Associations between adiposity, hormones, and gains in height, whole-body height-adjusted bone size, and size-adjusted bone mineral content in 8- to 11-year-old children

Summary We examined fat-independent associations of hormones with height and whole-body bone size and mineral content in 633 school children. IGF-1 and osteocalcin predict growth in height, while fat, osteocalcin, and in girls also, IGF-1 predict growth in bone size. Leptin and ghrelin are inversely associated with bone size in girls. Introduction Obesity causes larger bone size and bone mass, but the role of hormones in this up-regulation of bone in obesity is not well elucidated. We examined longitudinal associations between baseline body fat mass (FM), and fat-independent fasting levels of ghrelin, adiponectin, leptin, insulin, insulin-like growth factor-I (IGF-1), osteocalcin, and intact parathyroid hormone, and subsequent changes in height and in whole-body height-adjusted bone area “BA height ” and size-adjusted bone mineral content “BMC size ” in 8- to 11-year-olds. Methods Analyses were carried out separately for boys ( n = 325) and girls ( n = 308) including data from baseline, 3 and 6 months from OPUS School Meal Study. Results In both sexes: gain in BA height was positively associated with baseline FM (≥2.05 cm 2 /kg, both p ≤ 0.003). Furthermore, gain in height was positively associated with baseline IGF-1 (≥0.02 cm/ng/ml, p = 0.001) and osteocalcin (≥0.13 cm/ng/ml, p ≤ 0.009); and gain in BA height was positively associated with baseline osteocalcin (≥0.35 cm 2 /ng/ml, p ≤ 0.019). In girls only, gain in BA height was also positively associated with baseline IGF-1 (0.06 cm 2 /ng/ml, p = 0.017) and inversely associated with both baseline ghrelin (−0.01 cm 2 /pg/ml, p = 0.001) and leptin (−1.21 cm 2 /μg/ml, p = 0.005). In boys, gain in BMC size was positively associated with osteocalcin (0.18 g/ng/ml, p = 0.030). Conclusions This large longitudinal study suggests that in 8- to 11-year-old children, IGF-1 and osteocalcin predict growth in height, while FM, osteocalcin, and in girls also, IGF-1 predict growth in BA height . Fat-independent inverse associations of leptin and ghrelin with BA height in girls’ are contrary to proposed growth-stimulating effects of leptin. Osteocalcin in boys predicts gain in BMC size .