Clinical value of cystatin C and beta-trace protein in glomerular filtration rate in renal transplant cases with stable renal graft functions: comparison by the 99mTc-DTPA plasma sample method.

Aim: The aim of this study was to investigate the value of cystatin C and beta-trace protein (BTP) levels in determination of the glomerular filtration rate (GFR) by accepting the technetium-99m diethylenetriamine pentaacetic acid (Tc-DTPA) method as the gold standard for GFR measurement in renal transplant patients with stable renal functions and to investigate the value of cystatin C and BTP levels in the determination of GFR in cases with or without renal tubular injury.

Methods: A total of 89 (60 men and 29 women) renal transplant patients aged 19-67 years (mean 38.15 years) with stable graft functions were included in the study. GFR was calculated using three different methods: (a) the Tc-DTPA two plasma sample method; (b) eight different formulas containing cystatin C; and (c) three different formulas containing BTP. In addition, the cases were divided into two groups on the basis of N-acetyl-β-D-glucosaminidase and β2 microglobulin levels showing tubular damage.

Results: GFR values obtained with cystatin C had a better correlation with the gold standard method compared with those obtained with BTP, and the GFR value obtained with cystatin C had the most reliable consistency. We found that cystatin C provided more accurate results in GFR follow-up in renal transplant patients with no tubular injury compared with those with tubular injury.

Conclusion: Cystatin C is a good marker of GFR in renal transplant patients, especially in those with no tubular injury; however, BTP is not as good as cystatin C in that regard.