High-Flux Hemodialysis and High-Volume Hemodiafiltration Improve Serum Calcification Propensity

BACKGROUND: Calciprotein particles (CPPs) may play an important role in the calcification process. The calcification propensity of serum (T(50)) is highly predictive of all-cause mortality in chronic kidney disease patients. Whether T(50) is therapeutically improvable, by high-flux hemodialysis (HD) or hemodiafiltration (HDF), has not been studied yet. METHODS: We designed a cross-sectional single center study, and included stable prevalent in-center dialysis patients on HD or HDF. Patients were divided into two groups based on dialysis modality, were on a thrice-weekly schedule, had a dialysis vintage of > 3 months and vascular access providing a blood flow rate > 300 ml/min. Calcification propensity of serum was measured by the time of transformation from primary to secondary CPP (T(50) test), by time-resolved nephelometry. RESULTS: We included 64 patients, mean convective volume was 21.7L (SD 3.3L). In the pooled analysis, T(50) levels increased in both the HD and HDF group with pre- and post-dialysis (mean (SD)) of 244(64) - 301(57) and 253(55) - 304(61) min respectively (P = 0.43(HD vs. HDF)). The mean increase in T(50) was 26.29% for HD and 21.97% for HDF patients (P = 0.61 (HD vs. HDF)). The delta values (Δ) of calcium, phosphate and serum albumin were equal in both groups. Baseline T(50) was negatively correlated with phosphate, and positively correlated with serum magnesium and fetuin-A. The ΔT(50) was mostly influenced by Δ phosphate (r = -0.342; P = 0.002 HD and r = -0.396; P<0.001 HDF) in both groups. CONCLUSIONS: HD and HDF patients present with same baseline T50 calcification propensity values pre-dialysis. Calcification propensity is significantly improved during both HD and HDF sessions without significant differences between both modalities.