What Causes Hypothyroidism
90% of cases of hypothyroidism are due to an autoimmune attack on the thyroid gland by either thyroperoxidase antibodies (TPOAb) or by thyroglobulin antibodies (TgAb), a condition called Hashimoto’s thyroiditis. What this means is that the body creates immune cells that attack the gland so that function declines over time. This condition can be triggered by gluten in gluten-sensitive individuals. Similarly, in these people, gluten avoidance for at least 3 months may help lower antibody levels to a normal range.
The thyroid gland needs iodine, selenium, zinc and thyroxine in order to function properly and create thyroid hormones. If you are deficient in any of these nutrients, you may experience symptoms of hypothyroidism. Iodine is found in iodized salt and sea vegetables (e.g. dulse flakes), selenium is abundantly found in Brazil nuts, and zinc is found in beef, cashews, pumpkin seeds, etc. Thyroxine, the amino acid that primarily makes up the thyroid hormones, is found in most sources of protein.
In some people, the enzyme that is used to convert T4 into T3 doesn’t function properly and results in normal levels of TSH and T4 but severely deficient levels of T3. These individuals are often told by their doctors that their thyroid function is “normal” even though they do not feel normal! This is also why some people who are medicated with synthroid (thyroxine/T4) may feel like their medication is doing nothing for them.
Thyroid Hormone Resistance
Thyroid hormone resistance is similar to insulin resistance in diabetics. In this condition, the body’s cells are unresponsive to thyroid hormones. In these individuals, T3 and T4 levels can be normal but TSH levels are elevated.
Secondary or Tertiary Hypothyroidism
Secondary and tertiary hypothyroidism are extremely rare and are caused by disorders within the pituitary gland or hypothalamus in the brain. There are usually other concerning symptoms than just those associated with hypothyroidism in these cases.