Alternate Names: Endemic goiter

Causes and Risks:

When the thyroid gland is unable to make enough thyroid hormone, it may attempt to compensate by enlarging. Enlargement of an otherwise normal thyroid gland is called colloid nodular goiter.

Colloid nodular goiter often occurs with high frequency in certain geographic areas and is also called endemic goiter. An area is defined as endemic for goiter if more than 10 % of the children aged 6 to 12 years have goiters.

A colloid nodular goiter occurs when the thyroid gland is unable to meet the metabolic demands of the body through sufficient hormone production. The thyroid gland compensates by enlarging which usually overcomes mild deficiencies of thyroid hormone.

Colloid nodular goiters are also known as endemic goiters and are usually caused by inadequate dietary iodine (iodine in diet) and occur in certain geographical areas with iodine depleted soil, usually areas away from the sea coast.

In the U.S., the Great Lakes, Midwest, and Intermountain regions are known as the "goiter belt". The use of iodized table salt prevents this deficiency. The incidence of iodine deficiency is now rare in the U.S. as a result of widespread distribution of foods from iodine sufficient areas.

Risk factors are being a female, over 40 years old, having an inadequate dietary intake of iodine, residence in an endemic area, and a family history of goiters.

Prevention:

Use iodized salt, or foods supplemented with iodine.

Symptoms:

• thyroid enlargement may vary from a single small nodule to massive enlargement
• breathing difficulties from compression of the trachea (rare)
• swallowing difficulties from compression of the esophagus (rare)
• neck vein distention and dizziness when the arms-are raised above the head (large goiter)

Signs and Tests:

• thyroid scan
• thyroid ultrasound
• thyroid stimulating hormone is high or normal
• T4 is low or normal
• radioactive iodine uptake is normal or increased
• urinary excretion of iodine is low

Treatment:

Small doses of iodine (Lugol’s or potassium iodine solution) will treat iodine deficiency. Hormone replacement inhibits the thyroid stimulation hormone and allows for recovery of the thyroid gland.

A large goiter that is unresponsive to medical management or restricts swallowing and breathing may require partial removal of the gland.

Prognosis:

Good with treatment. Colloid nodular goiters may disappear spontaneously, or may become large. In people over 50, a long-standing goiter may become toxic (symptoms of thyroid deficiency develop).

Complications:

• Progressive thyroid enlargement or the development of hardened nodules may indicate thyroid malignancy.
• A simple goiter may progress to a toxic nodular goiter.
• Thyrotoxicosis as a side effect of treatment.

Call your health care provider if signs of thyrotoxicosis develop: increased pulse rate, palpations, diarrhea, nausea, vomiting, sweating, tremors, agitation, or shortness of breath.