Advantages of adjusting the initial dose of intravenous calcitriol according to PTH levels

Abstract

Background. To assess the usefulness of starting calcitriol therapy with a dose proportional to the degree of hyperparathyroidism, 141 patients from 28 centers were treated with intravenous calcitriol for 6 months. The aim was to achieve a final PTH between 125 and 250 pg/mL. Patients with serum PTH >250 pg/mL were included in the study and divided into 4 groups according to baseline PTH levels. Methods. The study was completed by 100 patients, a third of which were treated strictly according to the protocol, labeled "compliants"; thus, calcitriol was started according to baseline PTH levels. Two thirds of patients, labeled "noncompliants," showed one or more violation in the dosage regimen. Results. After 2 months of treatment with calcitriol, 59% of the "compliants" and 35% of the "noncompliants" decreased their PTH levels >40% (P = 0.022), 70%, and 49%, respectively after 3 months of treatment. After 3 months of treatment, 67% of the "compliants" reached the target (PTH 125 to 250 pg/mL) in contrast with 23% of the "noncompliants" (P < 0.001). The number of hypercalcemic and hyperphosphatemic episodes was significantly lower in the "compliants" group (P < 0.006). Conclusion. These results demonstrate several advantages when calcitriol therapy is started with a dose proportional to the severity of hyperparathyroidism.