Description

Cystatin C (CysC) is mainly used as a biomarker of kidney function. Cystatin C has a low molecular weight (approximately 13.3 kilodaltons), and it is removed from the bloodstream by glomerular filtration in the kidneys. If kidney function and glomerular filtration rate decline, the blood levels of cystatin C rise. Serum levels of cystatin C are a more precise test of kidney function (as represented by the glomerular filtration rate, GFR) than serum creatinine levels.
This finding is based mainly on cross-sectional studies (on a Single point in time). Longitudinal studies (that follow cystatin C over time) are scarcer; some studies show promising results.

Cystatin C levels are less dependent on age, sex, race and muscle mass compared to creatinine. Cystatin C measurement alone is not been shown to be superior to formula-adjusted estimations of kidney function. As opposed to previous claims, Cystatin C has been found to be influenced by body composition.
It has been suggested that cystatin C might predict the risk of developing chronic kidney disease, thereby signaling a state of
‘preclinical’ kidney dysfunction.