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Definition
Hyperthyroidism is a disease in which 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 of hyperthyroidism is Graves' disease.
The Thyroid Gland
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Causes
Graves' disease occurs when your own immune system produces antibodies that stimulate overproduction of thyroid hormone. Other common causes of hyperthyroidism include:
- Thyroid nodules or tumors
- Toxic uninodular goitera single nodule in the thyroid gland
- Subacute thyroiditisinflammation of the thyroid gland (often later leads to hypothyroidism )
- Toxic multinodular goitermultiple areas in the thyroid gland which overproduce excess amount of thyroid hormone
Risk Factors
A risk factor is something that increases your chance of getting a disease or condition.
Risk factors for Graves' disease include:
- Sex: female (eight times more common in women)
- Age: peak incidence between 30-40 years old
- Pregnancy: postpartum thyroiditis (first hyperthyroid followed by hypothyroid)
- History of family members with Graves' disease
- Certain viral infections
Symptoms
Symptoms come on gradually and may be mistaken for stress. As the thyroid becomes more overactive, symptoms may include:
FatigueUnexplained weight loss with increased appetiteRestlessnessChanges in libidoMuscle weakness and wasting especially in the elderlyHeat intoleranceTremorsEnlarged thyroid gland (goiter)Heart palpitationsIncreased sweatingNervousnessIrritabilityRedness, swelling, and protrusion of the eyesLumpy, reddish thickening of the skin in front of the shinsShortness of breathIncreased number of bowel movementsIrregular or no menstrual periodHeart 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 the following: Enlarged thyroid glandRapid pulseWarm, moist skinSeveral of the symptoms listed above Blood tests will be ordered to confirm the diagnosis, including: Thyroid stimulating hormone (TSH), currently the best screening testFree T4 and free T3Thyroid autoantibodies (TSH receptor antibody) Additionally, a test called a thyroid scan may be needed to help differentiate between Graves' disease and other causes of hyperthyroidism. Your doctor will most likely order a radioactive iodine uptake test, which measures how active your thyroid is in taking up the iodine. Occasionally, a needle biopsy of the thyroid is needed.
Treatment Treatment will depend on: AgeSeverity of symptomsCause of hyperthyroidismPregnancy statusTreatment options include: Antithyroid DrugsBest suited for Graves' disease, antithyroid drugs (methimazole, propylthiouracil) suppress thyroid synthesis. If the disease goes into remission, you may no longer need the medication. Radioactive IodineThis is the most commonly used definitive treatment in the US. Radioactive iodine is taken orally and absorbed by the thyroid gland where it damages most of the thyroid cells. The damaged cells can no longer produce thyroid hormones. Within days, the excess radioactive iodine either passes out of the body in the urine or changes into a nonradioactive state. Eventually, you will need to take a daily thyroid replacement. SurgerySurgical treatment is rarely used in the treatment of hyperthyroidism except in young children, pregnant women, and those individuals with a very large goiter that causes either swallowing or breathing problems. Most patients take antithyroid medication prior to surgery. If the surgery leaves you with too little production of thyroid hormone, you will need to take a daily thyroid supplement. Beta-blockersUntil the treatments above take effect, you may need to take beta-blockers (eg, propranolol, atenolol, metoprolol) to relieve rapid heart rate and jitters.
Eye ProtectionIf there are eye symptoms, eye protection before sleep, artificial tears, and sunglasses will be prescribed by your doctor. Prevention There are several ways to prevent getting hyperthyroidism including: Eat a diet with an adequate amount of iodine.Get regular screening for hyperthyroidism if there is someone in your immediate family with this disease or you have another autoimmune disease. RESOURCES: The American Thyroid Associationhttp://www.thyroid.org National Graves' Disease Foundationhttp://www.ngdf.org CANADIAN RESOURCES Health Canadahttp://www.hc-sc.gc.ca/index_e.html Thyroid Foundation of Canadahttp://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. N Engl J Med . 2000 Oct 26. To ft AD. 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.
Woeber K. Update on the management of hyperthyroidism and hypothyroidism. Arch Intern Med . 2000;160:1067-1071. Last reviewed March 2008 by David Juan, MDPlease 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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