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Abstract
This project sought to determine relationships among changes in plasma 25(OH)D, plasma IGFI, and BMC in prepubertal females (N = 76; aged 4 to 8 years), over a period of up to 9 years. BMC was measured using DXA. Plasma 25(OH)D and plasma IGF-I were assessed using ELISA and RIA, respectively. Linear mixed modeling that was employed to analyze the proportion of variance each explained on the four bone outcomes. IGF-I was more strongly associated with BMC accrual than 25(OH)D at the total proximal femur (R2 = 0.847 vs. 0.771), radius (R2 = 0.812 vs. 0.759), and lumbar spine (R2 = 0.759 vs. 0.698). At each skeletal site, the rate of BMC accrual was negatively associated with changes in 25(OH)D, but positively associated with changes in IGF-I. These longitudinal data in early adolescent females indicate that both 25(OH)D and IGF-I have a significant impact on bone mineral accrual.