title: Diagnostic value of cystatin C for diagnosis of early renal damages in type 2 diabetic mellitus patients: The first experience in Iran.
abstract: BACKGROUND
  Diabetic nephropathy (DN) is one of the most important complications of diabetes mellitus. Now-a-days, cystatin C (CysC) is introduced as a new marker for diagnosis of renal damages; however, use of this marker in clinical laboratories is still controversial. The present study was aimed to evaluate the diagnostic value of serum CysC for early detection or monitoring treatment of kidney damages in the Kurdish people with type 2 diabetes mellitus.
  
  
  METHODS
  Glomerular filtration rate (GFR) was estimated by Modification of Diet in Renal Disease formula. Serum CysC and urine microalbumin were also measured in 126 diabetic and healthy subjects. Blood glycated hemoglobin (Hb) also measured in all healthy and diabetic patients. Two independent samples t-test, Mann-Whitney U-test, one-way ANOVA, and Kruskal-Wallis test, as well as Pearson/Spearman correlation coefficient statistical tests were used as appropriate.
  
  
  RESULTS
  Serum CysC was higher (1312.41 ng/ml) in diabetic patients with GFR <60 ml/min than other subjects (993.25 ng/ml) (patients with normal kidney function and healthy subjects). A borderline significant correlation between CysC and estimating GFR (r s = -0.16, P = 0.05) but highly significant with microalbumin (r s = 0.22, P = 0.014) was observed. Serum CysC sensitivity, negative and positive predictive values were 100 and 4%.
  
  
  CONCLUSIONS
  CysC cover variation of GFR and urine microalbumin, but it cannot be used as a surrogating marker of glycated Hb. According to our results, it seems that serum CysC is a useful marker for screening of DN; but it cannot be used for monitoring of treatment in diabetic patients.
authors.affiliation: Department of Biochemistry, College of Science, Kurdistan Science and Research Branch, Islamic Azad University, Sanandaj, Iran.
authors.forename: Mitra
authors.initials: M
authors.lastname: Javanmardi
authors.affiliation: Department of Epidemiology and Biostatistics, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran.
authors.forename: Namam-Ali
authors.initials: NA
authors.lastname: Azadi
authors.affiliation: Department of Biology, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran.
authors.forename: Sabrieh
authors.initials: S
authors.lastname: Amini
authors.affiliation: Cellular and Molecular Research Center, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran ; Department of Clinical Biochemistry, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Abdi
keywords: Cystatin C; diabetic nephropathy; diagnostic value; estimating glomerular filtration rate; hemoglobin A1c; microalbumin