Background: Different parathyroid hormone (PTH) behavior during hemodialysis with different types of dialysis membranes has been reported. The behavior of intact parathyroid hormone (iPTH) adsorption using different dialysis membranes was assessed in 12 dialysis patients with secondary hyperparathyroidism.
Methods: The study was performed according to a longitudinal scheme comprising three treatment modalities, each lasting 2 weeks, for 6 weeks altogether. The first treatment consisted of standard bicarbonate dialysis with low-flux polysulfone, followed by acetate-free biofiltration with high-flux-polysulfone or with polyacrylonitrile-AN69. In the first week of each period, dialysis was delivered by using a 1.3 m(2) surface area and subsequently, a 1.8 m(2) surface area. Intact parathyroid hormone was assayed on the blood and dialysate samples to calculate iPTH adsorption.
Results: The results showed that polyacrylonitrile-AN69 and high-flux polysulfone induce a significantly larger drop in PTH serum levels as compared with low-flux-polysulfone, particularly in the first half of the dialysis session, while the ionized calcium increase is comparable in all different hemodialysis treatments. The measurement of iPTH in the dialysate showed lower values than those disappearing on the blood side, thus suggesting the presence of an adsorptive mechanism in the different dialysis membranes.
Conclusion: High-flux polysulfone is endowed with a comparable adsorptive capacity per surface unit compared to polyacrylonitrile-AN69, although it seems to show a different behavior, as polyacrylonitrile-AN69 saturates early in the first hour of dialysis corresponding to its maximum adsorption power, while high-flux-polysulfone displays a more lasting adsorptive capacity. Thus, iPTH changes during hemodialysis also depend on dialyzer characteristics and the dialysis membrane adsorption.