Monitoring 25-OH and 1,25-OH vitamin D levels in hemodialysis patients after starting therapy: Does it make sense?

Background and aims: In hemodialysis patients, monitoring 25-hydroxyvitamin D (25(OH)D) levels is recom-mended. It is however unclear if monitoring 1,25-dihydroxyvitamin D (1,25(OH)2D) levels is interesting.Materials and methods: We repeatedly measured 1,25(OH)2D (DiaSorin Liaison analyser) and 25(OH)D (LCMS/ MS) concentrations in patients newly treated by active or native vitamin D to study the impact of such treatments on serum concentrations.Results: Ten patients were included in the native and 12 in the active vitamin D group. In the native group, a significant increase was observed between the baseline and the last 25(OH)D concentrations available (21.65 [17.39;25.26] versus 33.49[28.60;40.30] ng/mL, p = 0.0059). The baseline and last available 1,25(OH)2D concentrations were not different (12.15[4.25;15.40] versus 11.35[9.72;21.85] pg/mL, p = 0.5566). In the active group, no difference was observed between the baseline and the last 25(OH)D concentrations (51.70 [42.97;63.95] versus 50.89[42.02;64.49] ng/mL, p = 0.5186). The same observation was made for 1,25 (OH)2D concentrations (25.65[17.05;41.85] versus 28.70[23.36;43.73] pg/mL, p = 0.6221). Using a linear mixed model, a significant change over time was only observed in 25(OH)D serum levels for patients treated by with native vitamin D.Conclusion: Measuring 1,25(OH)2D levels in patients newly treated by active vitamin D does not seem useful in monitoring active vitamin D therapy.

Automated summary

This study aimed to investigate the necessity of monitoring 1,25-dihydroxyvitamin D levels in hemodialysis patients. The results showed that there was a significant increase in 25-hydroxyvitamin D levels in patients treated with native vitamin D, but no significant change in 1,25-dihydroxyvitamin D levels. For patients treated with active vitamin D, there were no significant changes in both 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels. Therefore, monitoring 1,25-dihydroxyvitamin D levels in patients newly treated with active vitamin D does not seem useful.