Effect of Paricalcitol on Circulating Parathyroid Hormone in X-Linked Hypophosphatemia: A Randomized, Double-Blind, Placebo-Controlled Study

Context: Hyperparathyroidism occurs frequently in X-linked hypophosphatemia (XLH) and may exacerbate phosphaturia, potentially affecting skeletal abnormalities. Objective: The objective of the study was to suppress elevated PTH levels in XLH patients. Design: This was a prospective, randomized, placebo-controlled, double-blind, 1-year trial of paricalcitol, with outcomes measured at entry and 1 year later. Setting: Patients were recruited from the investigators' clinics or referred from throughout the United States. Data were collected in an in-patient hospital research unit. Patients: Subjects with a clinical diagnosis of XLH and hyperparathyroidism were offered participation and were eligible if they were 9 years old or older and not pregnant, and their serum calcium level was less than 10.7 mg/dL, their 25-hydroxyvitamin D level was 20 ng/mL or greater, and their creatinine level was 1.5 mg/dL or less. Intervention: The intervention for this study was the use of paricalcitol or placebo for 1 year. Main...