Hyperthyroidism
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Hyperthyroidism

(Graves' Disease; Overactive Thyroid)

En Español (Spanish Version)More InDepth Information on This Condition

Definition

Hyperthyroidism happens when the thyroid gland produces too much thyroid hormone. The thyroid gland is a butterfly-shaped gland in the front of the neck. It produces hormones that control metabolism. The most common form is Graves' disease.

The Thyroid Gland

© 2008 Nucleus Medical Art, Inc.

Causes

Graves' disease occurs when:

  • Immune system produces antibodies that cause the thyroid gland to overproduce thyroid hormone
  • Thyroid nodules or tumors
  • Toxic uninodular goiter—a single nodule in the thyroid gland
  • Toxic multinodular goiter—multiple areas in the thyroid gland which overproduce thyroid hormone
  • Subacute thyroiditis—inflammation of the thyroid gland (often later leads to hypothyroidism )

Risk Factors

These factors increase your chance of developing Graves' disease:

  • Sex: female (eight times more common in women)
  • Age: between 30-40 years old
  • Pregnancy: postpartum thyroiditis (hyperthyroidism followed by hypothyroidism)
  • Family history of Graves' disease
  • Certain viral infections
  • Smoking

Tell your doctor if you have these risk factors.

Symptoms

Symptoms come on slowly. They may be mistaken for stress. As the thyroid becomes more overactive, symptoms may include:

  • Fatigue
  • Unexplained weight loss with increased appetite
  • Restlessness
  • Changes in libido
  • Muscle weakness and wasting, especially in the elderly
  • Heat intolerance
  • Tremors
  • Enlarged thyroid gland ( goiter )
  • Heart palpitations
  • Increased sweating
  • Nervousness
  • Irritability
  • Redness, swelling, and protrusion of the eyes
  • Lumpy, reddish thickening of the skin in front of the shins
  • Shortness of breath
  • Increased number of bowel movements
  • Irregular or no menstrual period
  • Heart failure or atrial fibrillation , especially in the elderly

Diagnosis

The doctor will ask about your symptoms and medical and family history, and perform a physical exam. The exam usually reveals:

  • Enlarged thyroid gland
  • Rapid pulse
  • Warm, moist skin
  • Several of the symptoms listed above

Your doctor may order the following tests:

  • Blood tests
    • Thyroid stimulating hormone (TSH), currently the best screening test
    • Free T4 and free T3
    • Thyroid autoantibodies (TSH receptor antibody)
    • Thyroid scan—may be needed to differentiate between Graves' disease and other causes
  • Radioactive iodine uptake test—measures how active thyroid is in taking up the iodine
  • Needle biopsy of the thyroid—may be needed

Treatment

Treatment will depend on:

  • Age
  • Severity of symptoms
  • Cause of hyperthyroidism
  • Pregnancy status

Treatment options include:

Antithyroid Drugs

Antithyroid drugs work best for Graves' disease. Examples include:

  • Methimazole
  • Propylthiouracil

If the disease goes into remission, you may no longer need medication.

Radioactive Iodine

This is a common treatment in the US. Radioactive iodine is taken orally. It is then absorbed by the thyroid gland. Once there, it damages most of the thyroid cells. These cells can no longer produce thyroid hormones. Within days, the excess iodine passes out of the body in the urine or changes into a nonradioactive state. You may need to take a daily thyroid supplement.

Surgery

Surgery is rarely used for hyperthyroidism. Exceptions include:

  • Young children
  • Pregnant women
  • Individuals with a very large goiter that causes either swallowing or breathing problems

Most patients take antithyroid medication before surgery. After surgery, you may need to take a daily thyroid supplement.

Beta-blockers

You may need to take beta-blockers . These drugs relieve rapid heart rate and jitters. Examples include:

  • Propranolol
  • Atenolol
  • Metoprolol

Eye Protection

If there are eye symptoms, your doctor may prescribe:

  • Eye protection before sleep
  • Artificial tears
  • Sunglasses

Prevention

To help reduce your chance of getting hyperthyroidism, take the following steps:

  • Avoid taking in too much iodine (iodized salt, salt water fish).
  • Avoid taking too high a dose of thyroid medication.
  • Get regular screening if you have a family history of hyperthyroidism.
  • If you smoke, quit .

RESOURCES:

The American Thyroid Association
http://www.thyroid.org/

National Graves' Disease Foundation
http://www.ngdf.org/

CANADIAN RESOURCES

Health Canada
http://www.hc-sc.gc.ca/index_e.html/

Thyroid Foundation of Canada
http://www.thyroid.ca/

References:

American Association of Clinical Endocrinologists. Medical guidelines for clinical practice for the evaluation and treatment of hyperthyroidism and hypothyroidism. Endocrine Practice . 2002;8:457-469.

American Association of Clinical Endocrinologists website. Available at: http://www.aace.com/ .

Graves' disease. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php . Updated June 2008. Accessed July 7, 2008.

Reducing your risk of hyperthyroidism. EBSCO Health Library website. Available at: http://www.ebscohost.com/thisTopic.php?marketID=15topicID=81 . Updated May 2007. Accessed July 7, 2008.

Shomon M. Frequently asked questions on Graves' disease & hyperthyroidism. Thyroid-Info website. Available at: http://www.thyroid-info.com/articles/hyperthyroidism-faq.htm . Updated July 2008. Accessed July 7, 2008.

Subclinical hyperthyroidism. N Engl J Med . 2001;345:512-516.

Van Geest RJ, Sa sim IV, Koppeschaar HP, et al. Methylprednisolone pulse therapy for patients with moderately severe Graves' orbitopathy: a prospective, randomized, placebo-controlled study. Eur J Endocrinol. 2008;148:229-237.

Weetman AP. Graves' disease. N Engl J Med. 2000;343:1236-1248.

Woeber K. Update on the management of hyperthyroidism and hypothyroidism. Arch Intern Med . 2000;160:1067-1071.



Last reviewed March 2008 by David Juan, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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