Serum cystatin C is a more sensitive and more accurate marker of glomerular filtration rate than enzymatic measurements of creatinine in renal transplantation.
OBJECTIVE
Serum creatinine has several drawbacks as marker of glomerular filtration rate (GFR), and therefore serum cystatin C has been proposed as a more optimal GFR marker. Previous reports have suggested benefits of serum cystatin C measurements in patients with renal transplants. The purpose of the present study was to evaluate the diagnostic accuracy of cystatin C measurements compared with enzymatic creatinine measurements as serum markers of GFR (established from plasma clearance of iohexol) in a large cohort of stable renal transplant recipients and in the early postoperative phase.


METHODS
Renal transplant patients (n = 125) with stable graft function were evaluated from reciprocals of serum creatinine and cystatin C compared with iohexol clearance. Fourteen patients were examined immediately after the onset of renal function. Cystatin C was measured by a particle-enhanced turbidimetric method and creatinine by an enzymatic method.


RESULTS
In stable renal transplant recipients, serum cystatin C showed a significantly (p = 0.033) closer correlation (r = 0.89 or 79% co-variance) with iohexol clearance than did serum creatinine (r = 0.81 or 66% co-variance). Using the chi(2) test and a cut-off at 60 ml/min/1.73 m(2), serum cystatin C levels demonstrated significantly higher sensitivity for early GFR impairment (p = 0.0045) compared with serum creatinine measurements. On the first day after transplantation, serum cystatin C fell more rapidly than serum creatinine.


CONCLUSIONS
Serum cystatin C levels correlate significantly closer to accurate measurements of GFR and are significantly more sensitive to detect early GFR impairment than enzymatic measurements of creatinine in serum.
Christensson
Anders
A
Department of Nephrology and Transplantation, Malmö University Hospital, Malmö, Sweden. Anders.Christensson@medforsk.mas.lu.se
Ekberg
Jana
J
Grubb
Anders
A
Ekberg
Henrik
H
Lindström
Veronica
V
Lilja
Hans
H
D000328:Adult; D000368:Aged; D000581:Amidohydrolases / Q000378:metabolism; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood / Q000378:metabolism* / Q000652:urine; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007472:Iohexol / Q000378:metabolism; D007676:Kidney Failure, Chronic / Q000628:therapy; D007678:Kidney Glomerulus / Q000201:enzymology*; D016030:Kidney Transplantation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity
D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D007472:Iohexol; D003404:Creatinine; D000581:Amidohydrolases; C019946:creatininase