Thyroid nodules are lumps that can appear in the thyroid gland in the front of the throat. Thyroid nodules may not cause any symptoms, but people may sometimes feel a bump in the neck. Most are harmless, but some can be cancerous and require treatment.
Thyroid nodules develop when thyroid cells build up in the thyroid gland. Some people will discover a cyst by feeling it in their neck; however, most people will not know they have a thyroid nodule until a doctor identifies it.
The thyroid gland produces hormones with various functions, including helping the organs to work properly and to create energy to keep the body warm. In some cases, a thyroid nodule may disrupt the normal production of thyroid hormones.
A nodule can develop for different reasons. It may be a cyst or, less commonly, cancerous.
This article looks at the possible causes and types of thyroid nodules, symptoms, diagnosis, and treatment.
What are thyroid nodules?
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Thyroid nodules are lumps that develop in or around the thyroid gland. A person may have one or more nodules. Thyroid nodules are common in the United States, affecting an estimated 50% of adults by 60 years of age.
Some nodules are easy to feel, but a person may not feel those smaller than 1 centimeter (cm) or located deep in the thyroid gland.
Nodules can be cystic or solid. One type of solid nodule is a colloid nodule that develops due to a build-up of thyroid cells and is not harmful; cancerous thyroid cells are another type of solid nodule.
Other nodules are functional or autonomous, which means they can produce thyroid hormones, while others are not.
If a nodule affects thyroid hormone production, it can cause symptoms of hypothyroidism or hyperthyroidism. One example of this is toxic multinodular goiter, which occurs when nodules that grow in the thyroid gland affect the thyroid hormone.
Symptoms
In most cases, a thyroid nodule has no signs or symptoms. If symptoms are present, they may include:
- pain in the neck
- difficulty swallowing
- hoarse voice
- swelling in the neck
- unexplained weight gain or sudden and rapid weight loss
- irregular or increased pulse
- anxiety or feeling nervous
- intolerance to cold
- fatigue
- dry skin
- swelling in the face
Symptoms may also depend on the size of the nodule. 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:
- problems with swallowing
- a tickling feeling in the throat
- breathing difficulties
In rare cases, a person may have pain at the nodule site that travels to the ear or jaw.
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Treatment
Treatment for thyroid nodules will depend on their type and cause.
If a doctor has declared a nodule benign from tests, they will monitor the person closely with physical exams and an ultrasound every 6–12 months.
If large nodules are causing swallowing or breathing difficulties or affecting thyroid hormones, people may require surgery to remove the nodule.
If doctors suspect a thyroid nodule is cancerous, people may have surgery and radioactive iodine therapy to remove the thyroid gland and destroy any harmful cells.
Surgery
People may require surgery if a nodule is:
- too large
- hyperfunctioning
- causing difficulties with breathing or swallowing
- cancerous
- difficult to distinguish as benign
In some cases, a surgeon may remove the entire thyroid gland. Some people may have a scarless thyroid procedure, where a surgeon will make an incision from the inside of the lower lip to operate on the thyroid. Some people may choose to have a neck incision instead.
Radiofrequency ablation
Some people with benign thyroid nodules may undergo a procedure called radiofrequency ablation. This involves doctors using a probe and an ultrasound scan to shrink the nodule with an electrical current.
Most people recover from this procedure quickly and are back to their usual activity level the following day.
Causes
The cause of thyroid nodules is unknown. However, a range of possible causes includes:
Iodine deficiency
According to the American Thyroid Association (ATA), iodine is an essential part of the diet. Without it, the body cannot make enough thyroid hormone. If a person is iodine deficient, a goiter, or enlarged thyroid, can develop. Nodules may also form. Iodine deficiency is very uncommon in the U.S.
The ATA recommends that people use iodized salt to prevent iodine deficiency. People may also need to take an iodine supplement during pregnancy.
An iodine deficiency may also lead to toxic thyroid nodules, which are nodules that lead to an excess of thyroid hormones, resulting in hyperthyroidism. Toxic thyroid nodules can cause symptoms such as:
- unintended weight loss
- tremor
- fast or irregular heartbeat
- intolerance to heat
- increased sweating
- tiredness
- irritability
- diarrhea
Hashimoto’s thyroiditis
Hashimoto’s thyroiditis is an autoimmune condition in which the body’s immune system attacks the thyroid gland. Hashimoto’s thyroiditis increases the risk of thyroid nodules.
