Pre- and Post-Serum Calcium Levels in Online Postdilution Hemodiafiltration

Background: Post-dilution hemodiafiltration (OL-HDF) may lead to a negative calcium balance. However, studies have shown that switching from low-flux hemodialysis to OL-HDF does not significantly alter serum calcium levels. We evaluated pre- and post-dialysis serum calcium levels in patients on maintenance OL-HDF. Methods: This cross-sectional, multicenter study aimed to evaluate pre- and post-dialysis calcium levels in patients receiving maintenance post-dilution OL-HDF. Data from all consecutive HDF sessions over the course of one week were included. Results: A total of 79 patients (60.8% male, 44% on conventional, 49.4% on short-daily, and 6.3% on long nocturnal OL-HDF) were included in the study. Pre- and post-dialysis calcium levels from all consecutive sessions are shown in Table 1. All but 4 patients had an increase in calcium levels from pre- to post-OL-HDF. The change in calcium levels was dependent on dialysate calcium concentration (higher with dialysate calcium concentrations equal to or greater than 1.5 mEq/L) and pre-dialysis serum calcium. The frequency and duration of sessions had no effect on the calcium change. Conclusion: Our study shows that OL-HDF significantly alters calcium levels. The change in calcium levels was primarily influenced by the dialysate calcium concentration and pre-dialysis serum calcium, rather than session frequency or duration. This is crucial information for managing patients on long-term hemodialysis. Mean (SD) of calcium levels - Ca levels, md/dL Session 1 Session 2 Session 3 Session 4 Session 5 Session 6 Pre OL-HDF 8.9 (0.8) 9.0 (0.7) 9.1 (0.6) 9.3 (0.6) 9.3 (0.6) 9.4 (0.7) Post OL-HDF 10.2 (0.8) 10.2 (0.7) 10.3 (0.7) 10.3 (0.7) 10.3 (0.7) 10.3 (0.7) Post dialysis maximim value 12.2 11.8 11.9 12.0 11.7 11.8