Effect of calcitriol on serum hepcidin in individuals with chronic kidney disease: a randomized controlled trial

BACKGROUND: Anemia is highly prevalent in chronic kidney disease (CKD). Elevated hepcidin concentrations are an important mediator of disordered iron metabolism, a key mechanism underlying anemia of CKD. Vitamin D was recently shown to reduce serum hepcidin concentrations in healthy individuals. We examined whether treatment with calcitriol reduces serum hepcidin in individuals with CKD. METHODS: A total of 40 participants with stage 3 or 4 CKD (eGFR 15–60 ml/min/1.73m(2)) were randomized to receive either oral calcitriol 0.5 mcg daily or identically-matched placebo for 6 weeks. The primary outcome variable was change in serum hepcidin concentrations. Secondary outcomes variables included the change in iron parameters, calcium, phosphorus, intact parathyroid hormone and hemoglobin concentrations. Study samples were drawn at baseline, 3 days, 1 week, 4 weeks and 6 weeks after randomization. Repeated measures analysis was used to examine differences in outcome variables over time in the two groups. RESULTS: There were no significant differences in the baseline characteristics between the placebo and calcitriol arms. Over 6 weeks of follow-up there were no significant differences in the change in serum hepcidin, iron parameters, or hemoglobin between the two groups. Serum calcium and phosphorus significantly increased and PTH significantly decreased after 6 weeks in calcitriol group whereas these analytes did not change in the placebo group. CONCLUSION: Calcitriol did not reduce serum hepcidin concentrations among individuals with mild to moderate CKD. Future studies are needed to assess if nutritional forms of vitamin D affect hepcidin concentrations in CKD. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01988116. Registered: November 4, 2013. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12882-018-0823-7) contains supplementary material, which is available to authorized users.