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What Is A Urine Total Protein Test?

Submitted on March 27, 2012

A urine total protein test is conducted to detect excess protein in the urine. This test helps determine an individual's kidney functioning. A urine total protein test is ordered either as a part of a regular physical check-up, or to determine the type of disease or condition affecting the kidney. At times, urine total protein is also a follow-up test to a previous total protein urine test which was positive.

It is important to note that protein is not usually present in urine; therefore, presence of protein in the urine is a sign of abnormality.

Types of Urine Tests

There are two types of urine tests. The urine protein test could either be a random urine sample or it could be a 24-hour total urine protein test, in which the quantity of protein is measured as the amount excreted over the period of 24 hours. However, saving and collecting urine over a 24-hour period can be very inconvenient. Therefore, what can be done is to measure the protein levels in a random urine sample along with a urine creatinine. Creatinine is a muscle metabolism by-product which is constantly excreted into the urine. So, the healthcare provider can test both urine creatinine and urine total protein and arrive at a urine protein to creatinine ratio. This ratio achieves the same accuracy of protein measurement as a 24-hour urine total protein test.

How Does Protein Escape into Urine?

The kidneys are responsible for filtering the blood by excreting waste out of the body in the form of urine. A proper functioning kidney will absorb the filtered proteins and return them to the bloodstream. However, if the kidney is not functioning properly, the filtering process becomes ineffective and residual proteins escape into the urine. Among the first identifiable molecules is albumin, which is a liver-produced protein that forms more than fifty percent of the protein in blood. As the kidney degenerates, the protein content in the urine will continue to increase.

Preparation

While this test requires no specific preparation, it is necessary to inform the health care provider about any drugs consumed in the recent past. The urine sample should be collected in a clean container and shut tight. In case of a 24-hour urine collection, the individual will have to collect all the urine passed in 24 hours. Each sample will have to be refrigerated until the last of the samples is collected. Do ensure that the container is clean and devoid of preservatives of any kind.

Test Results

Besides indicating kidney damage, protein content in the urine could also be a temporary condition caused by medication, stress (both physical and mental), infection, or strenuous physical exercise. If protein is found in urine samples of a pregnant woman, it is a sign of pre-eclampsia. In certain cases, the 24-hour test will indicate protein levels during the day and none at night. This is indicative of a condition called orthostatic proteinuria. Other diseases that could lead to elevated protein levels in urine include diabetes, bladder cancer, hypertension, polycystic kidney disease, kidney infection, urinary tract infection, or heart failure.

It is necessary to note that test results may vary depending on the type of test used to detect protein. The 24-hour test, for instance, will only be accurate if all the urine is collected in 24 hours without fail. As for the creatinine ratio, this is indicative of the protein present in the urine when the sample was collected, and is not a consistent detector of protein levels in the urine. Sometimes, a negative creatinine ratio test could simply mean that at the time of collection there wasn't measurable amounts of protein present in the urine.

Therefore, each test has its pros and cons, and doctors generally take a call on the type of urine test after evaluating the patient's overall health, typical symptoms, and medical history.

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