Hashimoto's disease is the most common cause of hypothyroidism in the United States and affects approximately 14 million Americans. It is also the most common cause of goiter in this country. The disease occurs most frequently in women between the ages of thirty and fifty.

Hashimo to's disease is also called chronic lymphocytic thyroiditis because of the lymphocytes — disease-fighting white blood cells — that are found in the thyroid tissue. The disease is characterized by inflammation of the thyroid gland. In many cases, people who have Hashimoto's will go on to develop hypothyroidism.

Causes

No one knows exactly what causes the body's immune system to turn against itself in Hashimoto's — or any other autoimmune disorder for that matter. Like most other autoimmune conditions, Hashimoto's tends to run in families. You might have a mother who has type I diabetes, an aunt who has lupus, and a sister who has Hashimoto's.

Because autoimmune problems are much more prevalent in women, some experts think that hormones somehow play a role in the disease process. But as of now, no one knows for sure how reproductive hormones might promote autoimmune disorders.

Some experts suspect that environmental factors are at play, too. Stress, viruses, infections, pollution, bacteria, and other influences may spur on the development of autoimmune disease. But again, these are theories, and the exact cause of any autoimmune disease remains a mystery. Most researchers believe that it's a combination of genetics and environmental factors that cause Hashimoto's.

Symptoms

Initially, many people with Hashimoto's have no symptoms at all. But over time, they may develop a goiter. Some patients may notice the goiter as a painless swelling at the base of their neck. Sometimes, this swelling can make it difficult to swallow or breathe.

After a while, as more thyroid tissue is destroyed, you may develop symptoms of hypothyroidism. Not everyone with Hashimoto's or the anti-TPOs gets hypothyroidism, but if you do, you may notice that you are more tired than usual, and that you're frequently forgetful. You may be especially sensitive to the cold, and your skin, nails, and hair may become dry. If you are a woman, your menstrual periods may become heavier and more painful. And if you're trying to get pregnant, you may suffer recurrent miscarriages.

Less commonly, Hashimoto's may initially trigger hyperthyroidism, a condition sometimes called Hashitoxicosis. As the thyroid cells are destroyed, large amounts of stored thyroid hormone are released into the bloodstream, causing a rapid heartbeat and feelings of anxiety and nervousness. Then, as the hormone dissipates, your body returns to normal functioning for a while, before going into a state of hypothyroidism when the thyroid isn't able to produce enough thyroid hormone. Gloria remembers how her hypothyroidism began with a bout of hyperthyroidism:

Gloria was in her thirties when she started having severe pain in her lower neck. She was rapidly losing weight and having bouts of crying for no apparent reason. She didn't feel like herself and felt so out of control that she went to see a psychiatrist, who referred her to an endocrinologist. The doctor found hot nodules — the kind that take up RAI — which indicated an overactive thyroid gland. But over time, the nodules turned cold, and eventually, she was deficient in thyroid hormone and put on Synthroid. Thirty years later, she is still taking Synthroid and has her thyroid checked every year.