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A longitudinal study of total and free thyroid hormones and thyroxine binding globulin during normal puberty
D B Dunger1, J A Perkins, T P Jowett
1Department of Growth and Development, University College and Middlesex School of Medicine, London, UK.
Insights
Thyroid hormone levels, including free thyroxine (T4) and free triiodothyronine (T3), change significantly during puberty in children. These changes, particularly in free T4, show distinct patterns in girls and boys, impacting pubertal growth.
Area of Science:
- Pediatric Endocrinology
- Endocrinology
- Human Physiology
Background:
- Thyroid hormones are critical for normal pubertal development.
- Previous studies have not fully defined dynamic changes in thyroid hormones during puberty.
Purpose of the Study:
- To characterize longitudinal changes in total T4, free T4, free T3, and thyroxine-binding globulin during puberty in normal children.
- To investigate potential sex-specific differences in these hormonal shifts.
Main Methods:
- Serum samples from 39 children (20 girls, 19 boys) aged 10-15 years were collected every 6 months.
- Assays for total T4, free T4, free T3, and thyroxine-binding globulin were performed using validated non-analogue methods.
Main Results:
- Free T4 levels exhibited a nadir around pubertal stages 3-4 in both sexes, with distinct temporal patterns in girls and boys.
- Total T4 changes mirrored free T4 but with a slight delay.
- Thyroxine-binding globulin remained stable in girls but decreased slightly in boys during late puberty.
- Free T3 levels progressively fell in girls after age 12.5, while remaining stable in boys.
Conclusions:
- Puberty is associated with significant, sex-specific alterations in free thyroid hormone levels.
- These findings provide a detailed profile of thyroid hormone dynamics during this critical developmental period.
- Further research may explore the clinical implications of these pubertal thyroid hormone changes.
Abstract:
Thyroid hormones are essential for normal pubertal growth, yet the changes in total and, especially, free thyroid hormones and thyroxine-binding globulin during puberty have not been adequately defined. Serum from 39 normal children (20 girls, 19 boys) between the ages of 10 and 15 years were assayed for total T4, free T4, free T3 and thyroxine-binding globulin at 6-monthly intervals; the free hormone assays were valid, non-analogue methodologies. In the girls, free T4 levels fell from 15.7 +/- 0.6 pmol/l at 10 years to 13.0 +/- 0.6 (p less than 0.001) at 12.5 years before rising to 15.9 +/- 0.7 at 15 years; this nadir occurred at puberty stages 3-4. Changes in total T4 followed a similar pattern with a slight delay in the nadir (13 years, puberty stage 4). In the boys, free T4 fell from 16.3 +/- 0.6 pmol/l at 10 years to 14.3 +/- 0.3 at 13.5 years, then rising to 15.4 +/- 0.5 at 15 years; the nadir again occurred at puberty stages 3-4. The corresponding nadir in total T4 which occurred at puberty stages 4-5 was not apparent by age analysis. Thyroxine-binding globulin concentrations remained unchanged in the girls, but fell slightly in the boys during later puberty. Free T3 concentrations in the girls showed a progressive fall after 12.5 years which was significant by the age of 14 when most had been in puberty stage 5 for more than 1 year. The boys showed no change of free T3 concentration throughout the study.(ABSTRACT TRUNCATED AT 250 WORDS)