Cystatin C Blood Test

What is the purpose of this test?

The Cystatin C Blood Test is used to evaluate kidney function by measuring levels of cystatin C, a protein produced by the body and filtered by the kidneys. Unlike creatinine-based tests, cystatin C levels are less affected by muscle mass, diet, or age, making it a more reliable indicator of early kidney disease or declining kidney function. This test is especially useful for detecting chronic kidney disease (CKD) in individuals who may not have abnormal creatinine levels, providing a more accurate assessment of how well the kidneys are filtering waste.

It is important to note that while some Cystatin C tests include an estimated glomerular filtration rate (eGFR) calculation, the LabCorp Cystatin C Blood Test does not. If you require a test that includes Cystatin C with eGFR, consider selecting the version offered by the other lab. Your doctor may use this test alone or in combination with other kidney function tests to monitor kidney health, adjust medication dosages, or assess risks for cardiovascular disease.

Who should get this test?

• Individuals at risk for chronic kidney disease (CKD), especially those with diabetes or high blood pressure.
• People with a family history of kidney disease or those who have had previous kidney function concerns.
• Individuals with cardiovascular disease who need an assessment of kidney-related risks.
• Those taking medications that can impact kidney function, such as certain pain relievers, antibiotics, or chemotherapy drugs.
• People with abnormal creatinine test results who need further kidney function testing.
• Older adults or individuals with muscle-wasting conditions, where creatinine-based tests may be less reliable.
• Patients undergoing organ transplants who require kidney function monitoring.

When should I order the Cystatin C Blood Test?

Individuals may consider ordering this test if they have symptoms or risk factors related to kidney disease.

Symptoms to consider:

• Swelling in the hands, feet, or face, indicating fluid retention.
• Fatigue, weakness, or trouble concentrating due to poor waste filtration.
• Frequent urination, especially at night, or reduced urine output.
• Foamy or dark-colored urine, which may indicate protein loss or kidney dysfunction.
• Loss of appetite, nausea, or unexplained weight loss.
• High blood pressure that is difficult to control.

If you have these symptoms or are at risk for kidney disease, the Cystatin C Blood Test can provide important insights into your kidney health and help guide further medical evaluation and treatment.