title: Cystatin C as a marker of renal function in kidney transplant patients.
abstract: BACKGROUND
  Serum creatinine (sCr) is the most commonly used biochemical parameter for gauging kidney function, but, due to its limitations, it is not the ideal marker for glomerular filtration rate (GFR). Cystatin C (sCyC) appears to be an endogenous marker of GFR.
  
  
  OBJECTIVE
  To assess the use of sCyC as a marker of renal function in kidney transplant patients, we compared it with sCr and with creatinine clearance either in a 24-hour urine or calculated using the Cockroft-Gault formula.
  
  
  METHODS
  Among 78 patients (62.8% men, 37.2% women) undergoing kidney transplantation (average age 44.87 +/- 13.37 years) we determined at 2, 5, 7, 15, and 30 days, and 6, 12 and 18 months after kidney transplantation: sCr (using the Jaffé colorimetric method), sCyC (immunonephelometry), creatinine clearance with a 24-hour urine, creatinine clearance using the Cockroft-Gault formula.
  
  
  RESULTS
  During the first 30 days following transplantation, there was a progressive decline in sCr levels. sCyC increased up to the fifth day, coinciding with the highest doses of steroids, and then decreased. At 6, 12, and 18 months, there was a correlation between sCyC and sCr, creatinine clearance in a 24-hour urine or calculated with the Cockroft-Gault formula (R = 0.859; R = -0.713, and R = -0.684, respectively, P < .001.)
  
  
  CONCLUSIONS
  sCyC is an endogenous marker of GFR. Its limitations relate to its being affected by the high doses of steroids in the first days following transplantation. In the 18-month posttransplant period, it correlated with creatinine clearance in a 24-hour urine or calculated by the Cockroft-Gault formula.
authors.affiliation: Nephrology Service, University Clinical Hospital, Valladolid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Mendiluce
authors.forename: J
authors.initials: J
authors.lastname: Bustamante
authors.forename: D
authors.initials: D
authors.lastname: Martin
authors.forename: M
authors.initials: M
authors.lastname: Santos
authors.forename: R
authors.initials: R
authors.lastname: Bustamante
authors.forename: P
authors.initials: P
authors.lastname: Pascual
authors.forename: N S
authors.initials: NS
authors.lastname: Jabary
authors.forename: A
authors.initials: A
authors.lastname: Castañeda
authors.forename: M A F
authors.initials: MA
authors.lastname: Muñoz
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D003404:Creatinine / Q000097:blood / Q000652:urine; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007677:Kidney Function Tests; D016030:Kidney Transplantation / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period
chemical_list: D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D003404:Creatinine