GRAVES' DISEASE

also called toxic diffuse goitre, or exophthalmic goitre endocrine disorder that is the most common type of hyperthyroidism, or thyrotoxicosis (oversecretion of thyroid hormone). In Graves' disease the excessive secretion of thyroid hormone is usually accompanied by diffuse primary overgrowth of the thyroid gland (which results in goitre) and by exophthalmos (protrusion of the eyeballs), with eyelid retraction and other eye signs. The thyroid gland may be enlarged from twice to several times its normal size. The increased levels of thyroid hormone result in increased cardiac output with tachycardia (rapid heartbeat), palpitations, possible shortness of breath, fibrillation (rapid, irregular contractions of the heart muscle), and heart failure. Nervousness, hyperexcitability, restlessness, insomnia, and emotional instability are not unusual, nor are such symptoms as weight loss, muscular weakness and wasting, and diarrhea. Physical or emotional stress may precipitate a crisis known as "thyroid storm," which may result in vasomotor collapse and, if untreated, in death. Graves' disease is considered to be an autoimmune disease (i.e., one in which the body reacts defensively to its own tissues or fluids as though they were foreign substances introduced into the body). An antibody with thyroid-stimulating properties has been isolated from the blood serum of many Graves' patients. Graves' disease occurs in women four times as often as in men, has a tendency to affect young to middle-aged adults, and demonstrates a familial pattern. Treatment of severe cases entails the surgical removal of all or part of the thyroid gland. Sometimes the condition can be controlled by the oral administration of radioactive iodine, iodide, or certain of the enzyme-blocking agents such as thiouracil. Therapeutically administered radioactive iodine is taken up by the cells of the thyroid gland just as is nonradioactive iodine in the course of the synthesis and secretion of thyroid hormone. When present in sufficient dosage, however, radioactive iodine results in the destruction of the thyroid's cells. The dosage can be regulated so that sufficient undamaged tissue remains to maintain normal thyroid function in most cases. Although many of the abnormalities produced by Graves' disease can thus be corrected, some of the eye changes produced by it may be permanent.