Goiter

 Goiter is an common term for any enlargement of the thyroid gland. In some goiters an excess of thyroxine is produced, and in others a reduced amount.

 Nontoxic goiter. In this condition the thyroid gland enlarges in an effort to produce more thyroxine. Because the hormone is in short supply, the pituitary glands stimulates the thyroid to compensate for the deficiency. Factors which provoke this response a shortage of iodine (a constituent of thyroxine) in the food or water; an overuse of thyroid-depressing drugs; and Hashimoto's disease, in which the glandular tissue of the thyroid is destroyed.

Thyrotoxicosis (Graves' disease). The eyes
appear to bulge and are abnormally prominent.

Overactive thyroid (hyperthyroidism)
 A number of forms of overactive thyroid exist; however, the most common problem is overproduction of thyroxine, in spite of a suppression of thyroid-stimulating hormone by the pituitary. Excess thyroxine speeds up all the chemical ( metabolic) activities of the body, affecting both physical and mental functions.
 Graves' disease or thyrotoxicosis occurs eight times more often in women than in men, and is thought to be disturbance in the body's immune system. Less common causes include tumors of the thyroid, pituitary, and placenta. The usual symptoms consist of  nervousness, intolerance to heat, rapid heartbeat, weight loss despite increase appetite, excessive thirst, tiredness, difficult breathing, weakness of the muscles, fine tremor of the hands, frequent urination, and diarrhea.

The thyroid usually enlarges (goiter), and in many cases, the eyes have a ''staring expression'' and appear to bulge (exophthalmic goiter). If the condition remains untreated, the heart may fail through overactivity.
 Toxic nodular goiter usually occurs as a late complication of non-toxic goiter and in most cases develops later in life. The symptoms are less extreme, develop more slowly, and do not include bulging of the eyes. Hearth damage may occur in neglected cases.

what your physician can do. Depending on the severity of the condition, your physician will recommend the most desirable of several methods. A radioiodine scan may help determine the extent of the problem. Antithyroid drugs are used to suppress overactive hormone production, but often the benefit is temporary. The most successful therapy is a single treatment of radioactive iodine, which concentrates in the gland and destroys overactive secreting cells. Many patients become hypothyroid and require replacement hormonal therapy.