The influence of stress and cortisol on thyroid dysfunction.

Area of Science:

• Endocrinology
• Immunology
• Stress Physiology

Background:

• Chronic stress sustains activation of the hypothalamic-pituitary-adrenal (HPA) axis, leading to elevated cortisol.
• Cortisol impacts the hypothalamic-pituitary-thyroid (HPT) axis, thyroid hormone metabolism, and immune function.

Purpose of the Study:

• To review current evidence on how stress and cortisol influence thyroid function.
• To discuss effects on the HPT axis, peripheral metabolism, and autoimmunity.
• To explore potential clinical implications and therapeutic strategies.

Main Methods:

• Comprehensive literature search of clinical, population-based, and experimental studies from the last decade.
• Focused on associations between psychological stress, cortisol, thyroid dysregulation, deiodinase activity, and autoimmune thyroid disease.
• Summarized mechanistic pathways and therapeutic perspectives.

Main Results:

• Cortisol suppresses TRH and TSH, disrupts TSH circadian rhythm, and alters deiodinase activity (↓D1/↓D2, ↑D3), reducing T3 and increasing rT3.
• These changes contribute to subclinical hypothyroidism and non-thyroidal illness syndrome (NTIS).
• Chronic stress impairs immune homeostasis, increasing susceptibility to autoimmune thyroid diseases like Hashimoto's and Graves'.

Conclusions:

• Stress and cortisol significantly affect thyroid regulation via endocrine, metabolic, and immunological pathways.
• Assessing chronic stress and HPA axis activity can enhance thyroid disorder diagnosis.
• Stress-reduction interventions and micronutrient optimization may complement standard thyroid therapy, particularly for autoimmune thyroid disease.