Bone Mineral Accrual Is Associated With Parathyroid Hormone and 1,25-Dihydroxyvitamin D Levels in Children and Adolescents

Context: Rapid bone accrual and calcium demands during puberty may result in compensatory increases in PTH and 1,25-dihydroxyvitamin D [1,25(OH)(2)D] levels; however, these relations have not been established in longitudinal studies. Objective: To determine whether greater bone accrual velocity is associated with greater PTH and 1,25(OH)(2)D levels in healthy children and adolescents. Design: Prospective cohort study with baseline PTH, 25-hydroxyvitamin D [25(OH)D], and 1,25(OH)(2)D levels and dual-energy x-ray absorptiometry whole-body bone mineral content (BMC) accrual over 12 months. Secondary analyses examined bone biomarkers and tibia quantitative computed tomography midshaft cortical-BMC. Participants: A total of 594 healthy participants, ages 5-21 years, with longitudinal measures in a subset of 145 participants. Main Outcome Measures: PTH and 1,25(OH)(2)D levels. Results: PTH levels were higher during Tanner stages 3 and 4 compared to Tanner 1 (P < .05) in males and females and were inversely and significantly associated with 25(OH)D levels and dietary calcium intake. In multivariable analyses, greater bone accrual [measured directly as change in dual-energy x-ray absorptiometry-BMC (P < .001) or quantitative computed tomography-BMC (P < .05), or indirectly as growth velocity (P < .05) or greater bone-formation biomarker level (P < .01)] was associated with higher PTH levels, independent of 25(OH)D level and dietary calcium intake. Similar associations were observed between these direct and indirect indices of bone accrual and 1,25(OH)(2)D levels. Conclusions: PTH levels rise in midpuberty, in association with multiple measures of bone accrual. This is consistent with compensatory increases in PTH to drive 1,25(OH)(2)D production and calcium absorption during periods of increased calcium demands. Additional studies are needed to address PTH effects on bone modeling and remodeling during growth and development.