title: Cystatin C-based calculation of glomerular filtration rate in kidney transplant recipients.
abstract: Cystatin C (Cys C) has been shown to be an alternative marker of renal function. However, estimation of the glomerular filtration rate (GFR) based on Cys C has received little attention. Recently, several Cys C-based equations were developed in different patient cohorts. To date, the benefit of a Cys C-based GFR calculation in patients after renal transplantation (RTx) remains to be elucidated. We compared the diagnostic accuracy of three Cys C-based formulae (Larsson, Hoek, Filler which used an immunonephelometric method) with the results of the Modification of Diet in Renal Disease (MDRD) formula. GFR was measured by means of technetium-diethylenetriamine pentaacetic acid ((99m)Tc-DTPA) clearance in 108 consecutive patients after RTx. Correlation coefficients of all calculated GFR estimates with the true GFR were high but did not differ significantly from one another (0.83-0.87). The MDRD and Filler equations overestimated GFR significantly, whereas the Larsson equation significantly underestimated GFR. Bias of the Hoek formula was negligible. Precision of the Hoek (8.9 ml/min/1.73 m(2)) and Larsson equations (9.6 ml/min/1.73 m(2)) were significantly better than MDRD equations (11.4 ml/min/1.73 m(2); P< or =0.035 each). Accuracy within 30% of real GFR was 67.0 and 65.1% for the MDRD and Filler formulae, and 77.1% for the Larsson and Hoek formulae, respectively. Accuracy within 50% of true GFR for the Hoek formula (97.2%) was better than for the MDRD equations (85.3%). Cys C-based formulae may provide a better diagnostic performance than creatinine-based equations in GFR calculation after RTx.
authors.affiliation: Department of Internal Medicine I, University of Bonn, Bonn, Germany. dr.poege@nephrologie-bonn.de
authors.forename: U
authors.initials: U
authors.lastname: Pöge
authors.forename: T
authors.initials: T
authors.lastname: Gerhardt
authors.forename: B
authors.initials: B
authors.lastname: Stoffel-Wagner
authors.forename: H
authors.initials: H
authors.lastname: Palmedo
authors.forename: H U
authors.initials: HU
authors.lastname: Klehr
authors.forename: T
authors.initials: T
authors.lastname: Sauerbruch
authors.forename: R P
authors.initials: RP
authors.lastname: Woitas
mesh_terms: D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000502:physiology; D016030:Kidney Transplantation; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D016284:Technetium Tc 99m Pentetate / Q000493:pharmacokinetics
chemical_list: C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D016284:Technetium Tc 99m Pentetate