Understanding a Cystatin C Level Test

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.

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.

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.

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