A controlled trial of the early treatment of secondary hyperparathyroidismwith calcitriol in hemodialysis patients

<(Background)under bar>: Calcitriol is widely used in conjunction with phos phorus-binders containing calcium to treat secondary hyperparathyroidism in dialysis patients. Its efficacy in patients with severe hyperparathyroidis m is diminished, in part, due to glandular hyperplasia associated with decr eased calcitriol and calcium receptors. <(Subjects and methods)under bar>: We, therefore, developed a prospective, randomized trial comparing i.v. cal citriol plus calcium carbonate (CaCO3) compared to CaCO3 alone (control) in patients with mild to moderate hyperparathyroidism who were within the fir st year of initiating hemodialysis. Patients underwent calcium (Ca) suppres sion/stimulation testing at baseline and after six and twelve months of tre atment to indirectly assess parathyroid gland hyperplasia. <(Results)under bar>: In the calcitriol group, the amino-terminal parathyroid hormone (N-PT H) decreased significantly from a baseline value of 70 +/- 12 pg/ml at mont h zero to 22 +/- 7 and 19 +/- 6 pg/ml at months 6 and 12, respectively (the conversion factor of amino-terminal PTH to intact PTH is 6, i.e., 10 pg/ml N-PTH equals 60 pg/ml intact PTH). In contrast, the N-PTH levels in the Ca CO3 alone group did not change. The change in nadir N-PTH levels at month 1 2 compared to month zero decreased by 14 +/- 7% in the calcitriol group but increased by 96 +/- 59% in the control group (p < 0.05). In addition, the increment in N-PTH levels during hypocalcemic stimulation decreased by 68 /- 6% at month 12 compared to month zero but increased by 61 +/- 42% in the control group. Although total calcium and phosphorus levels were not diffe rent between the two groups, ionized calcium values were higher in the calc itriol group. The incidence of hypercalcemia was the same in both groups an d the episodes were asymptomatic. <(Conclusion)under bar>: Pulse calcitriol therapy is effective in preventing progression of secondary hyperparathyro idism in hemodialysis patients with mild to moderate disease. Based on Ca s uppression/stimulation tests, calcitriol was more successful in preventing gland growth than CaCO3 alone. Further studies are needed to determine if t he strategy of early treatment of mild to moderate hyperparathyroidism by p ulse calcitriol is safe and effective in hemodialysis in patients.