CST3 and coronary artery disorder: Because cystatin C is freely filtered at the glomerulus at a constant rate and is less affected by sex, age and diet, [25] it is becoming an ideal endogenous marker of GFR.[4]–[6] Recently, cystatin C has been reported to be a predictor for future cardiovascular events including coronary heart disease, lower extremity arterial disease and mortality, independent of renal function.