Thyroid nodules are very common and usually are asymptomatic. Thyroid nodules are abnormal growths in the thyroid gland that may be felt as a lump in the throat.
Because the majority of these nodules are benign (more than 95%) the evaluation and treatment of thyroid nodules is usually conservative.
Thyroid Nodule In Depth
by Monica Tadros, M.D., F.A.C.S.
It may be difficult to distinguish cancerous growths from the many benign lumps in the thyroid gland. A number of risk factors are used to evaluate the possibility of malignancy in a thyroid nodule. In patients with a diffusely enlarged thyroid (called a goiter), multiple small nodules are usually benign. In patients with a single solitary nodule, more rigorous evaluation is warranted.
What risk factors are concerning in Thyroid Nodule evaluation?
- Male gender: Males tend to have fewer thyroid nodules than females and more often have solitary nodules.
- Age less than 30 years old or greater than 55 years old is more concerning.
- Single Nodules of Large Size: Solitary nodules greater than 1cm are usually evaluated for the possibility of malignancy. A solitary nodule greater than 2cm may be concerning.
- Family history of thyroid malignancy may be concerning.
- History of Radiation Exposure: The transformation of benign nodules to malignancy is more common in patients who have had exposure of the thyroid gland to radiation. A delay of 20 years or more between exposure and transformation is common.
- Compressive symptoms: Patients with large nodules may experience pressure on the esophagus causing difficulty swallowing (dysphagia) or pressure on the voice box (larynx) or windpipe (trachea). Voice changes or persistent hoarseness may be an ominous sign indicating compression of the recurrent laryngeal nerve. An evaluation by an otolaryngologist to check the vocal cords is important for comprehensive evaluation.
- Thyroid hormone imbalance: There is no association between thyroid hormone imbalance and risk of malignancy. However, abnormal thyroid hormone blood levels should be treated. In hypothyroid states, treatment with thyroid hormone replacement may improve symptoms and suppress the growth of nodules. This is called thyroid hormone suppression.
How are thyroid nodules best evaluated?
An ultrasound-guided fine needle aspiration (FNA) is extremely helpful in determining the nature of a thyroid nodule. The ultrasound can help determine the size and nature (solid, cystic, or both) of the nodule. Cytology (cellular characteristics) of the aspirated material can usually help profile the nodule and determine the relative risk of malignancy.
Are there any limitations to fine needle aspiration (FNA)?
There have been many advances in the cellular evaluation of the aspirate obtained from FNA. The use of ultrasound or is some cases CT, helps ensure that an adequate specimen was obtained. The pitfalls of this technique are operator dependent. The results are dependable if the doctor is confident the solid component of the nodule was needled and enough cellular material was obtained. Also, the FNA can only provide information about the nodule tested. If there are multiple nodules in question, a single nodule FNA may miss pathology in neighboring nodules.
What do I do if I Have a Thyroid Nodule:
The vast majority of thyroid nodules are benign so don’t be alarmed. An experienced physician comfortable in treating thyroid disease should evaluate all thyroid nodules. Workup at a minimum should include thyroid blood tests (TSH and free T4) and a thyroid ultrasound. Endocrinologists or head and neck surgeons should be consulted on the treatment of patients with risk factors and solitary nodules greater than 1cm and an FNA recommended. Treatment depends on the results of evaluation and may range from routine surveillance with ultrasound, to thyroid hormone suppression, to thyroid removal. Most thyroid malignancies are curable with thyroid removal and/or radioactive iodine therapy.