Acetate-free biofiltration to remove fibroblast growth factor 23 in hemodialysis patients: a pilot study

Serum levels of 32 kDa-phosphaturic hormone fibroblast growth factor 23 (FGF23) rise early in renal failure in order to keep phosphatemia within the normal range; however, this compensatory mechanism itself contributes to chronic kidney disease-mineral bone disorder. High FGF23 is also associated to left ventricular hypertrophy, vascular calcifications and thus increased cardiovascular risk. The aim of this pilot pre-post study was to evaluate the effects of a single hemodiafiltration session with acetate-free biofiltration (AFB) on FGF23 serum levels.

Nine hemodialysis patients were enrolled; sessions were performed using the Integra^® monitor (Hospal, Bologna, Italy) and a polyacrylonitrile membrane. Peripheral venous blood samples were taken before (pre-HD), at mid- and after treatment (post-HD); dialysate samples were collected by the Quantiscan™ monitoring system. FGF23 was measured by a human FGF-23 ELISA kit. Mid- and post-HD values were corrected for hemoconcentration.

Pre-HD FGF23 levels positively correlated with dialysis vintage (r = 0.7192; p = 0.0443). They were significantly reduced by the hemodialysis session (from 2.38 ± 1.80 to 1.15 ± 1.21 ng/ml, p = 0.0171) with a reduction ratio of 52.55 ± 28.76%. FGF23 was detected in the dialysate samples.

FGF23 underwent a significant reduction during AFB. Such removal was greater than that induced by conventional hemodialysis as reported in the literature (19%-decrease using modified cellulosic membranes). This difference may be attributed to the ability of AFB hemodiafiltration to efficiently remove middle molecules by convection. Whether a better clearance of FGF23 during hemodialysis may result in improved cardiovascular outcomes in the long term needs to be confirmed by randomized controlled trials.