There are several ways that stress can influence thyroid function. Stress causes the release of the hormone cortisol from the adrenal glands. High levels of cortisol inhibit the production of TSH, a hormone from the pituitary gland that stimulates the thyroid gland to produce its hormones, thyroxine (T4) and triiodothyronine (T3).
A high cortisol level can also impair the conversion of the T4 to T3, which is the active form of the hormone. Under chronic stress, the liver has less ability to metabolize excess estrogens in the blood.
This then increases the level of thyroid binding globulin (TBG), the protein that transports thyroid hormones. Thyroid hormone bound to TBG cannot exert a physiological effect and must be separated from the protein to have its action. Studies have also shown that inflammatory cytokines produced during the stress response suppress thyroid receptor site binding so further reduce the activity of thyroid hormones.
These mechanisms combine to reduce the ability of the thyroid gland to carry out its metabolic functions. As levels of TSH and thyroid hormones often appear in the normal range this suggests that the predominant action of stress and cortisol release is to reduce the physiological action rather than the levels of thyroid hormones present in the blood.
Reducing the effects of stress can restore thyroid function. Stress management is vital. This includes relaxation techniques, healthy diet, exercise and more sleep. But treatment with herbal medicine can also be very effective. The key herbs used to restore adrenal function are called adaptations. Herbs included in this group are Siberian ginseng, Ashwagandha, Holy Basil, Rhodiola and Schisandra. These hormones act by normalising cortisol release and restoring adrenal function. If treatment with adatogenic herbs is combined with other herbs, including those to improve liver function, normal thyroid function can be restored and symptoms reduced.