Graves' disease

Definition
Graves' disease, also called diffuse thyrotoxic goiter, is the one of the most common forms of hyperthyroidism. Hyperthyroidism develops when the thyroid gland produces too much of the hormones triiodothyronine (T3) and thyroxine (T4). With Graves' disease, the entire thyroid gland may become enlarged.

Anatomy
The thyroid gland is located in the neck, just below the voice box and on top of the windpipe. This butterfly-shaped gland produces thyroid hormones T3 and T4, which help regulate several body systems, including metabolism and the conversion of calories to energy. The thyroid hormones also help control body temperature, growth and skeletal development, heart rate and function, muscle tone and function, nervous system development, mental function and body weight. When the gland produces too much of the thyroid hormones, your metabolism speeds up.

Causes/associated factors
Graves' disease is considered an autoimmune disorder, a condition in which the body produces antibodies (compounds that help neutralize or destroy foreign substances in the blood) to fight against its own tissues. Rheumatoid arthritis, lupus, pernicious anemia, Addison's disease and a variety of other conditions are also classified as autoimmune diseases. These conditions may run in families, but why they occur is unknown.
Graves' disease tends to run in families and is more common in women. The condition most often occurs between ages 20 and 40, but it can develop at any age. Graves' disease is often triggered by an infection, excess consumption of iodine, drug treatment with lithium, pregnancy, or physical or emotional stress. Often, there is no recognizable cause.


Signs/symptoms
Symptoms typically appear gradually, but sometimes they develop suddenly. Since thyroid hormones affect so many body functions, the symptoms associated with Graves' disease are numerous and may include:
goiter (enlarged thyroid gland)
rapid pulse rate and heart palpitations
hair loss
thinning of skin
nervousness
heat intolerance and excessive sweating
weight loss despite increased appetite
tremors
frequent and/or loose bowel movements
red or inflamed eyes
exophthalmos (protruding or bulging eyeballs)
a grainy feeling in the eyes
blurred or double vision
excess tearing
decreased eye movement
visual sensitivity to light
mood swings
muscle weakness
changes in menstrual cycle
red, thickened and lumpy skin over the shins or tops of the feet
swollen skin around the base of the fingernails
for men, enlarged breasts

Diagnosis
The doctor will review your medical history and do a physical exam. You'll probably need blood tests to measure your thyroxine (T4) levels. Other thyroid hormone studies may measure T3 resin uptake, T3, free T3, free T4 and thyroid stimulating hormone (TSH). Depending on the circumstances, you may need a thyroid scan. With this test, you drink (or take in pill form) a radioactive iodine substance and a picture of your thyroid gland is taken. This test indicates the overall level of thyroid functioning by measuring the amount of iodine the thyroid gland takes from the body. (Because this test may not be done if you're pregnant, doctors often give pregnancy tests to women before doing a radioactive iodine uptake test.) Antithyroid antibodies (antibodies that attack the thyroid gland) may also be measured.

Treatment
The goal of treatment is to decrease thyroid hormone production to normal levels. Treatment options may include medication, radioactive iodine, or surgical removal of part or all of the thyroid gland.
If you're being treated for Graves' disease, keep the following self-care measures in mind:

Do not stop taking prescribed medications or adjust dosages without consulting your doctor.
Get adequate rest.
Eat a well-balanced diet and drink plenty of fluids.
Keep follow-up appointments with your doctor, even if you're feeling well.
Ask your doctor if you need regular checkups with an ophthalmologist for eye care.
Medications
Antithyroid medications such as propylthiouracil (PTU) or methimazole (brand name Tapazole) decrease the amount of thyroid hormone produced, which, in turn, eases the symptoms of Graves' disease. Improvement is usually noticed in about two to four weeks. You may need to take the medication for one to two years, and the condition may resolve completely with no further treatment in about 60 to 70 percent of people. Although rare, propylthiouracil or methimazole can cause agranulocytosis (decreased white blood cells), which may lower your resistance to infection. If you take either of these medications and develop a sore throat, fever or rash, contact your doctor immediately for a white blood cell count.

