thyrotoxicosis Over‐activity of the thyroid gland, leading to excessive secretion of thyroid hormones and resulting in increased basal metabolic rate. Hyperthyroid subjects are lean and have tense nervous activity.

Iodine‐induced thyrotoxicosis affects mostly older people who have lived for a long time in iodine‐deficient areas, have had a long‐standing goitre, and then have been given extra iodine. Also known as Jodbasedow, or Basedow's disease.

thyrotoxicosis (th'y-roh-toks-i-koh-sis) n. the syndrome due to excessive amounts of thyroid hormones in the bloodstream, causing a rapid heartbeat, sweating, tremor, anxiety, increased appetite, loss of weight, and intolerance of heat. Causes include simple overactivity of the gland, a hormone-secreting tumour, and Graves' disease (exophthalmic goitre), in which there are additional symptoms including swelling of the neck (goitre) and protrusion of the eyes (exophthalmos).
—thyrotoxic (th'y-roh-toks-ik) adj.