Vitamin D treatment in hemodialysis patients with low serum levels of parathyroid hormone: which is the best choice?

Abstract Background: This short-term prospective study aimed to assess the effects of treatment with calcidiol (25-hydroxycholecalciferol) or calcitriol in the subset of hemodialysis patients characterized by stable low serum levels of parathyroid hormone (PTH) or affected by hypoparathyroidism after total parathyroidectomy (PTx). Methods: Two groups were created according to baseline serum levels of 25-hydroxyvitamin D (25(OH)D): group A (12 patients): 15 ng/mL; group B (12 patients): 15 ng/mL. They underwent a 6-month treatment with oral calcidiol (group A) or oral calcitriol (group B). Results: Group A showed a statistically significant increase in the serum levels of calcium corrected for serum albumin (cCa), phosphorus (P), total alkaline phosphatases (ALP), PTH and 25(OH)D. Group B showed a statistically significant increase in serum levels of cCa and P. A statistically significant decrease in serum levels of ALP and 25(OH)D was observed. Baseline serum 25(OH)D levels were 12.6 + 3.8 ng/mL in group A and 23.0 + 5.0 ng/mL in group B (p0.0001). After 6 months, they increased to 38.3 + 21.0 ng/mL in group A (p0.01) and decreased to 16.9 + 5.8 ng/mL in group B (p0.01). Conclusions: Our data show that calcidiol is an effective and safe treatment of 25(OH)D deficiency in hemodialysis patients with low serum levels of PTH. It increases PTH and ALP levels, suggesting a shift toward a higher bone turnover. In contrast, calcitriol seems to be less indicated in this subset of patients because it further reduces PTH and ALP levels, thus increasing the risk of adynamic bone disease.