What is the most common cause of hyperthyroidism?

Graves' disease is the most common cause of hyperthyroidism, accounting for a significant portion of cases. This autoimmune disorder leads to the overproduction of thyroid hormones due to stimulation of the thyroid gland by autoantibodies that mimic thyroid-stimulating hormone (TSH). As a result, the thyroid gland becomes hyperactive, producing excess amounts of the hormones thyroxine (T4) and triiodothyronine (T3).

The clinical manifestations of hyperthyroidism typically include symptoms such as weight loss, heat intolerance, increased appetite, anxiety, tremors, and palpitations. In Graves' disease, there may also be specific features such as goiter (enlarged thyroid gland), and potentially eye findings (like exophthalmos) due to the associated orbital disease.

Other conditions causing hyperthyroidism, such as thyroid adenoma, subacute thyroiditis, and Hashimoto's thyroiditis also play roles, but they occur less frequently. Thyroid adenomas can lead to hyperthyroidism but are typically less prevalent compared to Graves' disease. Subacute thyroiditis usually results in transient hyperthyroidism, while Hashimoto's thyroiditis, primarily an autoimmune condition known for leading to hypothyroidism, can