Reviewed By Deborah Wexler MD, Assistant Professor of Medicine, Harvard Medical School, Endocrinologi…st, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.more »
Definition
Hypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone.
The thyroid gland is located in the front of the neck just below the voice box (larynx). It releases hormones that control metabolism.
The most common cause of hypothyroidism is inflammation of the thyroid gland, which damages the gland's cells. Autoimmune or Hashimoto's thyroiditis, in which the immune system attacks the thyroid gland, is the most common example of this. Some women develop hypothyroidism after pregancy (often referred to as "postpartum throiditis").
Sheehan syndrome, a condition that may occur in a woman who bleeds severely during pregnancy or childbirth and causes destruction of the pituitary gland
A physical examination may reveal a smaller-than-normal thyroid gland, although sometimes the gland is normal size or even enlarged (goiter). The examination may also reveal:
The purpose of treatment is to replace the thyroid hormone that is lacking. Levothyroxine is the most commonly used medication. Doctors will prescribe the lowest dose that effectively relieves symptoms and brings the TSH level to a normal range. If you have heart disease or you are older, your doctor may start with a very small dose.
Lifelong therapy is required unless you have a condition called transient viral thyroiditis.
You must continue taking your medication even when your symptoms go away. When starting your medication, your doctor may check your hormone levels every 2 - 3 months. After that, your thyroid hormone levels should be monitored at least every year.
Important things to remember when you are taking thyroid hormone are:
Do NOT stop taking the medication when you feel better. Continue taking the medication exactly as directed by your doctor.
If you change brands of thyroid medicine, let your doctor know. Your levels may need to be checked.
Some dietary changes can change the way your body absorbs the thryoid medicine. Talk with your doctor if you are eating a lot of soy products or a high-fiber diet.
Thryoid medicine works best on an empty stomach and when taken 1 hour before any other medications. Do NOT take thyroid hormone with calcium, iron, multivitamins, alumin hydroxide antacids, colestipol, or other medicines that bind bile acids, or fiber supplements.
After you start taking replacement therapy, tell your doctor if you have any symptoms of increased thyroid activity (hyperthyroidism) such as:
Rapid weight loss
Restlessness or shakiness
Sweating
Myxedemacoma is a medical emergency that occurs when the body's level of thyroid hormones becomes extremely low. It is treated with intravenous thyroid hormone replacement and steroid medications. Some patients may need supportive therapy (oxygen, breathing assistance, fluid replacement) and intensive-care nursing.
Expectations (prognosis)
In most cases, thyroid levels return to with proper treatment. However, thyroid hormone replacement must be taken for the rest of your life.
Myxedema coma can result in death.
Complications
Myxedema coma, the most severe form of hypothyroidism, is rare. It may be caused by an infection, illness, exposure to cold, or certain medications in people with untreated hypothyroidism.
