Ferro, cobre e zinco em adolescentes no estirão pubertário

Abstract

To examine iron, copper and zinc nutritional status and their correlation with Body Mass Index (BMI), serum and dietetic levels in adolescents during the pubertal growth spurt. A descriptive cross-sectional study involving a sample of 47 adolescents out of 360 patients (19 boys, whose ages ranged from 12.3 to 16 years and 28 girls, whose ages ranged from 11.1 to 13.6 years), who were seen at a clinic for adolescents from March to December 1999. The variables analyzed were: Diet (24 hours Dietary Recall, Food Frequency Intake Questionnaire and Food Register Methods) to determine iron, copper and zinc intake; anthropometry (weight and height) to check BMI; biochemistry (measure of serum iron level through a Diagnóstica kit in vitro; ferritin through Immulite kit, and atomic absorption spectrophotometry for biochemical evaluation of serum iron, ferritin, copper and zinc. Spearman coefficient correlation was used for statistical analysis. Forty seven adolescents during pubertal growth spurt showed adequate ingestion: iron (95% and 36%), copper (53% and 57%) and zinc (21% and 21%) in males and females, respectively. Most of them were eutrophic according to the BMI percentiles. Biochemically, boys presented normal values for serum iron and zinc in the whole sample, 95% for copper and 84% for ferritin. Girls also presented normal values for iron and zinc values in the whole sample, 96.4% for copper and 96% for ferritin. There were no statistically significant correlation between BMI and serum Fe, ferritin, Cu and Zn concentrations and between serum concentration and dietetic ingestion of the studied minerals, neither between serum iron and ferritin. It is not clear if serum levels of Zn and Cu are floating during the growth process or if each adolescent has a stable level of these minerals during the pubertal growth spurt. Normal Fe, Cu and Zn serum levels in most adolescents evaluated may reflect the organism ability to accomplish homeostatic adjustments.