The thyroid gland is situated in the front of the neck, and consists of two connected lobes, one on either side of the trachea (windpipe). Thyroid nodules are cystic (fluid-filled) or solid lumps that develop within the thyroid gland.
Thyroid nodules are very common. Using ultrasound they can be found in 25 per cent of people. They occur more frequently as people get older and in areas where dietary intake of iodine is poor. They are about 4 times more common in women than in men.
The vast majority of thyroid nodules are harmless, however a small proportion (about 5 per cent) are cancerous.
Most thyroid nodules do not cause any symptoms, and are often only discovered during a routine medical examination.
If nodules produce an excessive amount of thyroid hormone (‘hot’ nodules), they may cause symptoms of hyperthyroidism (over-active thyroid), such as fatigue, heat intolerance, weight loss and a rapid or irregular heart rate.
Occasionally, if nodules become quite large, they may put pressure on the trachea or oesophagus (gullet), causing symptoms such as difficulty with breathing or swallowing.
What tests are required?
Firstly, your doctor will carry out a full examination of the head and neck. A blood test to measure thyroid function will also be arranged.
In cases where the thyroid gland is overactive, the next step will usually be a nuclear medicine scan to look for ‘hot’ nodules.
Thyroid nodules are further assessed using ultrasound scanning. A biopsy using a fine needle will also be carried out on nodules that are large or suspicious. This involves inserting a small needle into the nodule to take a sample of cells for analysis.
Treatment will vary depending on the type of nodule. Your doctor will advise you as to the most appropriate treatment in your case.
Nodules that are suspicious for cancer require surgery. Large nodules that are putting pressure on underlying structures are also treated surgically.
‘Hot’ nodules are often treated by destruction with radioactive iodine or by surgical removal.
Nodules that are classified as benign by both biopsy and clinical assessment may be managed conservatively. This involves regular long-term follow-up by your doctor for clinical examination and periodic ultrasound scanning. However, if any new symptoms develop in between visits, these must be reported to the doctor.
Nodules that are growing are investigated by repeat biopsy and treated accordingly.
2. MJA Practice Essentials. 6. Thyroid nodules and thyroid cancer. Mackenzie EJ, Mortimer RH. https://www.mja.com.au/journal/2004/180/5/6-thyroid-nodules-and-thyroid-cancer (accessed Feb 2013).