Hyperthyroidism

Hyperthyroidism, often referred to as an 'overactive thyroid', is a condition in which the thyroid gland produces and secretes excessive amounts of the free (not protein bound and circulating in the blood) thyroid hormones, triiodothyronine (T3) and/or thyroxine (T4). This is the opposite of hypothyroidism ('sluggish thyroid'), which is the reduced production and secretion of T3 and/or T4. Hyperthyroidism is a type of thyrotoxicosis, a hypermetabolic clinical syndrome which occurs when there are elevated serum levels of T3 and/or T4. Graves disease is the most common form of hyperthyroidism.