Significant thyroid nodules are solid and larger than 1 cm (about 1/2 inch) in greatest dimension. Thyroid nodules are very common and are not usually cancer. Small nodules may come and go. Generally, nodules over 1-2 cm have about a 20% chance of enlarging over time Some nodules may have both solid and fluid components. These are called complex nodules. Fluid filled nodules are called cyst. Rarely, cystic masses may be malignant. All new thyroid nodules should be evaluated by an experienced physician. From a surgical standpoint, once a thyroid nodule is discovered 3 question should be answered.
- Is it over functioning?
- Is it cancer?
- Is it a source of local symptoms?
Is it over functioning? This is usually answered by checking thyroid function tests. Specifically a TSH (Thyroid Stimulating Hormone) level. Un-expectantly, an elevated TSH level indicates decreased thyroid function. A decreased TSH level indicates elevated thyroid function. If there is evidence of over function, then an I-131 thyroid scan is recommended. If an overactive nodule ( toxic nodule) is found, medical therapy with anti-thyroid medication and possibly radioactive iodine (RAI) is indicated. In selected situations surgery may be appropriate. An overactive nodule is rarely malignant. If the nodule is not over active (hot), then the next two questions become important.
Is it cancer? This question is best answered by a fine needle biopsy (FNA). If the biopsy suggest cancer then surgery is indicated. If it is benign then it may be appropriate to observe the nodule. We will talk about FNA and thyroid cancer in greater detail on other pages. If the nodule is not over active and the FNA indicates it is not cancer, then the third question becomes important.
Is it a source of local symptoms? If the patient is choking or having local discomfort and the symptoms are thought to be due to the compressive effects of the nodule, then surgery may be indicated.
If the answer to all three of these questions is “no” then the nodule can usually be watched. About one third of nodules less than an inch shrink in size. If a nodule increases in size, it may require biopsy again or surgery may need to be considered. There is little evidence to support suppressive therapy with thyroid hormone. Surgery is appropriate if there is a question of cancer, if the nodule is causing local symptoms and in selected cases of an over functioning nodule.