Paricalcitol versus ergocalciferol for secondary hyperparathyroidism in CKD stages 3 and 4: a randomized controlled trial.

Background: The efficacy of 25-hydroxyvitamin D (25[OH]D) supplementation versus vitamin D receptor activators for the treatment of secondary hyperparathyroidism (SHPT) in patients with chronic kidney disease (CKD) stages 3 or 4 and vitamin D deficiency is unclear.

Study Design: Randomized controlled trial.

Setting & Participants: 80 patients with CKD stages 3 or 4, 25(OH)D level <30 ng/mL, and SHPT in a single medical center.

Intervention: Ergocalciferol, 50,000 units, titrated to achieve serum levels ≥30 ng/mL versus paricalcitol, 1 or 2 μg/d, for 16 weeks.

Outcomes: The occurrence of 2 consecutive parathyroid hormone (PTH) levels decreased by at least 30% from baseline. All analyses were intention to treat.

Results: Baseline characteristics in the 2 groups were similar. 21 patients (53%) on paricalcitol and 7 patients (18%) on ergocalciferol treatment achieved the primary outcome measure (P = 0.002). After 16 weeks, PTH levels did not decrease significantly in patients receiving ergocalciferol, but were decreased significantly in those treated with paricalcitol (mean estimate of between-group difference over 16 weeks of therapy, 43.9 pg/mL; 95% CI, 11.2-76.6; P = 0.009). Serum 25(OH)D levels increased significantly after 16 weeks in only the ergocalciferol group, but not the paricalcitol group (mean estimate of between-group difference over 16 weeks of therapy, 7.08 ng/mL; 95% CI, 4.32-9.85; P < 0.001). Episodes of hyperphosphatemia and hypercalcemia were not significantly different between the 2 groups.

Limitations: Lack of blinding and use of surrogate end points.

Conclusions: Paricalcitol is more effective than ergocalciferol at decreasing PTH levels in patients with CKD stages 3 or 4 with vitamin D deficiency and SHPT.