ESPN 51th Annual Meeting

ESPN 2018


 
Beta trace protein based estimation of GFR in children, using rescaling with normal values.
EMIL DEN BAKKER 1 REINOUD GEMKE 1 ISABELLE HUBEEK 1 JOANNA VAN WIJK 1 AREND BOKENKAMP 1

1- VUMC
 
Introduction:

Beta-trace protein (BTP), a low molecular weight protein, has been proposed as a marker for kidney function. Recently for creatinine and cystatin C, two other endogenous markers for kidney function, a new method of deriving eGFR equation using normal values to rescale the markers has been developed. The aim of this study is to apply this approach to BTP in children.

Material and methods:

We retrospectively analyzed serum concentrations of creatinine, cystatin C and BTP measured during inulin clearance test performed on clinical grounds in children. In a subset of 91 subjects with normal GFR the median reference concentration for BTP forming the basis of the eGFRBTP equation was determined and potential confounding factors explored. Performance of the resulting equation was compared to the established creatinine-based FASage and cystatin C-based FAScys equations as well as the BTP-based Benlamri equation in terms of bias, % precision error and P30 and P10 accuracy rates. 

Results:

 417 inulin clearance tests were studied. In the reference subset of 91 subjects with normal GFR median BTP differed significantly between males (0.745 mg/l) and females (0.690 mg/l, p=0.025). Median GFR in the healthy group was 100.0 ml/min/1.73m2. The resulting eGFR equation was eGFRBTP=107.3/BTP/QBTP with QBTP = 0.694 in males and 0.643 in females. Overall, this equation performed comparably to the creatinine-based FASage and the BTP-based Benlamri equations and tended to be less accurate that FAScys (P30: 80.1 vs 84.4%, p=0.104.  At a GFR below 60 ml/min/1.73m2 for eGFRBTP a P30 accuracy of 77.2% was found versus 68.4% compared to FASage.

Conclusions:

 eGFR calculated from BTP standardized for normal values is a promising method for estimating GFR.