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Thyroid Nodules

Hyperthyroidism and Thyroid Cancer

Thyroid nodules are lumps that commonly arise within an otherwise normal thyroid gland. Most commonly, these abnormal growths of thyroid tissue do not produce any symptoms whatsoever.  Thyroid nodules are usually found during a routine examination of the neck by a health care provider, or from X-ray studies obtained for other reasons. 

When thyroid nodules do produce symptoms it is either due to their larger size or their location within the gland. Thyroid nodules which are located at the edge of the thyroid gland can sometimes be felt as a lump in the throat or even seen as a lump in the neck when they occur in very thin individuals.

The following is a list of facts regarding thyroid nodules: 

  •  Thyroid nodules are three times more common in women than in men
  •  30% of 30-year-old women will have a thyroid nodule.
  •  One in 40 young men has a thyroid nodule.
  •  More than 95% of all thyroid nodules are benign (non-cancerous growths).
  • Some thyroid nodules are actually cysts, which are filled with fluid rather than thyroid tissue.
  • Purely cystic thyroid nodules (thyroid cysts) are almost always benign.
  • Most women will develop a thyroid nodule by the time they are 50 years old.
  • The incidence of thyroid nodules increases with age.
  •  50% of 50-year-old women will have at least one thyroid nodule.
  •  60% of 60-year-old women will have at least one thyroid nodule.
  • 70% of 70-year-old women will have at least one thyroid nodule.

 Four Questions about Thyroid Nodules

  • Is the nodule one of the few that are cancerous?
  • Is the nodule causing trouble by pressing on other structures in the neck?
  • Is the nodule making too much thyroid hormone?
  • Do I need to do anything about my thyroid nodule?

After an appropriate work-up, most thyroid nodules will yield an answer of no to all of the above questions. In this most common situation, there is usually a small- to moderate-sized nodule that is simply an overgrowth of normal thyroid tissue. Even when thyroid nodules are quite large, thyroid function is most commonly totally normal.

Patients with multiple thyroid nodules in a diffusely enlarged thyroid (called a goiter or multinodular goiter) will have what is perceived at first to be a nodule but is later found to be only one of many benign enlarged growths within the thyroid (a goiter).

There are three tests that may be considered in any patient with a thyroid nodule.  The first is a blood test in order to determine how much thyroid hormone is being produced.  Thyroid nodules rarely produce too much thyroid hormone.  But when excessive thyroid hormone is being produced by the thyroid nodule this is almost always associated with a benign (non-cancerous) nodule. Benign thyroid nodules that produce extra thyroid hormone are usually removed to cure the excessive hormone production.

The second test considered in the evaluation of a thyroid nodule is an ultrasound. Ultrasound of the thyroid must include the analysis of lymph nodes of the neck, as well.  Because thyroid cancers can frequently spread to neck lymph nodes, the ultrasound analysis of the neck lymph nodes can provide important information about an unknown thyroid cancer sometimes far superior than the ultrasound of the thyroid itself.

The quality of the thyroid ultrasound is dependent upon several factors.  Each of these factors plays an important role in determining the quality of the thyroid ultrasound.  Any one factor that limits the ultrasound can decrease the quality of the information available by the ultrasound.  The ultrasound is necessary to determine the characteristics of the thyroid nodule and the neck lymph nodes in determining the risk for thyroid cancer.

Thyroid Ultrasound Critical Factors

The quality of a thyroid ultrasound is dependent upon four critical individual parts. All of these parts are required to be of the highest quality otherwise the ultimate sensitivity and accuracy of the diagnostic thyroid ultrasound can be lost.

The factors that are critical to assure diagnostic accuracy are:

  • Proper calibration for thyroid evaluation of the ultrasound machine.
  • Use of the transducer transmitting and receiving ultrasound waves.
  • Training and experience of ultrasound technician specific to the thyroid 
  •  A radiologist with specialized training in thyroid imaging to interpret the ultrasound study findings.

For thyroid nodules that are greater than 1 cm (one half an inch) in size, a fine needle aspiration biopsy (FNA) is frequently considered.  Smaller thyroid nodules are generally not biopsied unless other concerning findings are noted. 

Pathologists that are expert at looking at thyroid cells under a microscope, called thyroid cytopathologists, can commonly determine whether a nodule is benign or cancerous. When the thyroid cytopathologist diagnosis falls somewhere in between a benign and malignant determination, today, several commercially available genetic studies of the FNA material can be considered to help patients and doctors determine the relative risk of thyroid cancer. 

Medical or surgical treatment of a thyroid nodule may be considered when:

  • The thyroid nodule is cancerous.
  • The thyroid nodule is producing too much thyroid hormone.
  • The thyroid nodule is causing disruptive symptoms.

