title: Cystatin-C and TGF-β levels in patients with diabetic nephropathy.
abstract: OBJECTIVE
  To evaluate renal impairment in type 2 diabetic patients with normoalbuminuria or microalbuminuria by detection of serum cystatin C and serum and urinary TGF-β levels.
  
  
  METHODS
  Cross-sectional study conducted at the Department of Endocrinology in Baskent University School of Medicine. Patients with type 2 diabetes mellitus without known overt diabetic nephropathy were included in the study. Recruited patients were stratified into four groups, matched in terms of age, gender, microalbuminuria level and estimated GFR calculated with MDRD.
  
  
  RESULTS
  78 patients were enrolled. They were categorized into four groups depending on their urinary albumin excretion and estimated glomerular filtration rate. Macrovascular complication was found to be higher in patients with microalbuminuria than in other patients (p<0.01), but there were no differences in terms of other diabetic complications. Serum cystatin C level was significantly higher in normoalbuminuric group one patients, while serum and urinary TGF-β1 levels were higher in microalbuminuric group two patients. The serum level of cystatin C was found to negatively correlate with eGFR in group two patients (r=-0.892, p<0.001). Finally, there was a negative correlation between eGFR and cystatin C in all the patient groups (r=-0.726, p=0.001).
  
  
  CONCLUSIONS
  Although urinary albumin excretion is recommended for the detection of type two diabetic nephropathy, there is a group of patients with decreased eGFR but without increased urinary albumin excretion, in which serum cystatin C level was indicated to be used as an early biomarker of diabetic nephropathy.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Goztepe Training and Research Hospital, Istanbul Medeniyet University, Istanbul, Turkey. Electronic address: mumtaztakir@yahoo.com.
authors.forename: Mumtaz
authors.initials: M
authors.lastname: Takir
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Başkent University Hospital, İstanbul, Turkey.
authors.forename: Aslı Dogruk
authors.initials: AD
authors.lastname: Unal
authors.affiliation: Department of Internal Medicine, Goztepe Training and Research Hospital, Istanbul Medeniyet University, Istanbul, Turkey.
authors.forename: Osman
authors.initials: O
authors.lastname: Kostek
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Başkent University Hospital, İstanbul, Turkey.
authors.forename: Nilufer
authors.initials: N
authors.lastname: Bayraktar
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Başkent University Hospital, İstanbul, Turkey.
authors.forename: Nilgun Guvener
authors.initials: NG
authors.lastname: Demirag
mesh_terms: D000328:Adult; D000368:Aged; D000419:Albuminuria / Q000097:blood; D015415:Biomarkers / Q000097:blood; D003430:Cross-Sectional Studies; D055316:Cystatin C / Q000097:blood*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications*; D003928:Diabetic Nephropathies / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D016212:Transforming Growth Factor beta / Q000097:blood*
chemical_list: D015415:Biomarkers; D055316:Cystatin C; D016212:Transforming Growth Factor beta
keywords: Cistatina C; Cystatin C; Diabetic nephropathy; Microalbuminuria; Nefropatía diabética; Normoalbuminuria; TGF-β1