Long-term therapy with paricalcitol for secondary hyperparathyroidism in hemodialysis patients

Purpose: The efficacy of the vitamin D analog paricalcitol has mainly been shown in short-term studies. There are limited data regarding long-term treatment with this agent. This purpose of this study was to determine long-term effects of paricalcitol therapy on parathyroid hormone (PTH) suppression and serum levels of calcium, phosphorus and calcium-phosphorus product (Ca x P). Patients and Methods: Patients who received paricalcitol for ≥ 3 months had the following data collected: demographics, drug dosage, serum PTH, corrected serum calcium concentration, serum phosphorus concentrations and serum Ca x P values. Results: Sixteen patients received paricalcitol for a mean of 18 months. The mean ′ SD dose of paricalcitol was 0.13 ′ 0.12 mcg/kg. The mean ′ SD pre-paricalcitol serum PTH concentration was 705 ′ 423 pg/mL. PTH concentration did not change significantly over the duration of treatment (mean ′ SD: 821 t 480 pg/mL). The number of patients who had at least one corrected serum calcium concentration ≥ 11.5 mg/dL, one serum phosphorus concentration ≥ 6.5 mg/dL, or one Ca x P level > 70 were 75%, 94% and 82%, respectively. Hypercalcemia and elevated Ca x P value resulted in a mean of 17% of doses being withheld during therapy. Conclusion: During the study, PTH was not adequately suppressed by paricalcitol. This was primarily attributed to withholding paricalcitol doses due to elevated serum calcium and Ca x P levels.