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How does Graves disease cause excess thyroid hormone production?

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immune system disorder False-color scanning electron micrograph of a T cell infected with HIV (human immunodeficiency virus), the agent that causes AIDS (acquired immunodeficiency syndrome).

Graves disease causes excess thyroid hormone production through an autoimmune process involving the development of specific antibodies.12

In a healthy system, the production of thyroid hormones is regulated by thyroid-stimulating hormone (TSH), which binds to TSH receptors on thyroid cells to trigger hormone secretion. In patients with Graves disease, the immune system produces antibodies that target these same TSH receptors. These antibodies act as mimics, binding to the receptors and continuously stimulating the thyroid cells.13

Because these antibodies bypass the body's normal regulatory signals, they cause the thyroid gland to produce and secrete excessive amounts of thyroid hormones, leading to hyperthyroidism. This persistent stimulation often results in a diffuse enlargement of the thyroid gland, known as a goiter.123