Cystatin C

Cystatin C is a low molecular weight protein used as a reliable marker of glomerular filtration rate (GFR), offering more accurate estimation than creatinine in many situations since it is less influenced by muscle mass, age, sex, and diet. It is particularly useful in elderly patients, children, individuals with low muscle mass, or those with liver cirrhosis, and may detect mild decreases in GFR earlier than creatinine. Beyond renal assessment, elevated cystatin C levels are associated with increased cardiovascular risk, making it a useful tool for risk stratification. It can also aid in early detection of acute kidney injury in high-risk patients, although its levels can be influenced by thyroid dysfunction and corticosteroid use.