One fifth of the world's population (1 billion people) have diets that are deficient in iodine. People in these areas commonly have thyroid enlargement (goiter), and often thyroid nodules as well.
In European countries and many other developed countries iodine intake has only risen to normal levels in recent years. Here in America, many in the population have thyroid enlargement and nodules as a result of iodine deficiency in the past.
In the United States, dietary iodine deficiency was eliminated early in the last century with the addition of iodine to salt and its presence in milk and bread products. And even though dietary iodine is dropping in some parts of the country to borderline and even slightly low levels, goiters here are not due to a lack of iodine.
Therefore if you have an enlargement of your thyroid gland and have not moved to the United States from a country with iodine deficiency, you need to look for another cause for your problem.
The most common cause of goiter here would be a change in thyroid function. If your thyroid begins to fail and hormone levels fall below normal, your pituitary gland senses that there is not enough thyroid hormone in the blood and increases thyroid function and sometimes thyroid size through the action of thyroid stimulating hormone, which it releases into the bloodstream. If your thyroid gland becomes overactive, antibodies stimulate the gland to overproduce thyroid hormone and often enlarge the gland as well.
Subacute thyroiditis can also result in a larger and sometimes tender thyroid.
If none of these are your problem, your doctor will examine you to be sure that your thyroid is not enlarged due to the presence of a nodule, which are usually benign but occasionally malignant.
The treatment of a goiter will depend on the cause. Usually if it's due to the thyroid becoming overactive or underactive, correction of the underlying condition will prevent further growth and often result in a return to normal or near normal size. If the gland is so large as to be cosmetically disfiguring, it may be removed surgically. This is often done if a thyroid has been markedly enlarged for years, in which case an enlarged thyroid may not shrink very much no matter what the treatment. If that is your situation, our best advice is to choose your surgeon well, for an experienced thyroid surgeon lowers your risk for complications, particularly damage to the vocal cord nerves or parathyroid glands. Choosing a thyroid surgeon is important and discussed in more detail elsewhere on this website under Find a Doctor. Occasionally a thyroid gland will enlarge due to the presence of a lymphoma or other tumor within the gland. Treatment will depend on the nature of the tumor and for this you'll often need to see an oncologist as well as a thyroid specialist, and usually a thyroid surgeon.
Sometimes a benign nodule or goiter may decrease in size with thyroid hormone or radioactive iodine treatment. These situations are very individual, and it's best to see a thyroid specialist who is up to date with current research and is in the best position to know what's best for you.
More common in women than men, it affects about 3.2% of women and 0.32% of men in the United States.