Bone mass and body composition in children and adolescents with primary hypertension: preliminary data

Because primary hypertension (PH) is associated with calcium metabolism, it is hypothesized that PH may be related to osteoporosis risk. The study aimed to evaluate the relationship between body composition and bone strength in hypertensive adolescents. Total body scans using x-ray absorptiometry (DPX-L, GE Healthcare) were performed in 94 PH children aged 6 to 18 years (21 girls and 73 boys). References of healthy control subjects were used for the calculation of Z scores (age and gender matched), SD scores (height and gender matched), and SDs scores (weight and gender matched). Total body bone mineral density, total body bone mineral content (TBBMC), lean body mass (LBM), and fat mass (FM) were investigated. Relative bone strength index was calculated as the TBBMC:LBM ratio. As evidenced by Z scores, PH case subjects had slightly higher total body bone mineral density, TBBMC, and LBM compared with healthy subjects. Reduced LBM/body weight (BW) Z scores of -1.9+/-1.5 and -1.2+/-1.4, increased FM Z scores of +2.5+/-2.5 and +1.7+/-2.0, and increased FM/BW Z scores of +1.6+/-1.3 and +1.1+/-1.4 were noted in girls and boys compared with healthy subjects, respectively (P<0.001). When increased BW was controlled for, PH girls differed in SDs scores for LBM (-1.4+/-1.7; P<0.01), FM (+1.6+/-2.2; P<0.05), FM/BW (+0.9+/-1.0; P<0.05), and FM/LBM (+1.3+/-1.4; P<0.01) but not for total body bone mineral density (+0.2+/-1.0; P value not significant), TBBMC (-1.2+/-1.6; P=0.07), LBM/BW (-0.7+/-1.0; P=0.07), and TBBMC/LBM (-1.0+/-2.1; P value not significant), when compared with respective SDs scores of -0.3+/-1.1, +0.3+/-1.1, +0.3+/-1.0, +0.3+/-1.0, -0.2+/-1.0, -0.6+/-1.9, -0.3+/-1.0, and -0.2+/-1.0 in PH boys. In conclusion, PH adolescents had increased FM and an imbalanced relationship among BW, FM, and LBM. In PH girls, bone strength, although proper for chronological age and body height, was lower than expected for BW.