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.
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 goiter–a single nodule in the thyroid gland
-
Subacute thyroiditis–inflammation of the thyroid gland (often later leads to hypothyroidism)
-
Toxic multinodular goiter–multiple 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:
-
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/family history, and perform a physical exam. The exam usually reveals the following:
Blood tests will be ordered to confirm the diagnosis including thyroid stimulating hormone (TSH), free T4 and free T3 and TSH receptor antibody.
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. In a needle biopsy, a sample of thyroid tissue is removed with a needle and tested.
Treatment
Treatment will depend on:
-
Your age
-
Severity of symptoms
-
Cause of hyperthyroidism
-
Pregnancy status
Treatment options include:
Anti-thyroid Drugs
Anti-thyroid drugs (methimazole, propylthiouracil) suppress thyroid synthesis. They are best suited for Graves' disease. If the Graves' disease goes away, you can stop taking the medication.
Radioactive Iodine
This is the most commonly used definite treatment in the US. Radioactive iodine is taken orally and absorbed by the thyroid gland where it damages some 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.
Surgery
Surgical treatment is rarely used in the treatment of hyperthyroidism except in young children, pregnant women, and those individuals with very large goiter that causes either swallowing or breathing problems. Most patients take anti-thyroid 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-blockers
Until the treatments above take effect, you may need to take beta-blockers (propranolol, atenolol, metoprolol) to relieve rapid heart rate and jitters.
Eye Protection
If 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:
RESOURCES:
The American Thyroid Association
http://www.thyroid.org
National Graves' Disease Foundation
http://www.ngdf.org
References:
American Association of Clinical Endocrinologists website. Available at: http://www.aace.com/.
American Association of Clinical Endocrinologisits. Medical guidelines for clinical practice for the evaluation and treatment of hyperthyroidism and hypothyroidism. Endorcine Practice. 2002; 8:457-69.
Graves' disease.N Engl J Med. 2000 Oct 26.
Toft AD. Subclinical hyperthyroidism.N Engl J Med. 2001; 345:512-516.
Woeber K. Update on the managment of hyperthyrodism and hypothyroidism Arch Intern Med. 2000; 160:1067-71.
