ABSTRACT
The renal tubular markers are very important for early diagnosis of renal tubulointerstitial injuries. Urinary excretion of Cystatin C is a sensitive marker of early injury in renal proximal tubule. The particle turbidimetric immunoassay developed in recent years has been used in the autoanalyzer, and may be used in medical laboratories routinely. Urinary cystatin C excretion has early diagnostic value for diabetic nephropathy, hypertensive nephropathy, and drug-induced renal impairments. This tubular marker will be used more frequently for the diagnostic purpose, as the trend of various chronic kidney diseases will be increased in the near future. The current problems to be solved are the standardization of methodology, and the further study according to the guidelines of evidence-based laboratory medicine. In the routine testing, the ratio of a spot urine Cystatin C concentration to creatinine is recommended.