Thyroid nodules are solid, painless lumps arising in the thyroid gland; they affect nearly 4 percent of the adult population. Nodules tend to grow slowly over many years. The thyroid gland may contain only one or several nodules. Thyroid nodules are classified according to their production of thyroid hormone: "warm" nodules mimic normal thyroid cells in this regard; "hot" nodules overproduce thyroid hormone and are virtually always benign; "cold" nodules produce little thyroid hormone. Thyroid nodules are usually asymptomatic. "Hot" nodules may produce symptoms of hyperthyroidism. The greatest concern of a thyroid nodule is the possibility of cancer, but only about 5 percent of thyroid nodules are cancerous. Thyroid nodules are often found during a routine physical examination. Imaging studies, such as ultrasound or MRI, can be used to confirm the diagnosis. In addition, a thyroid scan with radioactive iodine or technetium is sometimes used to identify whether the nodule is hot, warm or cold. If the nodule is cold, fine-needle biopsy (removal of a tissue sample, using a small-gauge needle and syringe, for examination under a microscope) is performed to rule out cancer. If a needle biopsy shows no evidence of cancer and thyroid function tests are normal, regular follow-up with thyroid function tests is all that is required. "Hot" nodules may be treated with radioactive iodine or, rarely, surgery. Treatment for hypothyroidism may be needed subsequently if excess thyroid tissue is removed or destroyed by radioactive iodine therapy. If the biopsy confirms or raises suspicions of a malignancy, one or both lobes of the thyroid are surgically removed (thyroidectomy). In the case of cancer, removal of surrounding lymph nodes and other tissues may also be warranted. Radioactive iodine therapy also may be used to destroy thyroid tissue left behind during a thyroidectomy or to treat thyroid cancer that has spread to the lungs or the bones. All patients who have had their thyroid surgically removed require lifetime supplementation with synthetic thyroid hormone. Last Updated: 2/6/2003
The Johns Hopkins University 1996-2003. All rights reserved. This information is not intended to provide advice on personal medical matters, nor is it intended to be a substitute for consultation.
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