Hashimoto thyroiditis is a condition that affects the function of the thyroid, which is a butterfly-shaped gland in the lower neck. The thyroid makes hormones that help regulate a wide variety of critical body functions. For example, thyroid hormones influence growth and development, body temperature, heart rate, menstrual cycles, and weight. Hashimoto thyroiditis is a form of chronic inflammation that can damage the thyroid, reducing its ability to produce hormones.

Hashimoto thyroiditis is thought to result from a combination of genetic and environmental factors. Some of these factors have been identified, but many remain unknown.

Hashimoto thyroiditis affects 1 to 2 percent of people in the United States. It occurs more often in women than in men, which may be related to hormonal factors. The condition is the most common cause of thyroid underactivity (hypothyroidism) in the United States.

The inheritance pattern of Hashimoto thyroiditis is unclear because many genetic and environmental factors appear to be involved. However, the condition can cluster in families, and having a close relative with Hashimoto thyroiditis or another autoimmune disorder likely increases a person's risk of developing the condition.

Published Date: August 01, 2020Published By: National Institutes of Health