Cystatin C renal function
Cystatin C - Reliable kidney function check for athletes.
This blood test measures the level of cystatin C in the blood. Cystatin C is a small protein that is constantly produced by virtually all cells in the body and filtered out of the blood by the kidneys. The result can be used to assess kidney function.
Why measure cystatin C?
Kidney function is often assessed based on creatinine levels and the eGFR calculated from those levels. However, creatinine levels can be influenced by factors such as muscle mass, age, diet, and physical activity. Cystatin C is much less dependent on muscle mass and can therefore provide additional information about kidney function in certain situations.
Based on the cystatin C level, an estimated glomerular filtration rate (eGFR) can also be calculated. This provides an indication of how well the kidneys are filtering the blood.
When might a cystatin C test be useful?
A cystatin C test, for example, may be useful:
- If you want to learn more about your kidney function;
- when kidney function, as determined by creatinine and eGFR, does not align well with the expected results;
- in cases of relatively high or low muscle mass, which may make creatinine less representative;
- to provide a supplementary assessment of kidney function in addition to creatinine;
- to monitor changes in kidney function over time.
What does an elevated cystatin C level mean?
An elevated cystatin C level may indicate reduced kidney filtration function. Generally speaking, the higher the cystatin C level, the lower the calculated eGFR based on cystatin C.
An abnormal result does not automatically mean you have kidney disease. The result must be evaluated in conjunction with other test results, your medical history, and any symptoms you may have.
Additional testing
For a more comprehensive assessment of kidney function, cystatin C can be combined with, for example, creatinine, eGFR, urea, and a urinalysis, including albumin and creatinine in the urine.
Always discuss abnormal kidney function results with your primary care physician or treating physician.
