What Is Nodular Hashimoto’s Thyroiditis?

The suffix -itis means "inflammatory disease." So, thyroiditis, in simplified terms, is inflammation of your thyroid. The thyroid is on the front of the neck and shaped like a small bowtie. It produces thyroxine (T4) and triiodothyronine (T3), which regulate your metabolism.

Hashimoto's thyroiditis is an autoimmune disorder. In the US, it’s the most common cause of having an underactive thyroid (hypothyroidism).¹ More rarely, it can cause overactive thyroid (hyperthyroidism).

Nodular Hashimoto's thyroiditis means that a lump (or multiple lumps) in your thyroid is one of your symptoms. 

The primary concern with Hashimoto's thyroiditis is that the immune system attacks healthy thyroid cells. Over time this disrupts many bodily functions, like your heart rate, digestion, and sleep. 

However, the disease is generally considered manageable. Furthermore, its prognosis is excellent for those who receive synthetic thyroid hormone replacement medication.

Some individuals with Hashimoto's thyroiditis will develop thyroid nodules. However, they may not know until a doctor discovers them during a routine checkup.

Thyroid nodules are usually benign (non-cancerous). They may be small and lack any noticeable symptoms. However, nodules can grow and interfere with breathing and swallowing, which may require surgery.

What exactly is a thyroid nodule?

A thyroid nodule is a fluid-filled or solid lump in your thyroid gland. Your thyroid can develop a single nodule or a cluster of nodules (multinodular). 

Thyroid nodules are sometimes classified as cold or hot. 

Cold thyroid nodules do not produce any thyroid hormone.

Hot thyroid nodules produce excessive thyroid hormones and can cause hyperthyroidism (accelerated metabolism).

A thyroid scan will determine whether nodules are hot or cold but won’t diagnose whether the nodule is cancerous or not. Instead, your doctor may order an ultrasound or fine-needle biopsy to make that determination.

What are the symptoms of thyroid nodules?

Most thyroid nodules are symptomless and aren’t cause for concern. Most times, you will neither see nor feel them. However, if a nodule is visibly enlarged or noticeable to the touch, you may experience:

• An enlarged thyroid gland (goiter) 

• Difficulty breathing or swallowing

• Pain or pressure in the front of your neck

• A hoarse voice or vocal changes

Additionally, you may develop hyperthyroidism (overactive thyroid).  Symptoms of hyperthyroidism include:

• Difficulty sleeping

• Unexplained weight loss despite an increased appetite

• Nervousness or anxiety

• Increased and irregular heartbeat

• Muscle weakness

• Shakiness

• Restlessness

• Increased sweating

• Frequent bowel movements

• Intolerance to heat

Alternatively, you may develop hypothyroidism (underactive thyroid). Common symptoms include:

• Unexplained weight gain

• Chronic fatigue

• Sensitivity to cold

• Hair loss or having thin or brittle hair

• Depression

• Pallor (paleness)

• Constipation

• Dry skin

• Muscle pain

• Enlarged tongue

• Memory loss

What causes thyroid nodules?

Thyroid nodules occur due to an abnormal cluster of growth.  Most thyroid nodules do not have  a clear cause, but research attributes them to:

• Dietary iodine deficiency²

• Cysts in the thyroid³

• Ongoing chronic inflammation of the thyroid

• Cancer (rare)⁴

Hashimoto's thyroiditis

According to research, Hashimoto's thyroiditis affects 2–15% of the global population.⁵ ⁶ Hashimoto's thyroiditis is also known as Hashimoto's disease, chronic autoimmune thyroiditis, or chronic lymphocytic thyroiditis. The immune system attacks healthy cells in the thyroid gland, slowing thyroid hormone production.

Hashimoto's disease can reduce thyroid hormone, prompting an increase in thyroid-stimulating hormone (TSH) to compensate. Increased TSH can make the thyroid grow larger (commonly known as a goiter). Thyroid nodules may form. 

Thyroid cancer

Thyroid cancer may cause a lump in the neck along with pain or swelling that can go up to the ears. There may be a persistent cough or trouble with breathing and swallowing. Thyroid cancer is generally considered highly treatable. According to the American Society of Clinical Oncology (ASCO), the 5-year survival rate for people in the US with thyroid cancer is 98%. However, that estimate is based on many factors. The actual number of people who will live at least five years after thyroid cancer is detected will vary depending on the exact type of cancer and how far it has progressed at the time of diagnosis.⁶

Iodine deficiency

Iodine is essential for the production of the thyroid hormone. When your body lacks iodine, you can develop goiter or hypothyroidism, causing thyroid nodules to form.⁷ Proper dietary iodine is a delicate balance. Too much iodine in your diet can also trigger hyperthyroidism (overactive thyroid).⁷ If possible, speak to a healthcare professional or dietitian for guidelines.

Thyroid adenoma

An adenoma is a non-cancerous tumor. There are two types of thyroid adenomas: follicular (encapsulated) and papillary (projections of tissue). Thyroid cancers may mimic thyroid adenomas, hence the need to differentiate with a biopsy. 

What are the risk factors for thyroid nodules?

Thyroid nodules are quite common, and an estimated 95% are harmless.³ If you notice a lump or mass in the neck, ask your doctor about having an ultrasound to characterize it. Several factors can increase your chances of developing a thyroid nodule. They include:

Age

Your risk of developing thyroid nodules increases as you age. 

