The thyroid is a butterfly shaped gland located in the central part of the neck above the collarbone and beneath the larynx. The thyroid produces and releases into the circulation hormones that are involved in regulation of the body’s metabolism and growth.
Thyroid nodules are common in the general population. They can vary in size from a few millimeters across to remarkably large masses the size of a football, and can also vary in content. If these growths are filled with liquid exclusively, they are called thyroid cysts. Fluid filled thyroid cysts are almost always benign. Thyroid tumors are usually solid, but some can contain fluid too and are termed complex cysts. Approximately 90% of thyroid tumors are benign; solitary nodules are more likely to have malignant potential than multiple ones. Risk factors for thyroid cancer include a history of radiation to the head and neck, a family history of thyroid cancer, and certain inherited disorders characterized by the development of multiple tumors.
Many thyroid tumors cause no symptoms. Patients are often unaware of their existe
nce until they are found during a routine exam or on imaging studies such as MRI or CT scans done in the course of evaluation of other illnesses. Many times they will enlarge during pregnancy. Occasionally, however, some thyroid nodules become large enough to produce symptoms that can include:
- Pressure on the trachea, or windpipe
- Jaw, ear, or neck pain
- A visible bulge or swelling at the base of the neck
Typically, thyroid tumors do not affect the production of thyroid hormones unless the tumors become so large that they replace the entire gland. Infrequently, hyperfunctioning thyroid nodules produce an ex
cess amount of thyroid hormone, or thyroxine. This state is characterized by:
- Weight loss
- Rapid heartbeat or palpitations
- Being emotional and irritable
- Thinning hair
- Muscle weakness
- Menstrual irregularities
An enlarged multinodular gland can be associated with an underactive, or hypothyroid state. This condition causes the body’s functions to slow and can be marked by:
- Weight gain
- Slowed heart rate
Evaluation of a thyroid mass involves a careful physical examination, determination of thyroid function blood tests, ultrasound studies of the gland, and nuclear thyroid scans. An ultrasound guided fine needle aspiration biopsy is invaluable in the diagnosis and treatment planning of a potential thyroid cancer.
Treatment is based upon the test results and diagnosis made. In cases where the thyroid nodule is small and benign, the otolaryngologist may follow the mass on ultrasound every 6 to 12 months to assess its behavior. On occasion, treatment for benign thyroid tumors can involve thyroid hormone replacement. In this treatment option, patients are given levothyroxine, a synthetic thyroid hormone, to suppress the growth of the nodule.
Surgical removal of all or most of the thyroid gland for malignant thyroid tumors is usually advised. After such thyroidectomy, the otolaryngologist will recommend lifelong thyroid hormone replacement therapy. Some patients will also take radioactive iodine as a means of eradicating any remaining microscopic thyroid tumor cells that may remain following surgery.