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Alterations in the hypothalamic-pituitary-thyroid axis after prolonged residence in Antarctica
Clinical Endocrinology
|July 1, 1986
Summary
Human cold adaptation is poorly understood. Antarctic duty led to significant decreases in thyroid hormones (T3) and increased thyroid-stimulating hormone (TSH) response, suggesting thyroid axis alterations in polar environments.
Area of Science:
- Physiology
- Endocrinology
- Environmental Medicine
Background:
- Increasing human presence in polar regions necessitates understanding physiological adaptation.
- Cold adaptation mechanisms in humans remain largely uncharacterized.
- Euthermic mammals utilize non-shivering thermogenesis for cold adaptation.
Purpose of the Study:
- To prospectively investigate the hypothalamic-pituitary-thyroid axis response in men stationed in the Antarctic.
- To assess changes in thyroid hormone levels and TSH response during prolonged cold exposure.
- To explore potential hormonal adaptations to polar environments.
Main Methods:
- Prospective study of 17 euthyroid men.
- Measurements taken before, during, and after Antarctic duty.
- Assessed serum total and free T4, total and free T3, and TSH response to TRH.
Main Results:
- Serum total and free T4 showed non-significant decreases.
- Significant reductions observed in serum total and free T3 levels.
- Integrated TSH response to TRH administration increased by 50% by study end.
- Circadian cortisol rhythm remained stable.
Conclusions:
- Prolonged Antarctic residence induces significant alterations in the human thyroid axis.
- Observed thyroid hormone changes are likely linked to chronic cold exposure.
- Further research is needed to fully elucidate human cold adaptation mechanisms.