Graves' disease is an autoimmune disorder where misplaced attacks from the immune system cause the thyroid gland to become overactive. The result, known as hyperthyroidism, causes the thyroid to produce an excessive amount of the thyroid hormone, thyroxine. Too much thyroxine can affect metabolism, which can then go on to affect brain development, heart and nervous system functions, body temperature, muscle strength, menstrual cycles, weight and cholesterol levels.
Graves' disease is the most common cause of hyperthyroidism in the United States, according to the National Institutes of Health, and it is most often seen in women ages 20 to 40.
The reasons behind the autoimmune attacks are still unclear. Various family and twin studies, including a 2010 epidemiological study of 15,743 Swedish patients hospitalized with Graves' disease, have suggested that the disease has a hereditary component. Moreover, the likelihood of getting the disease is correlated to the number of affected family members. Shared lifestyle among family members seems to explain only a small proportion of familial Graves' disease, according to the study.
Despite that, the same study also found a higher incidence of the disease occurring in both spouses, which suggests that there's a small likelihood that the disease is somewhat influenced by environmental conditions. In addition, the disease is also associated with 19 other autoimmune and related conditions, including Addison's disease, type 1 diabetes mellitus, Hashimoto/hypothyroidism, and lupus erythematosus.
Pregnancy could also trigger Graves' disease. According to the National Women's Health Information Center, as many as 30 percent of young women who get Graves' disease have been pregnant in the 12 months prior to the onset of symptoms.
Diagnosis & Tests
Since hyperthyroidism can manifest itself in the form of goiter, in addition to other symptoms caused by metabolic disruptions, physical examination may find swelling around the neck. Patients could also have an increased heart rate, according to the National Institutes of Health. Some patients could experience Graves' opthalmopathy, where their eyelids retract and eyes budge from their sockets. If Graves' disease is suspected and more tests are merited, the physician could order blood tests and thyroid scans to clarify the diagnosis.
Blood tests measure the level of thyroid-stimulating hormone (TSH) and thyroxine. TSH is produced by the pituitary gland in the brain and normally regulates the level of thyroxine production. In Graves' disease, the autoimmune response creates thyroid-stimulating antibodies, which mimic the function of TSH and overstimulate the thyroid glands into producing more thyroxine than normal. Therefore, patients often have an elevated level of thyroxine even when TSH levels remain normal. The diagnosis can be further confirmed by testing for thyroid-stimulating antibodies in the blood, which would be present in most people with Graves' disease, according to the Mayo Clinic. Patients who have hyperthyroidism caused by other conditions don't have these antibodies.
Thyroid scans use a radioactive iodine tracer to show how and where the iodine is distributed in the thyroid, according to the NIH. The distribution pattern helps to narrow down the type of thyroid disease, since the entire thyroid gland is involved in Graves' disease. Other causes of hyperthyroidism such as nodules — small lumps in the gland — show a different pattern of iodine distribution.
Treatments & Medications
There are three treatment options: radioiodine therapy, antithyroid drugs and thyroid surgery. Radioiodine therapy is the most common treatment for Graves' disease in the United States, according to the National Endocrine and Metabolic Diseases Information Service.
In radioiodine therapy, the patient ingests radioactive iodine-131 pills. Since the thyroid gland collects iodine to make thyroid hormones, the radioactive iodine makes its way to the thyroid gland and slowly destroys thyroid cells, allowing less thyroid hormone to be made. Almost everyone who receives radioiodine therapy eventually develops hypothyroidism (the exact opposite of hyperthyroidism) and must take synthetic thyroid hormone supplements, according to the National Endocrine and Metabolic Diseases Information Service. Radioiodine treatment is not offered to pregnant or breastfeeding women since radioactive iodine can be harmful to the fetus' thyroid and it can pass from mother to child through breast milk.
Two antithyroid medications are available by prescription in the United States: Methimazole (brand name Tapazole) and Propylthiouracil (also known as PTU). Both medications are usually not used for more than one or two years since relapse can be fairly common, according to the Mayo Clinic. In certain cases, patients may opt for a thyroidectomy, or a complete removal of the thyroid gland. As with radioiodine therapy, patients need to take synthetic hormones after the surgery to compensate for the loss of thyroid function. Though risks are rare, surgery could potentially damage the vocal cords and parathyroid glands, which are the tiny glands located near the thyroid gland that produce a hormone that controls calcium levels in the blood, according to the Mayo Clinic.
Although Graves' disease is not preventable, early detection can help patients seek treatment sooner. The American Association of Clinical Endocrinologists suggests regular "neck checks" to check for any bulges or protrusions around the neck when swallowing.