When To Worry About Thyroid Nodules?

Introduction

According to the British and American Thyroid Associations, an average of 4 out of every 10 individuals will develop thyroid nodules at some point in their lives.^1,2 A pondering question then is if thyroid nodules are a cause for worry. In this article, we will discuss what thyroid nodules are and when there is cause for concern. 

The thyroid glands

The thyroid gland is a gland found in the anterior (front) neck and it secretes thyroid hormones and calcitonin. The thyroid gland comprises two pear-shaped lobes that lie laterally on opposite sides of the windpipe (larynx). These lobes are connected by thyroid tissue called the isthmus. Because of the hormones the thyroid gland produces, it controls many body functions which include metabolic rate, blood calcium levels, blood glucose balance, heart rate, digestion, central nervous system function, and more.^1,2

What is a thyroid nodule?

A normal thyroid gland in its usual size can rarely be felt when touching the throat. A thyroid nodule is however a lump that grows within the tissue of the thyroid glands and may be felt by the affected person when swallowing or upon touching. Thyroid nodules can grow in only one or both lobes. The nodules may be solid or sometimes contain liquid and may grow quickly or very slowly. A nodule that contains liquid is commonly referred to as a cystic nodule.²

I have noticed a lump in the front of my neck, should I be worried?

Thyroid nodules are very common, with 40% of the global population experiencing thyroid nodules at some point in their lives. A vast majority of thyroid nodules are benign, meaning that they are not cancerous or malignant. For instance, though every 4 in 10 people can be expected to develop thyroid nodules, in the UK the annual cases of thyroid cancer reported is less than 5 in 100,000 people. Though thyroid cancer is the most significant cause for alarm, the non-cancerous thyroid nodules can also, however, be a cause for concern.¹ 

What may have led to my thyroid nodules?

Thyroid nodules may result from different factors. These factors include:

Iodine deficiency

Iodine is the major raw material used by the thyroid gland to produce its hormones. When there is a lack of iodine within the human body, hypothyroidism (reduced levels of thyroid hormones) occurs. The body in response to the reduced levels of thyroid hormones, pushes the thyroid gland to work harder than it normally does to draw in as much iodine as possible to produce more hormones. The extra work the thyroid does causes it to develop nodules. Iodine deficiency is, however only common in certain locations in the world where local diets lack iodine-containing foods. Iodine-containing foods include fresh leafy vegetables and greens, fruits, and iodine-fortified salt.²

Infections

Sometimes, upper respiratory infections affect the thyroid glands, causing inflammation in the thyroid. The inflammatory process causes damage to thyroid cells and can also trigger the development of nodules within the thyroid gland if it is prolonged. Subacute thyroiditis or De Quervian thyroiditis is the inflammation of the thyroid caused by a viral upper respiratory tract infection.³

Autoimmune conditions

People with a family history or personal history of autoimmune conditions such as vitiligo and Addison’s disease also have higher odds of developing thyroid nodules through an auto-immune mediated inflammatory attack on the thyroid gland. A form of this is Hashimoto thyroiditis which occurs as a result of auto-antibodies to a normal protein produced by the thyroid called thyroglobulin. Another form of autoimmune thyroiditis is called postpartum thyroiditis and occurs within a few months after delivering the baby.²

Cancer

Thyroid cancer only accounts for a very small fraction (less than 5%) of thyroid nodules (3). The commonest thyroid cancer type (papillary adenocarcinoma) has an association with radiation exposure earlier in life and also runs in some families.² Thyroid inflammation is a response to drugs and radiation to the neck.

Signs of problematic thyroid nodules

Though only a small fraction of thyroid nodules are cancerous, even the benign forms can be problematic. We will take a look at some of the general signs and symptoms of thyroid nodules.²

Very large nodules

Most thyroid nodules are smaller than 1cm and grow slowly. A thyroid nodule that grows quickly and exceeds 1cm in size then it could indicate thyroid cancer.

