Calcium-Mediated Parathyroid Hormone Suppression to Assess Progression of Secondary Hyperparathyroidism During Treatment Among Incident Dialysis Patients

Context: Parathyroid gland function is affected adversely by tissue hyperplasia and gland enlargement in hyperparathyroidism. Objective: We examined the effects of 2 treatment strategies on the progression of secondary hyperparathyroidism using measurements of the nonsuppressible component of calcium-regulated PTH secretion as an index of parathyroid mass. Design, Subjects, and Intervention: In this randomized, open-label study, subjects managed with hemodialysis for >3 but 300 pg/mL received cinacalcet and low-dose vitamin D sterols (Cin-D, n = 153) or larger, varying doses of calcitriol, or other vitamin D analogs (Flex-D, n = 151). Study drug doses were adjusted periodically based on PTH and serum total calcium determinations. Main Outcome Measures: The exploratory endpoint was calcium-regulated PTH release, assessed using a standardized PTH suppression test before and after 52 weeks of treatment and 4 weeks aft...