Initial Dosing of Paricalcitol Based on PTH Levels in Hemodialysis Patients With Secondary Hyperparathyroidism

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Adjustment of the initial dose of paricalcitol in hemodialysis patients with secondary hyperparathyroidism (SHPT) on the basis of severity of SHPT generally is preferred in current practice. Whether the proposed dose, based on the formula baseline intact parathyroid hormone (iPTH [picograms per milliliter]) divided by 80, is the most appropriate has not been assessed adequately. A double-blind randomized trial comparing iPTH/80 dose with the immediately lower iPTH/120 dose was undertaken. Forty-three hemodialysis patients with iPTH levels between 300 and 900 pg/mL (300 and 900 ng/L) were followed up for 12 weeks. The primary outcome was control of iPTH levels within a target range between 150 and 300 pg/mL (150 and 300 ng/L). No difference between the 2 dose groups was noted in time to achieve target iPTH levels of 150 to 300 pg/mL (150 to 300 ng/L). More episodes of excessive decrease in iPTH levels occurred in the iPTH/80 group compared with the iPTH/120 group (P = 0.003). Nine patients in the iPTH/80 group (45%) versus 2 patients in the iPTH/120 group (10%) had iPTH levels less than 150 pg/mL (<150 ng/L) in at least half the measurements performed during the second half of the study (P = 0.034). Increases in calcium levels were greater in the iPTH/80 group at all times during the study (P < 0.05 at weeks 4 and 10). The number of required dose reductions was significantly greater in the iPTH/80 group compared with the iPTH/120 group (P = 0.008). In hemodialysis patients with SHPT, a lower initial dose of iPTH/120 shows efficacy similar to that of the already widely used iPTH/80 scheme in reaching target iPTH levels (150 to 300 pg/mL [150 to 300 ng/L]), with less required dose adjustments, lower increase in calcium levels, and lower cost. In addition, the initial dose of paricalcitol based on the iPTH/80 formula leads significantly more patients to excessive suppression of iPTH (<150 pg/mL [<150 ng/L]) than the iPTH/120 dose.