Hyperthyroidism or thyrotoxicosis

This occurs when the thyroid produces and releases excessive amounts of thyroid hormones into the bloodstream, and is seen in some scenarios of thyroid nodules. Symptoms include palpitations, feeling hot and sweating even in cold weather, hot flashes, diarrhoea, weight loss, insomnia, irritability, poor concentration, menstrual irregularities, and bulging eyes in some individuals.

Hypothyroidism

In contrast to hyperthyroidism, this occurs when the thyroid gland does not produce and release enough amounts of thyroid hormones into the bloodstream and is seen in some cases of thyroid nodules. Reduced levels of thyroid hormones result in reduced metabolism, tiredness, lethargy, intolerance to cold, dry skin, hair loss, slowing of intellectual and motor activity, constipation, weight gain, menstrual irregularities, and puffy hands and feet in some individuals.

Pressure

Occurs because of the increased mass of the thyroid gland compressing on nearby structures in the neck. Symptoms include difficulty swallowing, difficulty breathing, a change in voice quality, and snoring when lying to sleep.

Other swellings in the neck

Other swellings in the neck away from the may indicate thyroid cancer that is infiltrating cervical lymph nodes.

Thyroid pain

Sometimes, thyroid nodules present with pain, especially in those from inflammatory causes and cancer.

Family history of cancer

A family history of cancers, especially thyroid cancers or other thyroid cancer-associated tumours, increases the odds of the thyroid nodule being cancerous.

As such, even if none of the other symptoms discussed is present, the thyroid nodule should still be taken seriously and medical attention sought for investigations. 

Investigations for thyroid nodules

Tests that may be performed on a person who has developed thyroid nodules include:^1,2

• Fine needle aspiration cytology (FNAC) for a cytopathology study to determine if the nodule is cancerous or malignant
• Ultrasound scan to determine the size of the thyroid and nodules
• CT scan to assess compression of the windpipe by the thyroid
• Thyroid function tests and Radioactive iodine uptake tests to conclusively ascertain if the nodules are hyperthyroid or hypothyroid 

Management of thyroid nodules

The management of thyroid nodules varies based on whether it is malignant or benign in nature, whether it has hyperthyroid or hypothyroid symptoms, and whether the cause is long-standing or self-limiting.

Non problematic or asymptomatic

If the nodule is small, growing very slowly, isn’t causing any pressure symptoms like difficulty swallowing, isn’t causing pain, isn’t causing symptoms of hyperthyroidism or hypothyroidism, and has been determined as non-malignant, then it may be left alone.²

Idoine deficiency

In cases where the thyroid nodule is due to iodine deficiency, an increase in iodine uptake will resolve the condition.²

Thyroiditis 

Postpartum thyroiditis and subacute thyroiditis are self-limiting and resolve over time. Such patients may or may not be given medical therapy, depending on the severity of symptoms. 

Hyperthyroidism and hypothyroidism 

Long-standing hypothyroidism will, however usually be managed with levothyroxine as replacement therapy, while long-standing hyperthyroidism may be managed using either antithyroid drugs, radioactive iodine, or surgery.² 

Patients with hyperthyroidism can aim to consume more calories per day to make up for the increased metabolism and prevent excessive weight loss. On the other hand, patients with hypothyroidism should look to consume more veggies and less calorie-dense food to combat excessive weight gain.^4,5

Apart from surgery being an option for treating hyperthyroid patients, surgery is also indicated in cases where the nodules are causing life-threatening compression of the larynx or windpipe.²

Thyroid cancer 

Thyroid cancers are managed using one or a mixture of surgery, chemotherapy, radioactive iodine therapy, and radiotherapy, depending on the type of cancer. The prognosis of thyroid cancers is good, especially in younger patients and in those assigned female at birth (AFAB). The prognosis of thyroid cancer, however, worsens with increasing age, especially in those assigned male at birth (AMAB), with increasing size or grade of the tumour or nodules, and with increasing involvement of distal lymph nodes and metastasis.² 

Summary 

Thyroid nodules are typically benign. However, if you feel a lump in the anterior part of your neck together with any of the worrying features described, such as a painful nodule, weight loss, hoarseness of voice, and difficulty breathing, you should visit a hospital for thorough examination and investigations. This will help in the early detection and treatment of the condition, should it be serious or cancerous.