Your thyroid and adrenal glands work closely together. Chronic stress leads to less thyroid hormone being available in the body, leading to less energy, more brain fog, and increased hypothyroid symptoms WITH NORMAL THYROID LABS.
First, stress triggers a fight-or-flight reaction. Then, the brain signals the adrenals to produce stress hormones such as cortisol. These hormones are very helpful when you want to run away from a wild animal. However, when your stressors are chronic, there can be an imbalance in the body. Consequently, thyroid hormone production, digestion, and immune response can be slowed until the stress is resolved.
How Stress Impacts the Thyroid
1) Decreases thyroid hormone production The hypothalamus and pituitary slow down thyroid hormone production in response to increases in cortisol.
2) Reduces conversion of T4 to T3 High stress causes the storage form of thyroid hormone to be turned into reverse T3 (rT3) instead of the active T3 form.
3) Weakens immune system function Stress suppresses the immune system.
4) Causes thyroid hormone resistance Stress releases inflammatory cytokines making thyroid receptors less responsive to thyroid hormone.
5) Decreases unbound thyroid Elevations in cortisol over time can cause estrogen accumulation. This can mean an uptick in TBG, and thyroid-binding globulin. TBG binds to thyroid hormone and decreases the availability of free T3.
6) May lead to intestinal permeability Cortisol weakens the protective barrier in the gut and can lead to intestinal permeability.