What are thyroid nodules?
Sometimes, people can identify them as a lump in the front of the neck, but often they cannot see or feel them.
The thyroid gland produces thyroid hormones. These hormones have various functions. Organs need them to work properly, and the body needs them to create energy and warmth.
A nodule can develop for different reasons. It may be a cyst, a sign of iodine deficiency, or, in some cases, cancerous.
What are thyroid nodules?
Various problems can lead to thyroid nodules, which may feel like a lump in the throat.
Thyroid nodules are lumps that develop in or around the thyroid gland. A person may have one or more nodules. They are common, affecting an estimated 20 to 76 percent of adults in the United States.
Some nodules are easy to feel, but others may be deep in the thyroid tissue or low in the gland, making them hard to find or detect. In fact, only 4 to 7 percent of thyroid nodules are palpable.
There are different types and forms of nodule, including:
- a thyroid cyst or nodule that is filled with fluid or blood
- a benign nodule, as is usually the case, although some are cancerous
- a nodule that secretes thyroid hormone, although others do not do this
If a nodule produces more thyroid hormone than the body needs, this can lead to complications.
Often, a thyroid nodule has no signs or symptoms. When there are symptoms, these may depend on where the nodule is.
The thyroid gland sits in front of the throat, next to the windpipe and the food pipe. If a nodule presses on the windpipe or food pipe, the person may have:
- a hoarse voice
- a tickling feeling in the throat
- breathing difficulties
- problems with swallowing
- choking sensation when lying flat
- swollen lymph nodes
Rarely, a person may have pain at the site of the nodule that travels to the ear or jaw.
Thyroid nodules can happen for different reasons, as described here:
Iodine is an essential part of the diet. Without it, the body cannot make enough thyroid hormone. When this happens, a goiter, or enlarged thyroid, can develop. Nodules may also form.
The American Thyroid Association recommend that people use iodized salt to prevent iodine deficiency.
Occasionally, a thyroid nodule happens because of an inflammation of the thyroid gland, known as subacute thyroiditis.
This condition is rare, but it can happen after a viral infection such as an upper respiratory virus, the flu, or mumps.
With subacute thyroiditis, the thyroid may be tender or painful, and it may feel bumpy.
Some thyroid nodules produce more of the hormone known as thyroxine. This is one of the hormones that the thyroid gland secretes.
Symptoms can include:
- unintended weight loss
- nervousness and tremor
- fast or irregular heartbeat
- intolerance to heat
Hashimoto's thyroiditis is an autoimmune condition in which the body's immune system attacks the thyroid gland. Scientists do not know why this happens.
Possible risk factors for Hashimoto's thyroiditis include:
- having a family member with thyroid disease
- exposure to radiation
- excessive iodine exposure
Hashimoto's thyroiditis affects women more often than men.
The American Thyroid Association note that more than 90 percent of nodules are benign, but some may be cancerous.
- being female
- being between 25 and 65 years of age
- signs that the nodule has grown
- exposure to any type radiation to the head or neck during childhood
- a family history of thyroid cancer, goiter, or another thyroid disease
- certain genetic conditions
A doctor may suspect cancer if the nodule has the following characteristics:
- a size of at least 4 centimeters
- a firmness when touched
- appears to be fixed to nearby tissues
In 2018, the U.S. National Cancer Institute expect that there will be 53,990 new diagnoses of thyroid cancer, equivalent to 3.1 percent of all cancer diagnoses.
The number of new cases of thyroid cancer is around 14.5 for every 100,000 adults. Roughly 1 percent of these will be fatal.
Other causes of nodules
Other causes of thyroid nodules include:
- a benign overgrowth known as a colloid adenoma, which is usually harmless
- a cyst, which may contain fluid or blood
An ultrasound scan can detect thyroid nodules.
People often cannot see or feel a thyroid nodule. They may learn that they have one when they have an imaging test for another condition.
Tests to investigate unusual thyroid activity include:
- an ultrasound to see if a nodule is present, how big it is, and if it contains fluid
- a blood test to assess hormone levels and other factors
- a biopsy to remove and test a small piece of tissue
- a nuclear thyroid scan
A fine needle biopsy or aspiration can show whether a nodule is malignant or not. The doctor will insert a thin needle into the thyroid gland and suction out a few cells for testing.
If biopsy results suggest cancer, the doctor may recommend surgery to remove the nodule and to examine the tissue more closely.
A nuclear thyroid scan can show whether the thyroid gland is working properly. For this test, the individual takes radioactive iodine by mouth or intravenously. They then undergo a scan to see how well the thyroid gland is working and if there are any nodules.
Treatment for thyroid nodules will depend on their cause.
If a nodule is benign, the doctor will continue to monitor the person closely with physical exams and an ultrasound every few months.
If the nodule is producing hormones, the individual may need medication to regulate these hormone secretions.
If the doctor suspects cancer, they may recommend surgery to remove the cancerous tissue.
They may also suggest surgery if any of the following occur:
- the nodule is large or growing rapidly
- an ultrasound scan reveals a complex cyst
- there are signs of compression of the windpipe or food pipe
Most nodules are not cancerous. Even if cancer is present, the American Thyroid Association note that most are curable, and they rarely become life-threatening.
If a nodule is not cancerous, it may still need treatment, monitoring, or both.