Possible risk factors for Hashimoto’s thyroiditis include:
- having a family member with thyroid disease
- being between the ages of 40–60 years, although the condition can also affect younger people
- being female
- having an existing autoimmune condition, such as rheumatoid arthritis or type 1 diabetes
Cancer
The ATA notes that more than 90% of nodules are benign, but some may be cancerous.
There are many different types of thyroid cancer, each with different treatment options and outlooks. Risk factors for thyroid cancer include:
- being female
- being between 25 and 65 years of age
- being Asian
- exposure to any type of radiation to the head or neck during childhood
- a family history of thyroid cancer, goiter, or another thyroid disease
- certain genetic conditions, such as familial medullary thyroid cancer
Thyroid cancer may not cause any signs or symptoms to start with, but if a tumor grows larger, it could cause:
- difficulty breathing
- difficulty or pain when swallowing
- hoarse voice
People experiencing any of these symptoms should check with a doctor to find the underlying cause.
When to biopsy
Doctors cannot usually tell if a thyroid nodule is cancerous just through a physical examination and blood tests. This means that a doctor may often decide to carry out a nodule biopsy using a fine needle biopsy procedure.
A fine needle biopsy will usually take place in a doctor’s office. During a fine needle biopsy, a doctor will use a tiny needle to extract several cell samples from within the thyroid nodule. A laboratory will then examine the cells under a microscope to determine if the nodule is benign.
Are they cancerous?
Most thyroid nodules are not cancerous. In 80% of thyroid nodule biopsies, the result is benign. This means the nodule is non-cancerous, and a doctor will not need to remove the nodule unless it is causing symptoms, such as difficulty breathing or swallowing.
However, it is not always possible to detect cancer in a thyroid nodule through biopsy. Doctors may recommend removing the nodule when there is doubt.
Do they go away on their own?
According to an ATA study, thyroid nodules that occur due to iodine deficiency may resolve on their own over time if people increase their iodine intake. In 618 participants with thyroid nodules, roughly one-third of single nodules were no longer present at the 11-year follow-up.
The researchers concluded that increasing iodine intake through iodized salt might be the reason for the disappearance of the nodules.
In other cases, benign thyroid nodules may grow larger over time, and people may need treatment to remove them.
Diagnosis
In most cases, people may not have any symptoms of a thyroid nodule. A doctor may find a thyroid nodule through a routine physical examination or an imaging test of the neck to check for another condition. Doctors may recommend tests on people with symptoms or risk factors.
Tests to investigate unusual thyroid activity include:
- ultrasound to see if a nodule is present, how big it is, and if it contains fluid
- a blood test to assess thyroid hormone levels
- a biopsy to remove and test a small piece of tissue
- a nuclear thyroid scan, which uses radioactive medication to provide imaging of the thyroid gland
A fine needle biopsy or aspiration can show whether a nodule is cancerous or not. The doctor will insert a thin needle into the thyroid gland and suction out a few cells for testing.
The doctor may recommend surgery to remove the nodule and examine the tissue more closely.
A nuclear thyroid scan can show whether the thyroid gland is working correctly. For this test, the individual takes radioactive iodine by mouth or intravenously. They then have a scan to see how well the thyroid gland is working and whether any nodules are present.
Outlook
Over 90% of thyroid nodules are benign. Even if thyroid cancer is present, most cases are curable, and they rarely become life-threatening. However, some forms of thyroid cancer can be more aggressive than others.
According to the NCI, the 5-year relative survival rate for people with thyroid cancer between 2011–2017 was 98.3%Trusted Source.
If a nodule is not cancerous, it may still need treatment, monitoring, or both. If people require surgery to remove the thyroid gland, they may need to take medication to supply the body with enough thyroid hormones.
Summary
A thyroid nodule is an abnormal lump in the thyroid gland due to a build-up of thyroid cells.
Most thyroid nodules will not cause any symptoms, and people may discover a nodule through a routine check-up.
In some cases, people may feel a lump toward the front of the throat and have other symptoms, such as fatigue or mood changes.
Most thyroid nodules are harmless and non-cancerous. People will need treatment for a nodule if it is causing difficulty breathing, swallowing, or causing excess thyroid hormones.
In some cases, a thyroid nodule may be cancerous, and people will need surgery to remove any harmful thyroid cells.
A person should always contact their doctor if they think they may have a thyroid nodule.
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