Biomarker of Kidney Function
Cystatin C is found in virtually all tissues and is an extracellular cysteine protease inhibitor that belongs to the cystatin superfamily. It is a potent inhibitor of lysosomal proteinases and probably one of the most important extracellular inhibitors of cysteine proteases.
Serum Cystatin C has mainly been used as a biomarker of kidney function, but recently its utility has been broadening to cardiovascular disease. Because of its small size and basic pH, Cystatin C is freely filtered by the glomerulus. It is then reabsorbed by tubular epithelial cells and subsequently metabolized. Urine Cystatin C measurement is also specific for tubular kidney damage.
Beside kidney function Cystatin C has recently also been suggested as being involved in predicting new-onset or deteriorating cardiovascular disease. Several studies have found that increased levels of Cystatin C are associated with the risk of death and several types of cardiovascular disease, such as myocardial infarction, stroke, heart failure, and peripheral arterial disease.
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