Symptoms of Thyroid Nodules

Thyroid nodules most commonly cause no symptoms at all. In this light, thyroid nodules are most commonly found by routine neck examinations by health care providers or due to x-ray studies obtained for other reasons. Thyroid nodules which are found because the patient is undergoing a CT scan, MRI scan, or ultrasound scan of the neck for some other reason (such as parathyroid disease, trauma, carotid artery disease, or cervical spine pain).

When thyroid nodules are found accidentally, they are cancerous even less than 1% of the time. A more sophisticated type of imaging x-ray called a PET/CT scan is being used to screen for other types of cancers.  Unlike other x-ray studies, thyroid nodules found on PET/CT scans may be diagnosed as cancerous in 50% of cases.

When thyroid nodules do produce symptoms, the most common of these symptoms is a lump in the neck followed by a sense of mass while swallowing.

Very rarely, nodules may cause pain or discomfort.  True complaints of difficulty swallowing when a nodule is large enough and positioned in such a way that it impedes the normal passage of food through the esophagus (which lies behind the trachea and thyroid) is even more rare.

What to Do if You Have a Nodule

Remember, the vast majority of thyroid nodules are benign. The nodule should be evaluated by a physician who is comfortable with this problem. Endocrinologists and thyroid specialist surgeons deal with these problems on a regular basis, but many family practice physicians, general internists, and general surgeons and otolaryngologists (ENT surgeons) are also adept at addressing thyroid nodules.

One of the first things a physician should do is ask two important questions regarding your health and potential thyroid problems. The first question is whether you have been exposed to nuclear radiation or received radiation treatments as a child or teenager.  The second question is whether there is a family history of thyroid cancer or other endocrine conditions.

What about Radiation Exposure?

Ionizing radiation has been known for a number of years to be associated with a small increased risk of developing thyroid cancer. The risk is very small and the amount of radiation exposure is higher than that produced by the routine use of x-rays. There is typically a delay of 5 years or more between radiation exposure and the development of thyroid cancer.

Radiation was used occasionally between the 1920s and 1950s to treat certain head and neck conditions, such as enlarged tonsils, certain skin conditions (such as severe acne), and sinusitis.

Testing for the possibility of thyroid cancer developing from exposure to radiation has been done in the United States. These epidemiological studies determined that nuclear tests would likely increase the number of thyroid cancers seen in Americans over future decades.

However, the risks are greatest for those patients living near test sites for many years. If there is any good news from this report, it is that these cancers will typically be of the well-differentiated papillary thyroid cancer, the type that has an excellent prognosis with a very high cure rate. Despite these increased risks, thyroid cancer is still relatively uncommon and usually very curable.

Inherited types of thyroid cancer are very uncommon. The one type of thyroid cancer that may have a higher genetic link, by far, is called medullary thyroid cancer. Approximately only 3% of all thyroid cancers are medullary thyroid cancer and of these, less than one half are inherited. 

Benign Thyroid Nodules Treatment

Observation (Most Common)

If the thyroid nodule biopsy suggests that it is benign, simply watching the patient and the thyroid nodule is often most appropriate. The duration of active observation is somewhat arbitrary. Observation (or surveillance) usually means repeating thyroid blood tests, ultrasound, and physical examination in approximately one year. If the thyroid nodule should increase in size or produce symptoms, a repeat biopsy or another intervention may be indicated. Thyroid nodules that don’t change over a period of years likely will never require any treatment whatsoever.

Thyroid Hormone Therapy

Although there is little to no evidence to support that taking thyroid hormone effects the growth of benign thyroid nodules, the practice of prescribing thyroid hormone for benign thyroid nodules continues. In theory, prescribing thyroid hormone can lower the thyroid stimulating hormone (TSH) production of the pituitary gland and thus decrease the stimulation of thyroid tissue growth.

Surgery

Sometimes clearly benign thyroid nodules are managed with surgery. Some potential reasons for removing benign thyroid nodules include:

  • Large size (producing a visible mass in the neck)
  • Producing symptoms such as pressure or discomfort on the breathing tube or swallowing tube (esophagus). 
  • Producing excessive or high levels of thyroid hormone.
  • indeterminate or suspicious signs of cancer on FNA biospy.
  • Multinodular goiters producing symptoms

Malignant Thyroid Nodules (Cancer) Treatment

Almost all thyroid nodules that are malignant are treated by surgery. The options regarding the extent of thyroid surgery including total removal of the thyroid gland (total thyroidectomy) versus removal of half of the thyroid gland (thyroid lobectomy). 

You can read more about total thyroidectomy and thyroid lobectomy. Only expert thyroid cancer surgeons should be performing thyroid surgery because the risk to the patients including the nerves to the voice box and glands that control calcium are significantly higher in those that do not do these types of surgery routinely and frequently.

We'd like to thank James Norman, MD, for his original contributions to this content.

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