Abstract
BACKGROUND: Calcidiol insufficiency may accelerate the development of secondary hyperparathyroidism (SHPT). We tested the effect of a substantial increase in calcidiol on mineral metabolism in patients with chronic kidney disease (CKD). METHODS: Ninety-five patients with CKD Stages 3-4, parathyroid hormone (PTH) above 6.8 pmol/L and calcidiol below 75 nmol/L were randomized to receive either cholecalciferol 8000 IU/day or placebo for 12 weeks. The primary endpoint was difference in the mean change in iPTH after 12 weeks. The proportion of participants having a 30% reduction in PTH and the effect on hand grip strength, fatigue and different biochemical variables were also investigated. RESULTS: Baseline calcidiol was 57.5 ± 22 and 56.8 ± 22 nmol/L in the cholecalciferol and placebo groups, respectively. The corresponding concentrations of PTH were 10.9 ± 5 and 13.1 ± 9 pmol/L. Calcidiol increased to 162 ± 49 nmol/L in patients receiving cholecalciferol, and PTH levels remained constant at 10.5 ± 5 pmol/L. In the placebo group, calcidiol remained stable and PTH increased to 15.2 ± 11 pmol/L. The mean change in PTH differed significantly between the two groups (P < 0.01). The proportion of subjects reaching a 30% decrease in PTH did not differ. No effect on grip strength, fatigue, phosphate or fibroblast growth factor 23 was observed. Cholecalciferol treatment resulted in stable calcium concentrations and a substantial increase in calcitriol. CONCLUSION: Treatment with high daily doses of cholecalciferol in patients with CKD Stages 3-4 halts the progression of SHPT and does not cause hypercalcaemia or other side effects.