Obese and overweight adolescents in the final stages of sexual maturity presented higher bone mineral density in relation to their normal-weight counterparts; however, cohort studies will be necessary to evaluate the influence of such characteristic on bone resistance in adulthood and, consequently, on the incidence of osteopenia and osteoporosis at older ages.
Objective: to study bone density as a concomitant factor for obesity in post-pubertal adolescents, controlling for other variables that may interfere in such a relation.Methods: Study comprising 83 overweight and obese adolescents (BMI > P85) and 89 non obese ones (P5 < BMI < P85). Cases and controls were selected out of 1,420 students (aged 14-19) from a public school in the city of São Paulo. The bone mineral density of the lumbar spine (L2-L4 in g/cm 2 ) was assessed by dual-energy x-ray absorptiometry (LUNAR TM DPX-L). The variable bone density was dichotomized using 1.194 g/cm 2 as cutoff point. Bivariate analyses were conducted considering the prevalence of overweight and obesity followed by multivariate analysis (logistic regression) according to a hierarchical conceptual model.
Results:The prevalence of bone density above the median was twice more frequent among cases (69.3%) than among controls (32.1%). In the bivariate analysis such prevalence resulted in an odds ratio (OR) of 4.78. The logistic regression model showed that the association between obesity and mineral density is yet more intense with an OR of 6.65 after the control of variables related to sedentary lifestyle and intake of milk and dairy products.
Conclusion:Obese and overweight adolescents in the final stages of sexual maturity presented higher bone mineral density in relation to their normal-weight counterparts; however, cohort studies will be necessary to evaluate the influence of such characteristic on bone resistance in adulthood and, consequently, on the incidence of osteopenia and osteoporosis at older ages.J Pediatr (Rio J). 2005;81(4):337-42: Obesity, bone density, adolescent, osteoporosis.
Background
Considering that modification in body composition and growth velocity leads to alterations in zinc and copper nutritional status, the purpose of the study was to assess erythrocyte zinc and serum copper in adolescents of both genders, according to the stage of sexual maturity at different growth phases.
Methods
Two hundred and eighty-six adolescents were assessed, 157 were female, with body mass index Z-score between −2 and +2. Clinical biochemical measurements were assessed using atomic absorption spectrophotometry. Student’s t, Kruskal-Wallis, and Bonferroni tests were used.
Results
Median serum copper was superior, and zinc was inferior to respective reference values in all groups. Serum copper presented significant reduction in the final stages of pubertal development in males; in turn, erythrocyte zinc values increased linearly with the evolution of puberty stages in both genders. Comparison between genders in each stage of growth showed significant difference in peak acceleration and in deceleration for erythrocyte zinc and serum copper, with both being higher in females.
Conclusions
Serum copper is inversely influenced by modifications that occur with the evolution of puberty in males, whereas erythrocyte zinc is directly influenced in both genders, although always with deficient deposition. At peak acceleration and deceleration of growth, there is greater mobilization of erythrocyte zinc and serum copper in males, when compared with females, which does not occur at the onset of the acceleration of growth.
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