Your doctor may also prescribe beta-adrenergic blocking drugs such as atenolol or propranolol, which control symptoms by blocking the action of thyroxine in the body. This can help reduce the racing heart, shakes and nervousness. These medications may not be prescribed if you have asthma or other lung problems, however.

Radioactive iodine therapy
Radioactive iodine is given orally, usually as a one-time dose. The thyroid absorbs it from the bloodstream and the radiation destroys part or all of the thyroid gland. Symptoms often improve because the partially destroyed gland can't produce as much hormone. An expected side effect of radioactive iodine is hypothyroidism or underactive thyroid. Hypothyroidism requires long-term thyroid replacement medication. Since hypothyroidism from radioactive iodine therapy may take years to develop, you'll need periodic thyroid testing indefinitely. Exophthalmos may worsen after this type of treatment, particularly if you smoke. If you have exophthalmos, discuss your condition thoroughly with your doctor or ophthalmologist before receiving radioactive iodine therapy. You may need to take steroids before receiving radioactive iodine.

Surgery
Surgical removal of part of the thyroid gland decreases the amount of thyroid hormones produced and released into your bloodstream. Complications of surgery are rare, but may include recurrent hyperthyroidism if not enough thyroid tissue is removed or hypothyroidism if too much thyroid tissue is removed. Injury to nerves in the throat may cause cause hoarseness. Injury to the parathyroid glands (the glands that secrete parathyroid hormone, which regulates calcium and phosphorus metabolism) is also possible.


Complications
When properly treated, complications may include continued hyperthyroidism or a new case of hypothyroidism.
If left untreated, Graves' disease can lead to osteoporosis (bone loss), atrophy (shrinking) of the muscles, paralysis, infertility, eye disorders and heart problems (such as an irregular heart rhythm or congestive heart failure). In some cases, it may be fatal.

If there is a severe and sudden overproduction of thyroid hormones, a thyroid crisis or storm may develop. Physically stressful events such as traumatic surgery, a severe blood infection or other serious illness may bring on this life-threatening condition. If the crisis is not treated immediately, overstimulation of the heart and nervous system may lead to high fever, irregular heartbeat, heart failure, collapse or coma. In some cases, a thyroid crisis may be fatal.


Pregnancy-specific information
Graves' disease may affect your menstrual cycle and cause infertility. Sometimes, childbirth triggers Graves' disease. If you have Graves' disease, make sure your obstetrician and endocrinologist (a doctor who specializes in treating disorders of the endocrine glands, such as the thyroid) work together during your pregnancy to manage your condition.
Graves' disease during pregnancy may increase your risk of certain pregnancy-related complications, including premature delivery, abruptio placenta (early separation of the placenta from the uterus), preeclampsia (pregnancy-induced high blood pressure) or eclampsia (a life-threatening condition for pregnant women and/or fetuses that causes convulsions and/or coma). You are also at a higher risk for congestive heart failure and thyroid storm. Certain medications (such as PTU) may be safely used during pregnancy to treat Graves' disease and reduce the risk of these possible complications. If necessary, surgery may be done during the second trimester.

Because radioactive iodine treatment may damage the thyroid of a developing baby, it's inappropriate for pregnant women. This treatment hasn't been shown to affect fertility or cause birth defects in future children, but waiting at least several months after completing this treatment before attempting to conceive is recommended.


Senior-specific information
If you have an existing heart condition and then develop Graves' disease, the heart condition may become considerably more severe. An irregular heartbeat such as atrial fibrillation may occur, which can increase your risk of stroke. Ask your doctor about the need to consult a cardiologist (a doctor who specializes in treating disorders of the heart) to manage your heart disease.

Prevention
Although Graves' disease is usually not preventable, early diagnosis and treatment can help prevent complications. Discuss testing with your doctor if you're at risk for developing thyroid disease.