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Abstract: TH-PO165

Phosphate Removal During Conventional Hemodialysis Is Continuous and Depends on Pre-Dialysis Serum Levels and Bone Remodeling

Session Information

  • CKD-MBD: Targets and Outcomes
    November 03, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
    Abstract Time: 10:00 AM - 12:00 PM

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical


  • Lima, Carolina Marquez, Universidade de Sao Paulo, Sao Paulo, São Paulo, Brazil
  • Goldenstein, Patricia T., Universidade de Sao Paulo, Sao Paulo, São Paulo, Brazil
  • dos Reis, Luciene, Universidade de Sao Paulo, Sao Paulo, São Paulo, Brazil
  • Jorgetti, Vanda, Universidade de Sao Paulo, Sao Paulo, São Paulo, Brazil
  • Elias, Rosilene M., Universidade de Sao Paulo, Sao Paulo, São Paulo, Brazil
  • Moyses, Rosa M.A., Universidade de Sao Paulo, Sao Paulo, São Paulo, Brazil

Removal of phosphate (P) in conventional hemodialysis (HD) remains a cornerstone for CKD-MBD management. There is a disseminated belief that P removal after the first 90 minutes of HD is irrelevant. In addition, the main determinants of an intradialytic P balance are still a matter of debate.


We measured serum and dialysate P each 30 minduring a HDsession in 10 patients with severe hyperparathyroidism in 3 different periods: before parathyroidectomy (Pre-PTX), during hungry bone syndrome (HBS), and after stabilization of clinical status (Late-PTX). In each period, all patientswere dialyzed 3 times, using a d[Ca] of 1.25, 1.5 or1.75 mmol/L.


P removalwas higher in Pre-PTXthan in HBS and Late-PTX (1098± 313 vs. 744 ±195 and 842 ± 348 mg, respectively, p = 0.04), with no difference among d[Ca]. P removal correlated with pre-dialysis serum P (r = 0.421, p =0.0001) and ultrafiltrationvolume (UF; r=0.259, p =0.014). Percentual serum P reduction in 90 minutes was 52.0%. From this point forward there was no significant change during HD. P removal in 90 minutes was 45.9%. However, despite serum P stabilization, after this point there was a continuous efflux of P, in any study period or d[Ca], of at least 10% every 30 minutes (Figure). GLM revealed that P removal was dependent,in order of importance, on the pre-dialysisserum P, UF and bone remodeling, explaining together 66.8% of P removal.


P removal during conventional HD is higher during the first 90 of therapy, achieving a smaller, but stable flux until the 240 minutes. An intradialytic negative P balance depends not only on the pre-dialysis serum P and UF but also on bone remodeling, which may change the P disposal on the bone surface.

Left: serum P variation during dialysis
Right: P efflux during dialysis


  • Government Support – Non-U.S.