Thyroid Goiter

What is a Thyroid Goiter?

Definition:
A goiter is an enlargement of the thyroid gland. It is not cancer.

Causes, incidence, and risk factors:
There are different kinds of goiters. A simple goiter usually occurs when the thyroid gland is not able to produce enough thyroid hormone to meet the body's needs. The thyroid gland makes up for this lack by enlarging, which usually overcomes mild deficiencies of thyroid hormone.

A simple goiter may be classified as either an endemic (colloid) goiter or a sporadic (nontoxic) goiter.

Endemic goiters occur within groups of people living in geographical areas with iodine-depleted soil, usually regions away from the sea coast. People in these communities might not get enough iodine in their diet (iodine is vital to the formation of thyroid hormone). The modern use of iodized table salt in the U.S. prevents this deficiency. However, inadequate iodine is still common in central Asia and central Africa.

In most cases of sporadic goiter the cause is unknown. Occasionally, certain medications such as lithium or aminoglutethimide can cause a nontoxic goiter.

Hereditary factors may cause goiters. Risk factors for the development of a goiter include female sex, age over 40 years, inadequate dietary intake of iodine, residence in an endemic area, and a family history of goiter.

Symptoms:

• Thyroid enlargement varying from a single small nodule to massive enlargement (neck lump)
• Breathing difficulties, cough, or wheezing due to compression of the windpipe
• Swallowing difficulties due to compression of the esophagus
• Neck vein distention and dizziness when the arms are raised above the head

Signs and tests:

• Measurement of thyroid stimulating hormone (TSH) and free thyroxine (T4) in the blood
• Thyroid scan and uptake
• Ultrasound of thyroid -- if nodules are present, a biopsy should be done to check for thyroid cancer

Treatment:
A goiter only needs to be treated if it is causing symptoms. The enlarged thyroid can be treated with radioactive iodine to shrink the gland or with surgical removal of part or all of the gland (thyroidectomy). Small doses of iodine (Lugol's or potassium iodine solution) may help when the goiter is due to iodine deficiency.

Support Groups:

Expectations (prognosis):
A goiter is a benign (harmless) process. A simple goiter may disappear on its own, or may become large. Over time, hypothyroidism (not enough thyroid hormone) may develop due to destruction of the normal thyroid tissue. This can be treated with medications to replace the thyroid hormone.

Occasionally, a goiter may progress to a toxic nodular goiter when a nodule is making thyroid hormone on its own. This can cause hyperthyroidism (too much thyroid hormone) and can be treated with radioactive iodine to destroy the nodule.

Complications:

• Progressive thyroid enlargement or the development of hardened nodules may mean thyroid malignancy. All thyroid nodules should be biopsied to check for cancer.
• A simple goiter may progress to a toxic nodular goiter.
• Hypothyroidism may occur after treatment of a large goiter with radioactive iodine or surgery.

Calling your health care provider:
Call your health care provider if you experience any swelling or enlargement in the front of your neck, increased resting pulse rate, or rapid heartbeats. Also call if you have diarrhea, nausea, vomiting, sweating without exercise or increased room temperature, shaking, agitation, shortness of breath, or signs of hypothyroidism such as fatigue, constipation, or dry skin.

Prevention:
The use of iodized table salt prevents endemic goiter.