Hypothyroidism
Multimedia
Definition
Hypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone.
See also:
Alternative Names
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.
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 pregnancy (often referred to as "postpartum thyroiditis").
Other common causes of hypothyroidism include:
Congenital (birth) defects
Radiation treatments to the neck to treat different cancers, which may also damage the thyroid gland
Radioactive iodine used to treat an overactive thyroid (hyperthyroidism)
Surgical removal of part or all of the thyroid gland, done to treat other thyroid problems
Viral thyroiditis, which may cause hyperthyroidism and is often followed by temporary or permanent hypothyroidism
Certain drugs can cause hypothyroidism, including:
Risk factors include:
Age over 50 years
Being female
References
Fatourechi V. Subclinical hypothyroidism: an update for primary care physicians. Mayo Clin Proc. 2009;84(1):65-71.
Ladenson P, Kim M. Thyroid. In: Goldman L and Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders; 2007:chap 244.
Vaidya B, Pearce SH. Management of hypothyroidism in adults. BMJ. 2008;337.
Allahabadia A, Razvi S, Abraham P, Franklyn J. Diagnosis and treatment of primary hypothyroidism. BMJ. 2009 Mar 26;338.
Review Date: 4/19/2010
Reviewed By: Ari S. Eckman, MD, Division of Endocrinology and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., 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 physician 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. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
Alternative Names
Myxedema; Adult hypothyroidism
Symptoms
Early symptoms:
Late symptoms, if left untreated:
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:
A chest x-ray may show an enlarged heart.
Laboratory tests to determine thyroid function include:
Lab tests may also reveal:
References
Fatourechi V. Subclinical hypothyroidism: an update for primary care physicians. Mayo Clin Proc. 2009;84(1):65-71.
Ladenson P, Kim M. Thyroid. In: Goldman L and Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders; 2007:chap 244.
Vaidya B, Pearce SH. Management of hypothyroidism in adults. BMJ. 2008;337.
Allahabadia A, Razvi S, Abraham P, Franklyn J. Diagnosis and treatment of primary hypothyroidism. BMJ. 2009 Mar 26;338.
Review Date: 4/19/2010
Reviewed By: Ari S. Eckman, MD, Division of Endocrinology and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., 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 physician 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. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
Alternative Names
Myxedema; Adult hypothyroidism
Treatment
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 effectively relieves symptoms and brings your 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 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.
After you start taking replacement therapy, tell your doctor if you have any symptoms of increased thyroid activity (hyperthyroidism) such as:
Myxedema coma 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 normal 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.
Symptoms and signs of myxedema coma include:
Below normal temperature
Decreased breathing
- Unresponsiveness
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:
References
Fatourechi V. Subclinical hypothyroidism: an update for primary care physicians. Mayo Clin Proc. 2009;84(1):65-71.
Ladenson P, Kim M. Thyroid. In: Goldman L and Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders; 2007:chap 244.
Vaidya B, Pearce SH. Management of hypothyroidism in adults. BMJ. 2008;337.
Allahabadia A, Razvi S, Abraham P, Franklyn J. Diagnosis and treatment of primary hypothyroidism. BMJ. 2009 Mar 26;338.
Review Date: 4/19/2010
Reviewed By: Ari S. Eckman, MD, Division of Endocrinology and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., 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 physician 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. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
Alternative Names
Myxedema; Adult hypothyroidism
Prevention
There is no prevention for hypothyroidism.
Screening tests in newborns can detect hypothyroidism that is present from birth (congenital hypothyroidism).
References
Fatourechi V. Subclinical hypothyroidism: an update for primary care physicians. Mayo Clin Proc. 2009;84(1):65-71.
Ladenson P, Kim M. Thyroid. In: Goldman L and Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders; 2007:chap 244.
Vaidya B, Pearce SH. Management of hypothyroidism in adults. BMJ. 2008;337.
Allahabadia A, Razvi S, Abraham P, Franklyn J. Diagnosis and treatment of primary hypothyroidism. BMJ. 2009 Mar 26;338.
Review Date: 4/19/2010
Reviewed By: Ari S. Eckman, MD, Division of Endocrinology and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., 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 physician 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. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
Review Date: 4/19/2010
Reviewed By: Ari S. Eckman, MD, Division of Endocrinology and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., 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 physician 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. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.