Comparison of the effects of paricalcitol and calcitriol treatments on osteoprotegerin (OPG) levels in hemodialysis patients

Abstract

Introduction: Osteoprotegerin (OPG), a natural glycoprotein, which plays important roles on regulation and development of vascular calcification, is a key regulator molecule in bone turnover. Studies revealed different results about effects of vitamin D receptor activators (VDRAs) on OPG levels. This study investigated the changes in serum OPG levels and its relationships following VDRAs, paricalcitol and calcitriol treatments, in hemodialysis patients. Materials and methods: Thirty-two hemodialysis patients (14 women, 18 men) were included the study. Demographics and ongoing treatments of patients were recorded. Paricalcitol and calcitriol treatments were initiated randomly. Serum OPG levels, biochemical and hematological tests were measured at baseline and 3th month of the treatment. Results: There was no significant difference between the groups in terms of demographics and basal laboratory tests. No difference was found between paricalcitol and calcitriol groups regarding change from baseline and percent change in biochemical markers and OPG levels. Significant increase in calcium (Ca) levels (p=0.025 vs 0.001), significant decreases in parathyroid hormone (PTH) (p=0.001 vs 0.039) and OPG (p=0.001 vs 0.006) levels were noted at 3th month compared to baseline in paricalcitol and calcitriol group. Conclusion: VDRAs, paricalcitol and calcitriol, both decreased OPG levels in hemodialysis patients. No difference was noted between two therapeutic agents regarding their effects on OPG levels. These findings should be confirmed by further large-scale studies.