Thyroid stimulators in health and disease

Thyroid function in health is largely controlled by thyroid-stimulating hormone (TSH) produced by the thyrotroph cells of the anterior pituitary. Alterations of intrathyroidal iodine content may also be involved in autoregulation by the thyroid, particularly in states of iodine deficiency and excess (Ingbar, 1972). During pregnancy placental thyroid-stimulating agents-human chorionic thyrotrophin (HCT) and human molar thyrotrophin (HMT)-are produced. In the common variety of hyperthyroidism, Graves' disease, thyroid function appears to be regulated by thyroid-stimulating immunoglobulins (TSI) (Smith & Hall, 1974a). Human molar thyrotrophin can be produced by trophoblastic tumours in both sexes and thyroid-stimulating factors have been reported to be released by malignant tumours of the gut and by bronchogenic carcinomas, although this is one of the rarest of the ectopic hormone syndromes.