hyperthyroidism

n. condition in which the thyroid gland is overactive

Hyperthyroidism (or "overactive thyroid gland") is the clinical syndrome caused by an excess of circulating free thyroxine (T4) or free triiodothyronine (T3), or both.
See more at Wikipedia.org...

Hyperthyroidism is the overproduction of thyroid hormones by an overactive thyroid. [more]Hyperthyroidism - Community and Resources

Noun
1. an overactive thyroid gland; pathologically excessive production of thyroid hormones or the condition resulting from excessive production of thyroid hormones
(synonym) thyrotoxicosis
(antonym) hypothyroidism
(hypernym) glandular disease, gland disease, glandular disorder, adenosis
(hyponym) Graves' disease, exophthalmic goiter
(part-meronym) exophthalmos

Too much thyroid hormone. Symptoms include weight loss, chest pain, cramps, diarrhea, and nervousness. Also called overactive thyroid.