Often, urinary protein and several other substances are measured at the same time in a screening test known as urinalysis.
What is involved in preparation for the test? A person should request specific instructions from his or her doctor.
What do the test results mean? Normally, there should be no protein detected in the urine. The presence of protein may indicate:
kidney disease
kidney injury
macroglobulinaemia. This is a serious disease of the plasma causing bleeding tendencies, weight loss, blurred vision, and disease of the lymph nodes.
amyloidosis, a disease in which starch-like substances deposit in the tissues and organs of the body
Author: Stephanie Slon, BA Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
