A nodule often feels like a bump on the side of or in the middle of the throat. If the nodule is large, or if the patient is very slender, a nodule may be visible as a lump in the front of the neck. More often, however, it cannot be detected by sight or touch.
The American Thyroid Association estimates that by age 60, 50 percent of people have a thyroid nodule. Research has suggested that 30 percent of people aged between 19 and 50 have nodules that can be detected by a scan.
Some nodules can be felt at the front of the throat.
Some nodules can be felt easily, while others are hidden deep in the thyroid tissue or located very low in the gland. This makes them difficult to feel.
Thyroid nodules may be single or multiple, and there are different types.
A multinodular goiter is a thyroid gland that contains multiple nodules.
A thyroid cyst is when the nodule is filled with fluid or blood.
"Hot" nodules are those that secrete thyroid hormone, but "cold" nodules do not secrete any hormone.
If the nodule produces thyroid hormones in an uncontrolled way, without regard to the body's needs, it is referred to as autonomous.
Often, thyroid nodules have no signs or symptoms, but if symptoms do appear, they may be related to the location of the nodules. The thyroid gland sits in front of the throat, adjacent to the trachea, or windpipe, and the esophagus.
Large nodules may encroach on or even compress these parts, leading to hoarseness in the voice, breathing difficulties, problems with swallowing, or even choking when lying flat.
The lymph nodes in the neck may increase in size, known as local lymphadenopathy.
A small number of patients complain of pain at the site of the nodule that can travel to the ear or jaw.
Thyroid nodules can be triggered by a number of factors, but often, the cause is unclear.
One known cause for thyroid enlargement is iodine deficiency. Iodine is an essential part of the diet, because the body needs it to produce thyroid hormone. According to the American Thyroid Association, iodine is available in the diet through eggs and dairy products, seafood and meat, and some breads.
Without iodine, the body cannot make enough hormone, and this can lead to an enlargement of the thyroid, known as a "goiter." However, low iodine may correlate with other thyroid problems, such as thyroid nodules.
A thyroid nodule can also stem from an inflammation of the thyroid gland. This is known as subacute thyroiditis. Though rare, it can happen after a viral infection, for example, an upper respiratory virus, the flu, or mumps. The inflammation usually involves a very tender or painful thyroid, and the thyroid may feel bumpy.
Hashimoto's thyroiditis is an autoimmune condition where the body's immune system attacks the thyroid gland.
The exact trigger is unknown, but a number of factors may be linked to it. These include having a family member with thyroid disease, being exposed to radiation, and someone who has had excessive iodine exposure.
Women are seven times more likely to be affected than men.
People may also have a multinodular goiter or a colloid adenoma, a benign overgrowth of the gland that can cause palpable nodules. Most are harmless but their visibility can be frustrating.
Still other thyroid nodules are cysts, which can be filled with fluid, colloid, or blood.
Some thyroid nodules produce extra thyroxine, a hormone that is secreted by the thyroid gland. Symptoms can include unexplained weight loss, nervousness and tremor, fast or irregular heartbeat and intolerance to heat.
Thyroid nodules are often discovered incidentally, or unintentionally, during an imaging test for another condition.
A blood test can reveal any abnormally low or high levels of thyroid hormone and thyroid-stimulating hormone in the body.
The tests will show whether the problem is inside the thyroid gland itself, or if it is elsewhere.
If the physician suspects an autoimmune disease, there may be tests for serum thyroid autoantibodies. These tests measure whether antibodies are present that may be directed towards the thyroid gland, and if so, how much.
A fine needle biopsy/aspiration of the nodule can show whether it is or is not malignant.
In a fine-needle biopsy, a thin needle is inserted into the thyroid gland and a few cells are suctioned out. These can be examined to see if they are cancerous.
If the biopsy suggests cancer, or if the nodule is increasing in size rapidly, surgery may be necessary to remove the nodule entirely. Surgery will also enable the physician to examine the nodule more closely.
Radionuclide scanning with radioactive chemicals can also be used to evaluate a thyroid nodule.
In radionuclide scanning, a patient with a suspected thyroid nodule takes radioactive iodine by mouth or intravenously.
Any part of the body that absorbs this iodine will "light up."
Iodine accumulates in the thyroid gland, so the thyroid would be expected to light up.
The speed and location at which the iodine collects can reveal how the thyroid gland is functioning, and if there are any nodules.
Treatment for thyroid nodules depends on the cause.
If cancer is suspected, surgery will be carried out to remove the cancerous tissue.
Surgery may also be recommended if:
- If the nodule is larger than 4 cm across
- A complex cyst is seen during an ultrasound scan
- There are signs of compression.
If the nodule is benign, the physician will continue to monitor the patient closely with physical exams and an ultrasound every few months.
If the nodule is "hot," or producing hormones, non-surgical treatment options include using radioactive iodine to destroy the gland, and taking medication to block the effects of the thyroid hormone.
The American Thyroid Association states that over 90 percent of thyroid nodules are benign, or not cancerous.
If a nodule is malignant, it can normally be treated, but treatment depends on the type of disorder.
Most cases are well-differentiated cancer, and the prognosis is excellent, especially if it is diagnosed in the early stages. Poorly differentiated cancer types are harder to treat.
In 2013, 637,115 people were living with thyroid cancer in the United States, and in 2006 to 2012, 98.1 percent of people who were diagnosed with thyroid cancer survived for at least 5 years.