Overview

What are thyroid?

The thyroid is a butterfly-shaped gland located just below your Adam’s apple, with its wings on either side of your windpipe. It produces thyroid hormone, which controls your metabolic rate.

Causes

The exact cause of thyroid nodules is not known, but the following factors may be involved:

• A lack of iodine in your diet
• A thyroid condition such as goitre or hypothyroidism, in particular Hashimoto’s thyroiditis
• Exposure to radiation treatments
• A history of thyroid nodules in your family

Is your neck lump a thyroid nodule?

If you have a lump in the middle of your neck (below your Adam’s apple) or just off the center, which moves with swallowing, it is probably a thyroid nodule. Your doctor will be able to confirm this finding. The lump you feel may be either a solitary nodule or a dominant nodule in a background of multiple nodules, or even a diffusely enlarged thyroid gland.

Symptoms

Thyroid nodules usually do not cause symptoms, but some symptoms include :

• Pain – if there is bleeding into the nodule or inflammation.
• Difficulty swallowing or breathing – if the thyroid gland or nodule is large.
• Hyperthyroidism symptoms like heat intolerance, fast heart rate, weight loss and tremors – if the nodule produces excessive thyroid hormone.
• Hypothyroidism symptoms including cold intolerance, lethargy, weight gain and weakness – if less thyroid hormone is produced.
• Hoarseness – if there is a cancer invading the nerve supplying your vocal cords. This symptom warrants immediate attention.

Prevention

In Singapore where iodine deficiency is not a problem, there are no preventable causes of thyroid nodules or goitre. Radiation is a risk factor for thyroid cancer, but this is a rare occupational or treatment risk for a small group of individuals.

Diagnosis

Fine needle aspiration cytology (FNAC)

A minor procedure performed in the clinic, a fine needle is inserted into the nodule and cells are withdrawn for evaluation. You will be able to return home or to work immediately. The test aims to determine if your thyroid nodule is cancerous, but the result is occasionally inconclusive.

Ultrasound

Sound waves are used to form a picture of the thyroid gland. It allows your doctor to determine if your thyroid nodule is solid, cystic (fluidfilled) or mixed, the number of nodules and also to take measurements to track the growth of the nodules.

Most importantly, it allows the doctor to identify features that may be suggestive of cancer, including microcalcifications, internal vascularity and hazy boundaries, possibly from invasion of surrounding tissue. It may also be used to help locate nodules and to guide the needle in FNAC for more representative results.

Thyroid scan

You take a small amount of radioactive iodine orally. It is taken up by functioning thyroid cells, which will show up on a scan.

Functioning nodules are less likely to be cancerous. Cold nodules or nonfunctioning nodules require further evaluation with FNAC.

Thyroid function test

A blood test to determine the level of thyroid hormone and thyroid stimulating hormone. It may be useful if you have hyper or hypothyroid symptoms or if you require surgery.

Treatment

This depends on the nature of the nodule, whether it is benign or malignant and also if it causes symptoms.

Cancer

Surgery is the treatment of choice. Depending on the size of the tumour, either half or the entire thyroid gland may need to be removed. Additional treatment like radio-iodine treatment or radiotherapy may be necessary.

Benign nodules

Benign nodules may be observed if not causing any symptoms. Follow-up of the nodules is usually by ultrasound. The interval will be decided by your doctor.

Surgery is an option if symptoms are present, including difficulty swallowing or breathing, or even just to remove the unsightly lump.

Indeterminate
 
If the nature of the nodule is indeterminate on FNAC, your doctor will discuss with you the options of close observation versus surgery. The risk of your nodule being cancerous depends on the exact findings on ultrasound and FNAC.

How is thyroid surgery performed?

Thyroid surgery is performed under general anaesthesia. It may be:

• Hemithyroidectomy – removal of half the thyroid gland. For benign nodules or small cancers.
• Subtotal Thyroidectomy – removal of most of the gland, aiming to leave behind suffi cient tissue to meet thyroid hormone requirements. For benign nodules, toxic goitre including Graves disease or nodular goitre.
• Total Thyroidectomy – removal of the entire thyroid gland. For larger cancers, nodular goitre or toxic goitre including Graves disease.

Your surgeon will explain to you which operation you require and the reason for it.

What are the risks of thyroid surgery?

Other than the risks that apply to all surgery including general anaesthesia risk, risk of bleeding and infection, the risks specific to thyroidectomy are:

• Hoarseness – due to injury of one recurrent laryngeal nerve, which supplies the muscles controlling the vocal cord. Injury is rare and usually temporary, but may be permanent.
• Difficulty breathing – due to injury of both recurrent laryngeal nerves. Injury is very rare and usually temporary, but may be permanent. May require a tracheostomy to secure airway.
• Low calcium – due to disturbance of the parathyroid glands that control calcium levels in the body. Usually temporary, rarely permanent.

What is scarless or minimal access thyroid surgery?

In suitable patients, thyroid surgery can be performed without using a neck incision. The surgery may be endoscopic or robot-assisted. Skin incisions are located in the axilla or armpit and are less visible than a neck scar and easily hidden by clothing.