Graves' disease

Graves’ disease is hyperthyroidism caused by the immune system jamming the gland’s on-switch in the on position. Instead of waiting for the pituitary’s signal, rogue antibodies push the accelerator themselves, and they never let go.

These antibodies bind and activate the TSH receptor on follicular cells, mimicking thyroid-stimulating hormone but escaping all the normal feedback that would dial production down. The result is a diffusely enlarged, overworking gland and the full picture of hyperthyroidism. Because the immune attack can spill over to tissues behind the eyes, Graves’ disease can also cause bulging, irritated eyes (thyroid eye disease), a feature unique to this cause.

Diagnosis rests on signs of hyperthyroidism plus a positive test for TSH-receptor antibodies or a characteristic high, even uptake of radioactive iodine. Treatment options are antithyroid drugs, radioactive iodine, or surgery, often combined with beta-blockers early on; eye disease may need its own treatment. It is the most common cause of hyperthyroidism, especially in younger women.