APA Dictionary of Psychology

n. a condition caused by an excess of thyroid hormones, which may be produced by an overactive thyroid gland or administered therapeutically. Endogenous thyrotoxicosis may be familial and can involve an autoimmune reaction in which the patient’s antibodies stimulate rather than destroy the cells producing thyroid hormone. Thyrotoxicosis is characterized by nervousness, tremor, palpitation, weakness, heat sensitivity with sweating, and increased appetite with weight loss. There may be exophthalmos associated with goiter. Thyrotoxicosis is frequently associated with hyperplasia (enlargement) of the thyroid gland, as in Graves’ disease, or the development of thyroid nodules (Plummer’s disease), which occurs in older people. See also hyperthyroidism.