Preliminary findings: 25(OH)D Levels and PTH are indicators of rapid bone accrual in pubertal children

Objective: The objective of this study was to evaluate the role of serum levels of 25(OH)D and PTH on the accumulation of whole body bone mass in a cohort of children. Methods: This was a longitudinal study (1.98 +/- 0.07 y) of sixty-nine children (89% Caucasian, 44% male) 14 enrolled in a calcium supplementation trial. Bone area, bone mineral content (BMC) and density (BMD) of the whole body and radius were assessed using a QDR 2000 (Hologic, Inc) dual energy x-ray absorptiometer. Serum PTH and 25(OH)D were measured using radioimmunoassays. Results: Vitamin D stores were inversely related gain in bone area (p < 0.002), BMC (p < 0.002) BMD (p < 0.027), as well as to PTH levels (p < 0.0001). Compared to those with adequate vitamin D stores (>34 ng/ml), those who had consistently low vitamin D stores (18 ng/ml) had a 8% larger gain in bone area (p < 0.05); 11 % in BMC (p < 0.05) and no differences in gain in BMD; after adjusting for baseline bone measurements, race, gender, season measured, Tanner stage, and calcium intake. Conclusions: High normal PTH with low-normal 25(OH)D stores and moderate to high calcium intake may be beneficial to accruing larger bone size and BMC during puberty.