Objective: This study was planned to describe thyroid functional status in different stages of puberty.
Study design: We collected data from five schools across different geographical zones of Delhi. All children who consented were evaluated for anthropometry, pubertal stage, goitre status, serum free T3 (FT3), free T4 (FT4), TSH, anti-TPO (thyroid peroxidase) antibodies and thyroid ultrasound. From this sample, a disease- and risk-free or 'reference population' was obtained by excluding those with history of thyroid disease or use of thyroid medications, family history of thyroid disease, goitre, hypoechogenicity or nodularity on ultrasound or positive antithyroid antibodies.
Results: The 'total population' comprised 3722 children; the 'reference population' comprised 2134 subjects. The mean, median, 3rd and 97th percentiles of serum FT3, FT4 and TSH for each stage of puberty were obtained. In both boys and girls, FT3 increased with entry into puberty and either stayed constant or declined marginally after stage 3 of puberty. In contrast, in both genders, FT4 decreased with entry into puberty and stayed relatively constant after stage 3 of puberty. TSH levels declined through puberty in boys, but remained largely unchanged in girls. An increased conversion of T4 to T3 is the possible explanation for this finding.
Conclusions: This large community-based study in school-age children using strict exclusion criteria provides data of thyroid function in the various stages of puberty. There is no evidence of 'thyroidarche' during or preceding puberty.
© 2011 Blackwell Publishing Ltd.