Iodine deficiency may cause hypothyroidism as well because iodine is an essential element used to synthesize thyroid hormones. The body does not produce iodine naturally therefore, we need to obtain iodine from dietary sources such as dairy products, shellfish, iodized salt, soy milk and seaweed. Overall when there is a iodine deficiency in the body then thyroid hormones such as T3 (triiodothyronine) and T4 (thyroxine) cannot be produced and a goiter, which is an enlarged thyroid gland, may develop instead.
Pituitary gland damage may also contribute to hypothyroidism. The signal to produce thyroid hormones comes from the hypothalamus in the brain and travels to the pituitary gland, another gland found in the brain. If the pituitary gland is damaged, then the signal from the pituitary gland to the thyroid gland is blocked, and the thyroid gland may not receive the signal to produce or slow production of thyroid hormones.
Other causes of hypothyroidism are being born with a damaged or even missing a thyroid gland. This includes having a part or even the whole thyroid gland surgically removed. Thyroid hormones cannot be produced if there is a dysfunctional thyroid gland and this dysfunctional thyroid may interfere with the body's daily functions.