Dr. Sheldon Rubenfeld Board Certified in Internal Medicine and in Endocrinology, Diabetes, and Metabolism

Causes of Goiters / Nodules

There are five general causes of thyroid gland enlargement (goiters)

• Growth Factors
• Tumors
• Inflammation / Infection
• Cysts Formation
• Obscure or unknown causes

Three common growth factors cause thyroid gland enlargement. The most common is TSH (thyroid stimulating hormone) from the pituitary gland. When thyroid hormone in the blood is low, the pituitary gland secreted TSH, which stimulates growth of the thyroid gland and release of more thyroid hormone. A second growth factor is an antibody associated with Graves' disease that duplicates the function of TSH. The third growth factor that will cause the thyroid gland to enlarge is human chorionic gonadotropin (HCG). This hormone is produced during pregnancy.

Thyroid Tumors

Thyroid tumors, or growths, occur in 6.4% of females and in 1.6% of males. Most thyroid tumors are benign, but approximately 10% of solitary thyroid nodules are malignant. Multinodular goiters are less likely to be malignant. Although the exact cause of most thyroid tumors is unknown, certain types of radiation will promote their development in both animals and humans.

Inflammation / Infection

Inflammation of the thyroid gland with an accumulation of white blood cells is seen in many types of thyroiditis. The most common type of inflammation and the most common cause of hypothyroidism in the United States is Hashimoto’s thyroiditis. Infection of the thyroid gland, which is very uncommon, also causes white blood cells to accumulate in the thyroid gland. Either inflammation or infection can cause the thyroid gland to enlarge.

Cyst Formation

Cysts are fluid-filled lumps. Thyroid cysts most commonly result from degeneration of benign tissue in a solid nodule, which subsequently liquefies. It is difficult for a doctor to determine from a physical examination whether a thyroid nodule is completely cystic, partially cystic, or solid. Cysts are much less likely to be malignant than are solid nodules. 

Unknown Causes

Sometimes there is no identifiable cause of a goiter or the explanation may be so obscure or uncommon that identifying the cause may be too lengthly or costly to pursue. Identifying the cause of a goiter will not necessarily change the patient's treatment and at the end of the day, the cause of some goiters will remain unknown.