ObjectiveTo study the changes of serum cystatin C in patients with early renal carcinoma and its clinical significance in renal function evaluation.MethodsRetrospective analysis was performed on 50 cases of non elderly patients with renal clear cell carcinoma who had received surgical treatment, preoperative 99mTc DTPA renal dynamic imaging was employed to measure radionuclide glomerular filtration rate(rGFR), serum cystatin C was used to estimate renal function(eGFR).The patients were grouped according to clinical characteristics such as tumor stage, pathological results, intraoperative findings and urine occult blood to analyze the changes of serum cystatin C in early renal carcinoma and its clinical significance in the evaluation of renal function.ResultsThe serum cystatin C was increased in the patients whose TNM stage was T1bN0M0(P=0.046), tumors was protruded from the renal surface and adhered to the surrounding tissues(P=0.015), and urine occult blood was positive(P=0.000).The eGFR value for evaluation of renal function by serum cystatin C was lower while it had a weak correlation with rGFR(r=0.305)measured by radionuclide renal dynamic imaging.ConclusionThe serum cystatin C was increased in patients with early T1bN0M0 stage of renal clear cell carcinoma or whose tumor was protruded from the renal surface and adhered to the surrounding tissues, or urine occult blood was positive.When the patients had normal renal function, elevation in serum cystatin C may be associated with the aggressive growth of early renal carcinoma.Since cystatin C can be affected by many factors, preoperative renal function must be evaluated in combination with renal dynamic imaging.