Dr Dennis Chua, ear, nose and throat specialist at Mount Elizabeth Hospital, talks about the thyroid and the common conditions associated with it.
What is the thyroid gland?
The thyroid gland is a butterfly shaped gland in the neck which secretes a hormone that helps the body use energy and keeps the brain, heart, muscles and other organs working as they should.
Thyroid nodules (lumps) can develop in thyroid glands and are common. It is estimated that 1 in 20 patients will have a thyroid nodule that can be felt. Thyroid nodules are more common in women than in men. However, if a male has a thyroid nodule, the chance of him developing thyroid cancer is higher.
What causes thyroid lumps?
Patients frequently ask if a thyroid nodule or malignancy is caused by smoking, diet or lifestyle. The simple answer would be no. Most thyroid nodules grow spontaneously. Genetics can possibly be a factor, since thyroid nodules have been noted to run in families. Radiation exposure especially during childhood may also increase the risk of thyroid nodules and cancer, though this is an uncommon cause.
Besides the presence of a neck lump that tends to move with swallowing, there are frequently no other symptoms. Most patients with a thyroid nodule will have a normal thyroid hormone level and thus will not have symptoms of excessive (hyperthyroidism) or inadequate thyroid hormone levels (hypothyroidism).
Patients with advanced thyroid cancer can present compressive symptoms such as breathlessness, inability to eat (as the swallowing tube is compressed), hoarseness and pain.
Investigating thyroid nodules (lumps)
A thyroid nodule is simply a lump that grows on the thyroid gland. It can be solid or filled with liquid (cystic). A thyroid nodule that is bigger than 1 – 1.5cm generally needs a thorough investigation. This may include:
- Ultrasound scan thyroid
- Fine needle aspiration cytology (FNAC)
- Blood tests
- Nuclear scans of the thyroid
- Diagnostic lobectomy / hemithyroidectomy
- Total thyroidectomy
- Radioiodine (RAI)
Surgical approaches for thyroid lumps
Conventional thyroid surgeries are performed with a horizontal skin incision measuring about 6cm in the front of the neck. The gland is then removed, while taking care to preserve the recurrent laryngeal nerves (which controls the voice box) and the parathyroid glands (which control calcium levels).
The scar usually heals very well in 6 months if proper care is taken after surgery. Other approaches include minimally invasive video assisted thyroid surgery (Mivat), robotic thyroid surgery and even transoral surgery. For selected patients, Mivat can be an option where the thyroid gland can be removed leaving just a small scar measuring 2.5cm in the neck.
This is an option for patients with a history of hypertrophic or keloid scars. However, patient safety is of utmost importance and a complete removal of a suspected thyroid cancer with clear margins is the priority in choosing the appropriate surgical approach. There should never be any compromise on complete clearance of thyroid cancers for the sake of cosmetic appearance.
Graves' disease
This is an auto-immune condition where the body produces antibodies that stimulate the thyroid gland to enlarge and produce excessively high thyroid hormone levels, resulting in hyperthyroidism. Symptoms include rapid, irregular heartbeat (palpitations), unexplained weight loss, muscle weakness, hand tremors, difficulty sleeping, nervousness or irritability, and diarrhoea.
Patients with Graves' disease may also have bulging eyes, double vision and eye dryness possibly requiring an evaluation by an eye specialist.
Treating Graves' disease
Medication: Antithyroid medication can be used to decrease the amount of thyroid hormone production. However, the treatment can take up to 18 months and there is a high relapse rate of more than 50%. During the treatment period, it can be challenging to titrate the medication to obtain a normal thyroid hormone level.
Radioiodine (RAI): The aim of the treatment is to achieve hypothyroidism in 3 months. Subsequently, thyroid hormone replacement will have to be initiated. If thyroid function does not normalise within 6 – 12 months of treatment, a second course at a similar or higher dose can be given. There is a small possibility that RAI can trigger a 'thyroid storm'. This can be potentially fatal with the patient suffering from heart attacks or heart failure. RAI is also not an option for patients who are pregnant or intending to get pregnant within the next 6 months.
Surgery: A total thyroidectomy or subtotal thyroidectomy (leaving a small thyroid remnant behind so the dose of thyroid hormone replacement can be lower) can be performed. This provides a quick solution to a disease that can otherwise require months of medical treatment and is suitable for patients who understand the benefits versus the risks of the surgery.
Hashimoto's thyroiditis
This is an auto-immune condition whereby the body's antibodies attacks the thyroid gland resulting in hypothyroidism.
Symptoms include fatigue, weakness, weight gain, coarse hair, dry skin, hair loss, cold intolerance, frequent muscle aches, constipation, depression, memory loss, abnormal menstrual cycles, and decreased libido.
Diagnosis is achieved with blood tests including antithyroid antibodies. Long-term monitoring is necessary.
The thyroid gland is an important organ in our body that performs essential functions. Thyroid conditions can include thyroid cancers or thyroid hormone level dysfunction. Thyroid cancers usually have good survival rates when detected early and patients can be cured. Thyroid hormone level dysfunction requires careful management to prevent the harmful side-effects of hyperthyroidism or hypothyroidism.