Exposure to radiation

If you have a history of exposure to radiation from medical treatments either on the neck or head or environmental exposure, you may be at risk for developing thyroid nodules, thyroid cancer, or thyroiditis.⁸

Sex

Females are more likely to develop thyroid nodules than males. The reason for the increased likelihood is unclear, but researchers suggest that reproductive hormones play a role.⁹

Environment

If you live in a region where iodine is not included in your diet, you are more at risk of developing thyroid nodules. This is because iodine is essential for the production of thyroid hormones. Today, a lack of dietary iodine is not usually a problem in the US. However, it was a major issue a century ago, which is why table salt is usually fortified with iodine in North America.²

What are the complications of thyroid nodules?

Thyroid nodules may cause complications, including:

• Swallowing and breathing difficulty

When a thyroid nodule grows, it may cause difficulty breathing and swallowing.

• Hyperthyroidism

When a hot thyroid nodule produces thyroid hormone, it can lead to excessive production of thyroid in your body and hyperthyroidism. Hyperthyroidism can cause you to have weak muscles, lose weight, become anxious and irritable, and reduce your tolerance to heat.

How is a thyroid nodule diagnosed?

Suppose your healthcare provider notices a nodule during a physical exam. They will most likely refer you to an endocrinologist to rule out cancer and verify that your thyroid still functions properly.

An endocrinologist may perform the following tests:

A physical exam

During a physical examination, the doctor will ask you to swallow. If you have a nodule in your thyroid gland, it will move up and down. Your doctor will also look for signs of hypothyroidism, such as pale, dry skin, or an enlarged tongue. They will check for symptoms of hyperthyroidism like rapid or irregular heartbeat, hand tremors, or overly active reflexes.

Thyroid function test

Your endocrinologist will perform a thyroid function test to test the levels of thyroid hormones in your blood. 

Ultrasound

An ultrasound produces high-frequency sound waves to capture the shape and structure of the nodule. The endocrinologist may also use ultrasound to guide a fine-needle aspiration biopsy.

Fine-needle aspiration biopsy

A fine-needle biopsy is an important way of testing whether a nodule is cancerous or not. A doctor will aspirate (use suction) and a very thin needle to remove fluid or thyroid cells for further examination.

Thyroid scan

Your doctor may also require a thyroid scan. During this test, a very small amount of radioactive iodine will be injected into your bloodstream. Then, you will lie down while a special camera displays images of your thyroid on a screen. Hot nodules that make excess thyroid hormone will be identifiable since they take up more iodine than normal thyroid tissues. The scan will also identify any nodules that take up less iodine — also known as cold nodules.

How is a thyroid nodule treated?

Your treatment will depend on your diagnosis as thyroid nodules can represent multiple pathologies.

Treating benign nodules

If the nodule is small and benign (also known as asymptomatic), your endocrinologist might decide not to prescribe any medication. However, they may call for regular biopsies to monitor the nodules and rule out cancer. Synthetic thyroid hormone therapy may also be recommended if you are diagnosed with hypothyroidism (low levels of thyroid hormone).

Treating nodules that cause hyperthyroidism

If nodules are accompanied by high levels of thyroid hormones, your doctor might prescribe anti-thyroid medication (thioamide drugs) to help reduce the symptoms of hyperthyroidism.

Treatment nodules that cause hypothyroidism

If your nodules cause your thyroid gland to produce fewer thyroid hormones than normal, your doctor will recommend hormone replacement therapy. They will prescribe a synthetic hormone replacement pill to stabilize T4 and T3 hormones.

Treatment for cancerous nodules

Surgery

If you have cancerous nodules, your doctor might remove the nodules (completely or partially) through a surgery called thyroidectomy. The extent of the procedure will depend on the amount of thyroid damage. Nerve damage or vocal cord damage is a possible complication. After having a thyroidectomy, it’s necessary to stay on synthetic thyroid hormone replacement for life. 

Radioactive iodine (RAI) treatment

Radioactive iodine is sometimes used after thyroidectomy to eliminate any remaining thyroid tissue and to treat any remaining cancer.

Is there any way to prevent a thyroid nodule?

At this time, thyroid nodules aren’t considered preventable. However, some risk factors may be in your control, such as avoiding unnecessary radiation exposure. For example, it may be helpful to avoid dental X-rays unless strongly advised by your dentist. Most dentists’ offices will have a special thyroid guard you can wear during imaging to help minimize exposure.

What questions will my doctor ask?

Here are some questions to expect when speaking with your endocrinologist or similar healthcare provider about thyroid concerns:

• Do you have a family history of thyroid nodules?

• Have you undergone radiation treatment on your neck or head?

• Have you had any other thyroid problems before?

The lowdown

Most thyroid nodules are harmless, and you won’t experience significant symptoms. In most cases, people don't realize that they have thyroid nodules since they are often tiny. If your doctor does a physical examination and suspects you have thyroid nodules, they might do other tests like ultrasound, thyroid function test, and fine-needle aspiration or biopsy.

After they determine the type and size of the nodules, they will offer the appropriate treatment. For example, cancerous nodules and those that cause hypothyroidism or hyperthyroidism will be treated accordingly.