Hyperthyroidism is the overactivity of the thyroid gland resulting in excessive production of thyroid hormones.
Symptoms are of gradual onset.
Earliest signs may be emotional lability and motor hyperactivity; decline in school performance may also be noted.
Causes are autoimmune (Grave's disease), inappropriate stimulation by trophic factors, passive release of preformed thyroid hormone stores in response to infections, trauma, or other offensive factors inside the body, and extra-thyroidal sources.