Thyroid nodules: Causes, diagnosis, and treatment options

You might notice a growth or feel a small irregularity on the lower front of your neck. Or your doctor might feel a change during a routine exam of your thyroid gland, or a check for lymph node swelling in the same area.

If you’ve never been diagnosed with a thyroid problem, chances are you’re not even aware of the small, butterfly-shaped gland that wraps around the front of your trachea. But your thyroid influences the rate at which cells, tissues, and organs in your body function, from your muscles, bones, and skin to your digestive tract, brain, and heart. So if your doctor feels something unusual or you have symptoms that could be related to a thyroid problem, your doctor will likely order a blood test and perhaps an imaging test like an ultrasound.

What is a thyroid nodule?

A thyroid nodule is made up of clumps of thyroid cells. Nodules can develop on the outer surface of the gland, where your doctor might feel them during an exam. But they can also be very small or develop inside the gland, where they may not be detectable by touch.

Thyroid nodules are very common. Most of them are benign (noncancerous) and don’t affect thyroid function. However, thyroid nodules can cause a hormone imbalance called hyperthyroidism, where your thyroid produces too much of a hormone called thyroid-stimulating hormone (TSH).

A more common cause of hyperthyroidism is Graves’ disease, an autoimmune disorder. In people with Graves’ disease, the thyroid gland usually becomes diffusely enlarged rather than forming one or more discrete nodules.

If you’re experiencing hyperthyroidism, you might have a racing pulse; feel anxious, nervous, or irritable; or have trouble sleeping. You might also have unexpected weight loss, heat intolerance, or feel especially fatigued.

A person with one or more thyroid nodules might also have an underactive thyroid, known as hypothyroidism. Symptoms of hypothyroidism include fatigue, depression, weight gain, constipation, and dry skin. Those symptoms may be different in older people. The condition often is secondary to the autoimmune condition called Hashimoto’s disease, which is much more common in women than in men.

Why do thyroid nodules form?

Thyroid nodules can form in response to several factors and conditions. Sometimes they’re caused by a simple overgrowth of thyroid tissue, known as thyroid adenoma. The original cause of adenomas is unknown, but these types of thyroid nodules don’t tend to be cancerous. Adenomas can sometimes evolve into fluid-filled cavities called cysts.

Chronic inflammation of the thyroid (such as what can happen in Hashimoto’s disease) can also result in thyroid nodules, as can iodine deficiency (though uncommon in the United States). Finally, thyroid nodules can be caused by cancer.

What happens if a nodule is suspicious?

If your doctor finds a thyroid nodule (or if you exhibit symptoms consistent with thyroid changes), they may recommend several diagnostic tests such as blood tests, ultrasound, or a thyroid nodule biopsy. While most thyroid nodules are benign, certain features and risk factors may increase the suspicion of cancer, including:

• rapid growth of nodules over a series of weeks or months
• a nodule that feels hard to the touch
• irregular shape or texture
• associated symptoms including unexplained weight loss, changes in voice (hoarseness), difficulty swallowing or breathing
• a family history of thyroid cancer or genetic conditions like multiple endocrine neoplasia (MEN)
• a history of radiation exposure, particularly in childhood
• age and gender: benign thyroid nodules are common in women, but more likely to be malignant if found in men, or in people under the age of 20 or over the age of 70.

Treating and managing noncancerous thyroid nodules

If left untreated, thyroid nodules can lead to problems swallowing or breathing, or to hyperthyroidism. So it’s likely that your doctor will want to create a treatment plan to monitor and manage the condition.

If a thyroid nodule is deemed benign, your doctor may recommend several thyroid nodule treatments, including:

• Observing and monitoring: Many benign nodules remain stable or grow slowly. Your doctor may recommend periodic ultrasound examinations, possibly coupled with blood tests to check thyroid hormone levels.
• Thyroid hormone suppression therapy: In some cases, a doctor may recommend a synthetic thyroid hormone to suppress the stimulation of the pituitary gland — but this approach is less common due to questions around its efficacy and potential side effects.
• Radioactive iodine therapy: More commonly used for nodules that are overactive (toxic nodules) rather than benign nontoxic nodules, this treatment is aimed at shrinking the affected nodule.
• Surgery: If the nodule is large or interfering with swallowing or breathing, your doctor may recommend surgery.
• Ethanol ablation: Usually reserved for cystic nodules, this is a minimally invasive procedure where the cyst is drained and then ethanol is injected into the nodule.
• Laser or radiofrequency ablation: These techniques use heat to destroy or shrink the nodule.

The connection between thyroid cancer and GLP-1 agonists

GLP-1 agonists like Ozempic and Wegovy are weight-loss drugs prescribed for the treatment of type 2 diabetes and, more recently, obesity. However, some animal studies and other recent research have demonstrated a possible connection between GLP-1 agonists and an increased risk for thyroid cancer, particularly medullary thyroid carcinoma (MTC). Here’s an overview of the most recent research.

• Animal studies: Studies in rats have shown an association between GLP-1 agonists and increased risk of thyroid growths in thyroid C-cells in rodents.
• Human studies: While researchers were concerned to find GLP-1 receptors on thyroid C-cells in rodents (thyroid C-cells produce a hormone that helps regulate calcium levels in blood), in human studies, the evidence linking GLP-1 agonists to increased thyroid cancer risk, including MTC, is lacking.
• Bottom line: Research suggests that the risks of GLP-1 agonists and thyroid cancer in humans are far lower than those in rodents. However, regulatory agencies like the FDA have issued a warning about the potential risk of MTC following the use of GLP-1 agonists. As such, they advise against the use of GLP-1 agonists in patients with a personal or family history of MTC or multiple endocrine neoplasia syndrome type 2 (MEN 2).

It's important to remember that thyroid nodules are very common, and that the majority are not cancerous. But it’s always a good idea to arrange a medical evaluation if you notice any lumps in your neck, or you observe any associated symptoms of thyroid imbalance.