Has your doctor suggested you have your cystatin C levels checked? If so, this article will explain what you need to know and what you can expect.
A cystatin C level test can be used as an alternative to a creatinine clearance and a creatinine test to monitor and screen for kidney dysfunction. It is most often performed on patients with suspected or confirmed kidney diseases. This test can be particularly useful when doctors feel a creatinine measurement is not the right test for the patient.
How is This Test Used?
This test is used most often to test kidney function in patients who are very obese, have cirrhosis of the liver, have reduced muscle mass, or for malnourished patients. This test may also be beneficial in the elderly when other parameters are testing as normal, but the doctors are striving to detect possible kidney disease early.
When is This Test Ordered?
This test can be ordered for a number of reasons, but is most often ordered when a doctor suspects the patient has a condition that is affecting his kidneys, particularly a condition that reduces glomerular filtration rate (GFR). It may also be ordered to monitor the kidneys when a patient has a confirmed kidney problem. This test may also be ordered when a doctor is not satisfied with the results of other tests, such as eGFR, creatinine, and creatinine clearance tests.
How is This Test Done?
This test is performed by testing a patient's blood. A phlebotomist or nurse will use a needle and insert it into a vein in the patient's arm. They will draw the blood into a vial and then remove the needle. This blood draw will only take a few minutes.
What Do the Results Mean?
If a cystatin C level test reveals elevated levels of serum cystatin C with a decreased GFR, kidney dysfunction is present. Patients should tell their doctors about their medical conditions and what medications they are taking because some of these may affect the results of this test. Cyclosporine can lead to a decrease in cystatin levels while corticosteroids can lead to an increase in them. Medical conditions, such as malignant conditions and rheumatic diseases, can lead to elevated levels.
Lab Tests Online (2009). Cystatin C Level Blood Test. Retrieved on November 19, 2009 from Website: http://www.labtestsonline.org/understanding/analytes/cystatin_c/test.html