In the backwater of convective dialysis: decreased 25-hydroxyvitamin D levels following the switch to online hemodiafiltration.
OBJECTIVE
Vitamin D deficiency and elevated serum fibroblast growth factor-23 (FGF23) levels are hallmark features and surrogate markers of adverse clinical outcomes in patients with chronic kidney disease (CKD). Convection of molecules over the dialysis membrane during online hemodiafiltration (ol-HDF) increases the removal of larger waste molecules compared with traditional high-flux hemodialysis (HD). The primary aim of this study was to explore the long-term impact of ol-HDF on serum 25(OH)D and FGF23.


METHODS
An observational, prospective, noncomparator study including 35 patients who were switched from HD to ol-HDF. Serum 25(OH)D and FGF23 were measured at baseline (i.e., time of switch to ol-HDF) and at 6, 12, and 24 months.


RESULTS
At follow-up time points, there was a significant reduction in serum 25(OH)D compared with baseline (p<0.0001) whereas FGF23 was unaltered (p>0.05). The decrease in 25(OH)D was more prominent in individuals with higher baseline 25(OH)D levels.


CONCLUSIONS
Ol-HDF may lower systemic 25(OH)D levels by convective mechanisms although the clinical significance remains unknown. Further controlled studies are warranted to replicate these findings in larger patient cohorts.
Fredrik
F
Uhlin
Per
P
Magnusson
Tobias E
TE
Larsson
Anders
A
Fernström
D000328:Adult; D000368:Aged; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood; D017583:Hemodiafiltration; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
C000717427:FGF23 protein, human; D014807:Vitamin D; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; C104450:25-hydroxyvitamin D