Toggle: English / Spanish
Hypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone.
Myxedema; Adult hypothyroidism
Causes, incidence, and risk factors
The thyroid gland is located in the front of the neck just below the voice box (larynx). It releases hormones that control metabolism.
Hypothyroidism, or underactive thyroid, is more common in women and people over age 50.
The most common cause of hypothyroidism is thyroiditis. Swelling and inflammation damage the thyroid gland's cells. Causes of this problem include:
An attack of the thyroid gland by the immune system
Cold or other respiratory infection
Pregnancy (often called "postpartum thyroiditis")
Other causes of hypothyroidism include:
- Certain drugs, such as lithium and amiodarone
Congenital (birth) defects
Radiation treatments to the neck or brain to treat different cancers
Radioactive iodine used to treat an overactive thyroid gland
Surgical removal of part or all of the thyroid gland
, a condition that may occur in a woman who bleeds severely during pregnancy or childbirth and causes the destruction of the pituitary gland
Late symptoms, if left untreated:
- Decreased taste and smell
- Puffy face, hands, and feet
- Slow speech
- Thickening of the skin
- Thinning of eyebrows
Signs and tests
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:
Coarse features of the face
Pale or dry skin, which may be cool to the touch
Swelling of the arms and legs
Thin and brittle hair
Lab tests to determine thyroid function include:
Other tests that may be done:
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 possible that relieves your symptoms and brings your blood hormone levels back to normal.
- If you have heart disease or you are older, your doctor may start you on a very small dose.
- Most people with an underactive thyroid will need lifelong therapy.
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:
Do NOT stop taking the medication when you feel better. Continue taking them exactly as your doctor prescribed.
If you change brands of thyroid medicine, let your doctor know. Your levels may need to be checked.
What you eat can change the way your body absorbs the thyroid medicine. Talk with your doctor if you are eating a lot of soy products or are on a high-fiber diet.
Thyroid medicine works best on an empty stomach and when taken 1 hour before any other medications.
Do NOT take thyroid hormone with fiber supplements, calcium, iron, multivitamins, aluminum hydroxide antacids, colestipol, or medicines that bind bile acids.
While you are taking thyroid replacement therapy, tell your doctor if you have any symptoms that suggest your dose is too high, such as:
Myxedema coma is a medical emergency that occurs when the body's level of thyroid hormones becomes very 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.
In most cases, thyroid levels return to normal with proper treatment. However, you must take thyroid hormone replacement for the rest of your life.
Myxedema coma can result in death.
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.
Symptoms and signs of myxedema coma include:
Other complications are:
People with untreated hypothyroidism are at increased risk for:
People treated with too much thyroid hormone are at risk for angina or heart attack, as well as osteoporosis (thinning of the bones).
Calling your health care provider
Call your health care provider if you have symptoms of hypothyroidism (or myxedema).
If you are being treated for hypothyroidism, call your doctor if:
There is no prevention for hypothyroidism.
Screening tests in newborns can detect hypothyroidism that is present from birth (congenital hypothyroidism).
Brent GA, Davies TF. Hypothyroidism and thyroiditis. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, et al. Williams Textbook of Endocrinology. 12th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 13.
Kim M, Ladenson P. Thyroid. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 233.
- Last Reviewed on 06/04/2012
- David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by Shehzad Topiwala, MD, Chief Consultant Endocrinologist, Premier Medical Associates, The Villages, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2013 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
This page was last updated: May 31, 2013