Does online hemodiafiltration lead to reduction in trace elements and vitamins?

Hemodiafiltration (HDF) has been reported to improve nutritional intake, but as it increases convective losses, it could also increase micronutrient loss. We prospectively audited the effect of HDF on vitamin B12, zinc and selenium. Thirty-four patients dialyzing (T/Th/Sa) switched to HDF, and 44 dialyzing (M/W/F) remained on high-flux hemodialysis (HD) and were followed for 12 months. Dialysis adequacy, weight, hemoglobin, and serum albumin did not differ between the groups and did not change over 12 months' follow up. Similarly, vitamin B12 did not differ: HDF, 443 (325-682) ng/mL HD vs. 478 (327-690) ng/mL HDF; 6 months, 513 (351-664) ng/mL vs. 460 (379-647) ng/mL; or 12 months, 444 (317-617) ng/mL vs. 492 (323-644) ng/mL. And no patient had subnormal values. Folate levels, in those not taking supplements, were also stable (start, 6.2 ± 0.7 μg/L HD vs. 7.2 ± 1.0 μg/L HDF; 12 months, 6.5 ± 0.9 μg/L vs. 10.9 ± 2.4 μg/L). Serum zinc was subnormal in 50% prior to switching to HDF, 10.4 ± 0.4 μmol/L, but did not fall with HDF 10.2 ± 0.3 μmol/L; similarly, selenium was low in 49% prior to switching to HDF, 0.77 ± 0.06 μmol/L, but remained stable on HDF, 0.82 ± 0.06 μmol/L. Although HDF adds convective clearance to standard hemodialysis, it does not lead to a reduction in vitamin B12, folate, zinc, or selenium. However, half of this dialysis cohort had low levels of both zinc and selenium.