Autoimmune thyroid disease may cause symptoms even when hormone levels are normal

Hashimoto's thyroiditis, an autoimmune disease that often causes hypothyroidism, may lead to negative health effects even when levels of thyroid hormone are normal, according to recent research.

Endocrinologists and surgeons at the Medical University of Vienna found that the thyroid disease can reduce quality of life even when its main side effect - hypothyroidism - is not present. Their results appear in a study published in the journal Thyroid.

Hashimoto's thyroiditis is a disorder in which the body's immune cells attack and slowly destroy thyroid tissue. The condition affects approximately 14 million Americans, though it is seven times more likely to be diagnosed in women, the American Association of Clinical Endocrinologists (AACE) reports.



As antibodies attack thyroid cells, the thyroid gland itself becomes inflamed and under-active. Over time, this gradual degradation of thyroid tissue causes swelling of the gland and underproduction of thyroid hormone.



Symptoms of the disease include those of hypothyroidism - fatigue, dry or itchy skin, brittle hair, soreness, weight gain and heavy menstrual flow among women.

In the new study, researchers noted the symptom levels of more than 400 women with thyroid conditions, including Hashimoto's thyroiditis. They theorized that higher levels of antithyroperoxidase antibody - an immune cell associated with Hashimoto's - would correspond with more severe symptoms.

While this was found to be the case, the team made an unexpected secondary discovery. Women with Hashimoto's thyroiditis often experienced its symptoms even when their levels of thyroid hormone were within a healthy range.

The study's authors concluded that hypothyroidism is only partly to blame for the increase in side effects and decrease in quality of life caused by Hashimoto's thyroiditis.

Hypothyroidism is most common in women over 50, individuals with an autoimmune disease and those who have been given radiation or radioactive iodine therapies, according to the Mayo Clinic.
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