What Is Hyperthyroidism?
Hyperthyroidism occurs when you have an overactive thyroid gland. The result of this excess activity is called thyrotoxicosis, which means that you have too much thyroid hormone circulating in your blood.
Hyperthyroidism is much less common than hypothyroidism. According to the AACE, the condition occurs in almost 1 percent of the U.S. population. Women are affected five to ten times more often than men are.
The cause of hyperthyroidism varies among patients, but identifying the cause is essential to figuring out your treatment. The most common culprit is Graves' disease, an autoimmune condition that we'll discuss in greater detail in another chapter. In Graves' disease, autoantibodies attack the thyroid gland, causing it to release excess amounts of thyroid hormone.
Some people develop hyperthyroidism as the result of toxic multinodular goiter. This condition is most common in adults over the age of sixty, who have been living with an undetected goiter for a long time. In that time, the goiter develops nodules that begin to churn out a supply of thyroid hormone on their own, without any prodding from the pituitary gland.
Many patients who have hyperthyroidism develop hypothyroidism after treatment. In some cases, the diseased gland is destroyed intentionally, knowing that the patient will go into a hypothyroid state. But remember, hypothyroidism is easily treated with thyroid replacement hormone. It's much better to be hypothyroid than hyperthyroid.
Hyperthyroidism may also be the result of a single toxic nodule, a condition called Plummer's disease, which was named after Henry Stanley Plummer, an American doctor. Another name for this condition is single hot nodule, or toxic adenoma. Like toxic multinodular goiter, this single nodule will produce more thyroid hormone than your body needs, causing you to become hyperthyroid.
Some people may develop hyperthyroidism as a result of sub-acute thyroiditis, in which the thyroid gland becomes enlarged, inflamed, and painful. The result of this enlargement is the release of too much thyroid hormone.
Who is at risk for hyperthyroidism?
Being a woman increases your odds for hyperthyroidism — especially if you're pregnant. The condition is also more common in people between the ages of 30 and 50. In addition, your risk goes up if you have a family or personal history of thyroid problems. People who have an autoimmune disease such as lupus, rheumatoid arthritis, or type 1 diabetes are more likely to get Graves' disease, a type of hyperthyroidism, as well.
In other cases, the hyperthyroidism is the result of silent thyroiditis, in which the thyroid gland becomes painlessly inflamed. After giving birth, about 5 to 10 percent of women may develop a form of this condition called postpartum thyroiditis. In both silent and postpartum thyroiditis, the thyroid may remain overactive for one to two months, followed by several months of hypothyroidism. Eventually, normal thyroid function resumes, though some people become permanently hypothyroid.
Some cases of hyperthyroidism result from eating too much iodine, the mineral the thyroid uses to produce thyroid hormone. Experts call this iodine-induced hyperthyroidism. It may occur in people who take certain medications such as amiodarone, which is used to treat abnormal heart rhythms. It may also occur in people who take kelp, a type of seaweed that has been touted as a health supplement for numerous ailments.
Finally, some people can develop hyperthyroidism when they are being treated for hypothyroidism. This type of hyperthyroidism may occur when the dose of thyroid hormone replacement is too high. It is usually corrected once the dosage is properly adjusted.