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Chronobiology of pituitary-thyroid functions
G Y Nicolau1, E Haus, L Plîngă
1C. I. Parhon, Institute of Endocrinology, Bucharest, Romania.
Romanian Journal of Endocrinology
|January 1, 1992
Summary
This study reveals circadian and seasonal variations in thyroid hormones for children and elderly individuals. Children with endemic goiter exhibit subtle thyroid function abnormalities despite being euthyroid.
Area of Science:
- Endocrinology
- Chronobiology
- Pediatric Health
Background:
- Thyroid hormone regulation exhibits complex circadian and seasonal patterns.
- Endemic goiter can influence thyroid function, even in euthyroid individuals.
- Understanding these variations is crucial for accurate diagnosis and treatment.
Purpose of the Study:
- To investigate circadian and circannual variations in thyroid hormones and TSH in children and the elderly.
- To compare thyroid function rhythms between children with and without endemic goiter.
- To assess seasonal influences on thyroid parameters in these populations.
Main Methods:
- Cosinor analysis applied to blood samples collected every 4 hours over 24-hour periods.
- Study included 194 children and 166 elderly subjects across all four seasons.
- Comparison of thyroid parameters (T3, T4, TSH, TBG) between goitrous and non-goitrous children.
Main Results:
- Both children and elderly subjects displayed circadian and circannual rhythms in thyroid hormones and TSH.
- Children with endemic goiter showed altered circadian rhythms for T3, T4, and TBG compared to controls.
- TSH levels peaked in summer/fall, while thyroid hormones were highest in the cold season.
Conclusions:
- Circadian and seasonal variations in thyroid function are significant in both children and the elderly.
- Endemic goiter in children is associated with subtle disruptions in thyroid hormone rhythms.
- These findings highlight the importance of considering temporal factors in thyroid health assessment.