Cystatin C is a small plasma protein and an inhibitor of cysteine protease, which is stably produced by all nucleated cells in the human body. Cystatin C can be freely filtered by the glomerulus, and its concentration is negatively correlated with the glomerular filtration rate. It is not affected by factors such as gender, age, diet, inflammation, blood lipids, or liver disease, and can accurately reflect kidney function impairment.
