A shortage of iodine in the diet is the world’s number one cause of an enlarged thyroid (commonly known as a “goitre”).1 An estimated 0.7 billion people worldwide are affected by iodine deficiency.2 Iodine deficiency is uncommon in Singapore ‒ most goitres that do occur are not associated with iodine deficiency.
A goitre may be an overall enlargement of the thyroid gland or it may be the result of irregular cell growth that form one or more lumps in the thyroid gland (nodules). The most common cause of goitre worldwide is iodine deficiency, although it may still develop in individuals who have enough iodine. In these people, the cause is not well understood.
A person with an immensely enlarged thyroid may have problems swallowing or breathing.3,4
The American Association of Clinical Endocrinologists recommends the so-called “neck check” to help people recognise a possibly enlarged thyroid.5
Simple visual classification can be inaccurate — primarily due to the possibility of human error and variations in individual anatomy (for example, a muscular neck can conceal an enlarged thyroid) — and should by no means serve as a substitute for a specific diagnosis by a doctor.
Thyroid nodules are abnormal growths of thyroid tissue that forms a lump in the thyroid gland. Some people develop a single nodule while others may develop many (multinodular goitre).6 Thyroid nodules are relatively common, with as many as half of all people having at least one nodule by the time they reach the age of 60.7
Most thyroid nodules do not cause symptoms.6 They often go undiscovered until the next routine medical examination or imaging tests, such as computed tomography (CT) scans or neck ultrasound, which are usually done for unrelated reasons.6
Uncommonly, thyroid nodules may cause sudden painful swelling in the neck due to bleeding. Occasionally, advanced thyroid cancer may cause symptoms such as difficulty breathing, difficulty swallowing and hoarseness of voice.6 If you have these symptoms, a doctor should be consulted immediately.
About 10% of thyroid nodules may produce extra thyroid hormones resulting in symptoms of hyperthyroidism (a condition known as toxic thyroid nodule). Thyroid nodules may also be found in patients with autoimmune hypothyroidism (known as Hashimoto’s disease). In this case, the patient may experience symptoms of hypothyroidism.8
If you believe that a nodule has formed in your own thyroid gland, you can perform a thyroid neck check , as recommended by the American Association of Clinical Endocrinologists.5
Following a simple physical examination by a doctor, a blood sample is taken to determine whether the thyroid gland is functioning normally. An ultrasound scan will be performed to determine the size and features of the nodule. This scan is completely painless. Your doctor may also order additional investigations such as thyroid uptake scan or fine-needle aspiration biopsy depending on the clinical indication.9
Not every goitre or nodule requires treatment.1,7 Benign (non-cancerous) nodules may merely be observed. The need for treatment depends on the nature of the goitre or nodule, whether it is benign or cancerous, and if it causes symptoms.9 In general, there are three main treatment options: medication, radioactive iodine therapy and/or thyroid surgery.
If the goitre is due to Hashimoto’s thyroiditis and you have hypothyroidism based on symptoms and blood test, you will be given thyroid hormone replacement therapy to restore your thyroid hormone levels to normal.1 When goitres and nodules are accompanied by hyperthyroidism (e.g. as in the case with toxic thyroid nodules), treatment options include radioactive iodine, surgery or anti-thyroid medications.10
Radioactive iodine is used to destroy thyroid tissues that excessively produce thyroid hormones and shrink an enlarged thyroid gland or nodule.11 The radioactive iodine is administered on a one-off basis, in the form of a pill. Once swallowed, it enters the bloodstream and is taken up by the thyroid gland where it is stored — and uses short-range radiation to induce shrinkage of overactive thyroid tissues.10 This treatment is associated with risk of permanent hypothyroidism after treatment, requiring long-term thyroid hormone replacement therapy.
Another treatment for thyroid nodules involves partially or completely removing the thyroid gland via surgery. Surgery is recommended if a goitre or nodule has worrisome features of cancer or is causing immense discomfort because of its size.12 Patients who have had their whole thyroid gland surgery will require long-term thyroid hormone replacement therapy to replace the function of the thyroid gland.4
