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Cystatin C

Does this test have other names?


What is this test?

This test measures the amount of a protein called cystatin C in your blood.

Your body makes cystatin C constantly, and the protein is found in different fluids, including blood, spinal fluid, and breast milk. When your kidneys are healthy, they filter cystatin C out of the blood so it can be excreted in your urine.

This is a relatively sensitive blood test to look at your kidney health.

Why do I need this test?

You may need this test if your healthcare provider suspects that you have kidney problems.

You may also need this test if you are at an advanced age and your healthcare provider wants to find out your risk for heart complications. But this type of testing is not yet routinely done.

What other tests might I have along with this test?

Your healthcare provider may also order other tests to find out how well your kidneys filter toxins out of your blood. One of these tests is blood creatinine level.

What do my test results mean?

Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you. 

If you have an abnormally high concentration of cystatin C in your blood, it means you may have a kidney condition, such as chronic kidney disease.

Higher levels of cystatin C may also be caused by diabetes, cancer, HIV, hyperthyroidism, or hypothyroidism.

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand 

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore. 

What might affect my test results?

Using steroids can affect your results.

How do I get ready for this test?

You don't need to prepare for this test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.

Online Medical Reviewer: Haldeman-Englert, Chad, MD
Online Medical Reviewer: Walton-Ziegler, Olivia, MS, PA-C
Date Last Reviewed: 9/1/2017
© 2000-2019 The StayWell Company, LLC. 800 Township Line Road, Yardley, PA 19067. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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