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Kidney Function Tests Information

As the major part of your urinary system, your kidneys are the garbage men of your body. They are responsible for removing the impurities from your blood and converting them into urine. As important they are, kidneys are delicate organs. Any damage done to your kidneys is irreversible, and there are few treatment options for reduced kidney function. If your health-care provider suspects you have kidney problems, she will run a series of kidney function tests.

  1. Kidney Function

    • Your kidneys are reddish, bean-shaped organs located behind the abdomen, near the small of your back. While kidneys also are in charge of releasing hormones that regulate blood pressure, healthy bone development and the production of red blood cells, their main function is filtering blood. Your kidneys filter waste products and excess water from your bloodstream using blood pressure. Then they mix the waste products and excess water into urine, which is stored in the bladder before being excreted from the body.

    Blood Urea Nitrogen Test

    • The blood urea nitrogen test (BUN) is done to determine the amount of urea nitrogen in the blood. Urea nitrogen is the byproduct of protein breakdown. Urea is generally filtered out by the kidneys and used to make urine. If there is an elevated amount of urea in your blood, it can mean that your kidney's filtration system is malfunctioning. The test is done by drawing blood and having it analyzed by a lab. Before having this test done, notify your health-care provider of all the medications you are taking, especially drugs like Streptomycin, Allopurinol and Colistin, as these drugs can skew the BUN test results. Propranolol and high doses of aspirin can also give false BUN test results. Your health-care provider might ask you to stop taking these drugs for a period or choose another kidney function test.

    Creatinine Blood Test

    • A creatinine blood test (also known as a serum creatinine test) measures the blood's percentage of creatinine, a product of the breakdown of creatine. The test is performed through a simple blood test and lab analysis. You should always disclose any drugs that you are taking to your health-care provider. If you are taking Bactrim, Cimetidine or any heavy-metal chemotherapy drugs, he may tell you to stop taking them or choose to use another test for your kidney function diagnosis. These types of drugs can skew the results of a creatinine test.

    Urine Creatinine Test

    • The urine creatinine test measures the amount of creatinine present in the urine. Creatinine is a byproduct of the breakdown of creatine. There is no special preparation for the test, but if you are taking Cephalosporins, Cimetidine or Cisplatin, your health-care provider may request that you discontinue the medication so it doesn't distort the test results. On the first day of this test, you begin by urinating in the toilet. The rest of the urine you release for the next 24 hours is collected in a container. You will continue to do that through your first urination on day two.

    Creatinine Clearance Test

    • A creatinine clearance test compares the amount of creatinine found in the blood with that found in the urine. It is a combination of the creatinine blood test and the urine creatinine test. It requires a sample of all the urine released during a 24-hour period and a sample of blood taken at the end of that 24-hour period. The creatinine clearance rate is measuring the glomerular filtration rate of the kidneys. The creatinine clearance test on infants requires that you place a collection bag over a boy's penis or girl's labia and attach it to his or her skin with adhesive before diapering the baby as usual. Each time the infant urinates in the bag, it should be drained into a container and replaced.

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