What are thyroid nodules?
Thyroid nodules are abnormal lumps on the thyroid gland, located in the front of your neck. In many cases, you can’t feel them and won’t have any other symptoms. Thyroid nodules are often discovered when your doctor orders imaging tests for another reason.
It’s not unusual to develop thyroid nodules. Up to two-thirds of adults in the U.S. have them, according to a study in JAMA Internal Medicine. Thyroid nodules can affect anyone, but they’re more common in women, older people, and smokers.
An ultrasound can help determine if a nodule is worrisome. Worrisome nodules appear dark and solid on the ultrasound scan. They tend to have irregular borders and contain calcifications. A larger sized nodule, measured by greatest diameter, can also be concerning. —Dr. Rachel Arakawa
Nodules range in size from 1 cm to 4 cm or larger. You may also develop a goiter, which is an enlargement of the thyroid.
Most nodules aren’t cancerous. But according to a study in the New England Journal of Medicine, thyroid cancer occurs in 5% to 15% of nodules, so it’s important that any lumps in your neck are examined by your doctor.
To check for cancer, your doctor will order ultrasound scanning. Depending on the size of the nodules, you may need a needle biopsy, which is when a needle is used to remove tissue from the nodule for testing.
Benign vs. malignant thyroid nodules
There are some signs that doctors look for to help figure out whether a thyroid nodule is benign (non-cancerous) or malignant (cancerous). Benign nodules feel soft to the touch, like a rubber ball, and move easily when being pushed.
Some benign thyroid nodules can start producing large amounts of thyroid hormone, which are called “hot” nodules. They can cause symptoms like:
Malignant nodules tend to feel firm and fixed in place. The surrounding lymph nodes may also become enlarged, so you may notice additional lumps in your neck.
How fast a nodule grows is hard to predict. Some grow over time and others don’t grow at all. The best course of action is to follow them on ultrasound on a regular basis. —Dr. Arakawa
Another sign that a nodule is cancerous is if it grows rapidly. You may develop other symptoms as the nodule grows, including:
- Difficulty swallowing
- Neck discomfort
- A sensation that something is stuck in your throat
- Hoarseness (due to damage to the nerve attached to the voice box)
How are thyroid nodules diagnosed?
If your doctor thinks you have thyroid nodules, you will have an ultrasound, which is the most accurate way of identifying the size, number, and other physical features of the nodules.
Based on what the ultrasound shows, your doctor will make a decision about whether the nodules should be biopsied (a sample tissue removed) to look for cancer cells. Nodules with irregular borders, calcifications, and lower density, and those that are taller than they are wide suggest cancer, so they should be biopsied.
A thyroid biopsy is called fine-needle aspiration (FNA). Your doctor will prick the area 3 to 4 times with a small needle to collect thyroid cells. They will be studied under a microscope. Benign nodules can be monitored with repeat ultrasounds at regular intervals, but malignant nodules must be surgically removed.
What is a normal size for thyroid nodules?
Thyroid nodules range in size—your doctor will decide what to do depending on their size.
- Tiny nodules, which are less than 1 cm in diameter. These aren’t usually biopsied.
- Nodules larger than 1 cm with suspicious features are biopsied. Those that are slightly larger and have fewer suspicious features may not be biopsied until they reach a size of 1.5 to 2 cm.
- Very large nodules (greater than 4 cm) are surgically removed. This is necessary because of an increased risk for thyroid cancer and potential to damage nearby structures in the neck.
Nodules of any size that get bigger should also be biopsied.
A common misconception is that nodules can be shrunken by medications, such as thyroid hormone replacement. This was an approach used by doctors a long time ago, but it was found to be ineffective. In fact, it can cause harm to the heart in the form of irregular and fast heartbeats and weaken bones so it is no longer a recommended treatment. —Dr. Arakawa
How to check your thyroid
During your annual exams, your doctor will examine your thyroid to see if it appears enlarged. Your doctor will check the size, texture, and presence of nodules with their fingers. They will ask you to swallow, which raises the thyroid gland higher in the neck and allows them to feel it more easily. They will also feel for enlarged lymph nodes in your neck.
It is not recommended that people do thyroid self-exams at home. Self-exams have not been shown to improve outcomes of thyroid cancer and they may lead to unnecessary worry, diagnostic tests, and invasive procedures.
When to see a doctor
All thyroid nodules should be examined by your doctor. If you have any of these symptoms—rapid enlargement of your neck, difficulty swallowing, hoarseness—make an appointment with your doctor right away.
Dr. Rachel Arakawa is an Assistant Professor in the Division of Endocrinology, Diabetes, and Bone disease. She completed her residency training in Internal Medicine and fellowship training in Endocrinology at the Columbia University Medical Center of New York Presbyterian Hospital. Her clinical interests include thyroid, adrenal, pituitary, parathyroid, and metabolic bone disease. She has conducted research in obesity and the effects of bariatric surgery on hormones of glucose and energy homeostasis. She has expertise in a wide variety of endocrine disorders and is committed to providing exceptional care to patients.