If you have coronary artery disease or are at risk for it, your doctor will prescribe a smaller dose of hormone tablets in the beginning. Replacing the thyroid hormone too quickly can worsen coronary artery disease and, in some cases, can prompt a heart attack. Women prone to osteoporosis may have greater bone loss if they are treated with too much thyroid hormone. They, too, will be given a smaller dose. Usually hypothyroidism improves within a week after the hormone therapy is begun.
All symptoms disappear within a few months.
In most cases, however, you must continue this treatment for the rest of your life. Mild hypothyroidism causes no symptoms. If the disease progresses, however, it can become disabling over a long time if it is not treated. If not treated, long-lasting thyroiditis can cause goiter, a swelling of the thyroid gland. The thyroid gland may look or feel enlarged.