title: Comparison of Cystatin C and β-Trace Protein Versus 99mTc-DTPA Plasma Sampling in Determining Glomerular Filtration Rate in Chronic Renal Disease.
abstract: Glomerular filtration rate (GFR) is the best indicator of renal function. The gold standard for GFR measurement is inulin clearance. However, its measurement is inconvenient, time-consuming, and costly. Thus, in both scientific studies and routine clinical practice nuclear medicine methods ((99m)Tc-diethylenetriaminepentaacetic acid [(99m)Tc-DTPA] and (51)Cr-ethylenediaminetetraacetic acid [(51)Cr-EDTA]) are preferred, and they correlate strongly with inulin clearance. In addition, cystatin C and β-trace protein have also recently been used for this purpose. In the literature, however, data are limited about the clinical value of cystatin C and β-trace protein in GFR measurement in chronic renal disease (CRD), and the results have been inconclusive. In this study, we aimed to determine the efficiency of cystatin C and β-trace protein in the determination of GFR in CRD patients.
  
  
  METHODS
  Eighty-four patients with CRD were included in the study (59 men and 25 women; age range, 21-88 y; mean age, 61 y). GFR was calculated using the gold-standard (99m)Tc-DTPA 2-sample plasma sampling method (TPSM) and 2 alternative methods: a formula using cystatin C and a formula using β-trace protein. The correlation between TPSM and the cystatin C and β-trace protein methods was assessed, and Bland-Altman analysis was used to graph scatterplots of the differences at a confidence interval of 95% (mean difference ± 1.96 SDs).
  
  
  RESULTS
  GFRs calculated using both alternative methods correlated strongly with those calculated using the gold standard. However, the correlation was stronger for the cystatin C method than for the β-trace protein method, and neither method produced reliably consistent GFRs.
  
  
  CONCLUSIONS
  This study demonstrated that cystatin C and β-trace protein do not reflect GFR with sufficient accuracy.
authors.affiliation: Department of Nuclear Medicine, School of Medicine, Akdeniz University, Antalya, Turkey afunda@akdeniz.edu.tr.
authors.forename: Funda
authors.initials: F
authors.lastname: Aydin
authors.affiliation: Department of Nuclear Medicine, School of Medicine, Akdeniz University, Antalya, Turkey.
authors.forename: Evrim Surer
authors.initials: ES
authors.lastname: Budak
authors.affiliation: Department of Nuclear Medicine, School of Medicine, Akdeniz University, Antalya, Turkey.
authors.forename: Serkan
authors.initials: S
authors.lastname: Demirelli
authors.affiliation: Department of Nuclear Medicine, School of Medicine, Afyon Kocatepe University, Afyonkarahisar, Turkey.
authors.forename: Ali Ozan
authors.initials: AO
authors.lastname: Oner
authors.affiliation: Department of Biostatistics, School of Medicine, Akdeniz University, Antalya, Turkey.
authors.forename: Selen
authors.initials: S
authors.lastname: Korkmaz
authors.affiliation: Department of Internal Medicine, Division of Nephrology, School of Medicine, Akdeniz University, Antalya, Turkey; and.
authors.forename: Gultekin
authors.initials: G
authors.lastname: Suleymanlar
authors.affiliation: Department of Biochemistry, School of Medicine, Akdeniz University, Antalya, Turkey.
authors.forename: Halide
authors.initials: H
authors.lastname: Akbas
authors.affiliation: Department of Biochemistry, School of Medicine, Akdeniz University, Antalya, Turkey.
authors.forename: Fatih
authors.initials: F
authors.lastname: Davran
authors.affiliation: Department of Nuclear Medicine, School of Medicine, Akdeniz University, Antalya, Turkey.
authors.forename: Firat
authors.initials: F
authors.lastname: Gungor
mesh_terms: D000328:Adult; D000368:Aged; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D019746:Intramolecular Oxidoreductases / Q000097:blood*; D054834:Lipocalins / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011865:Radioisotope Dilution Technique; D019275:Radiopharmaceuticals / Q000097:blood; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000175:diagnosis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016284:Technetium Tc 99m Pentetate / Q000097:blood*
chemical_list: D055316:Cystatin C; D054834:Lipocalins; D019275:Radiopharmaceuticals; D019746:Intramolecular Oxidoreductases; C022466:prostaglandin R2 D-isomerase; D016284:Technetium Tc 99m Pentetate
keywords: beta trace protein; cystatin C; glomerular filtration rate