OBJETIVO: Verificar a prevalência de anemia em adolescentes (hemoglobina<12g/dL) em diferentes estágios de maturação sexual. MÉTADOS: Foi realizado estudo transversal com todos os adolescentes de quinta a oitava série em escola particular de São Paulo, por meio de dosagem de hemoglobina sangüínea (Hemocue®) e auto-avaliação para maturação sexual (fotos 5 estágios de Tanner), bem como indicadores sociais. Utilizou-se teste ''t'' de Student e teste não-paramétrico de Kruskal-Wallis para comparação de médias e Qui-quadrado para associação entre variáveis (p<0,05). RESULTADOS: Participaram desta pesquisa 118 alunos, sendo 66,9% do sexo feminino, com idade média 12,2±1,13 anos e 33,1% do masculino, com 12,0±1,18 anos. O nível médio de hemoglobina foi 13,2±1,08g/dL para meninas e 13,3±1,21g/dL para meninos (p>0,05). Observou-se aparente aumento do nível médio de hemoglobina com o desenvolvimento do adolescente. Detectou-se anemia em 11,0% dos adolescentes, a maioria na fase púbere, classificada como ''prevalência leve'' segundo a World Health Organization. Não foi encontrada associação entre indicadores sociais e anemia. CONCLUSÃO: O estudo apontou baixa prevalência de anemia, mas acima do esperado entre púberes de escola particular e indica tendência de aumento dos níveis de hemoglobina com o desenvolvimento sexual dos adolescentes. Devem ser realizados novos estudos de prevalência de anemia para se determinar sua causa entre adolescentes de diferentes níveis socioeconômicos.

OBJECTIVE: To assess the prevalence of anemia (hemoglobin level <12g/dL) in adolescents, according to their sexual maturation stage. METHODS: A cross-sectional study was conducted with all adolescents enrolled in 5th - 8th grades in a private school in the city of São Paulo. Their hemoglobin level was measured (using Hemocue®) and sexual development was self-evaluated (with the aid of pictures of the maturation stages proposed by Tanner). The social indicators evaluated were the per capita family income and maternal schooling. Student t test and non-parametric Kruskal-Wallis test were used for mean comparison and Chi-square-test for associations (p<0.05). RESULTS: We analyzed 118 students, of which 66.9% were females (aged 12.2±1.13 years) and 33.1% were males (aged 12.0±1.18 years). The mean hemoglobin level was 13.2±1.08 g/dL for females and 13.3±1.21 g/dL for males, with no significant difference. An apparent increase in the mean hemoglobin level was verified along with sexual development of the adolescents. Anemia was detected in 11% of them, most in the pubertal stage, which is classified by the World Health Organization as ''mild prevalence''. No association was found between social indicators and anemia prevalence. CONCLUSION: This study showed low prevalence of anemia at rates higher than expected during puberty in a private school and indicates a trend for increased hemoglobin levels in connection with sexual development of adolescents. Further studies on anemia prevalence should be carried out to establish the factors associated with this disease, having adolescents from different socioeconomic levels as subjects.