The thyroid gland is found at the centre of the neck (figure 1). It is a butterfly-shaped gland that hugs the trachea (windpipe) and is responsible for producing thyroxine, a hormone that regulates metabolism and hence crucial to a person’s well-being.
Common Thyroid Problems
The thyroid gland is prone to several distinct conditions, some of which are very common. The conditions that affect the gland can be divided into problems concerning (1) hormone production, (2) increased growth of the gland causing compression of important structured in the neck or just presenting as a lump in the neck, (3) formation of discrete lumps or nodules within the gland tissue, raising the fear of cancerous growths (4) cancer of the thyroid gland.
How do you know if a neck lump is from the thyroid gland?
Most thyroid lumps are found in the middle or just off centre in the neck (figure 2). And since the thyroid gland hugs the trachea which moves upwards on swallowing, a thyroid lump will move on swallowing too.
How do we investigate a thyroid lump?
If the patient presents with symptoms of excessive or inadequate production of thyroxine, blood tests will confirm the diagnosis. If the problem is a discrete lump (nodule), a fine needle aspiration (FNA Figure 3) will determine the nature of the nodule in about 95% of patients. This is the most useful test for discrete thyroid nodules. It is performed in the clinic and takes less than a minute to complete. An ultrasound of the gland is usually ordered to determine if the nodule is solitary or part of a multinodular gland and to look for features that may suggest malignancy eg. microcalcifications, enlarged neck glands.
What is the management for thyroid lumps?
If the problems concerns thyroxine production, an endocrinologist will be best person to treat that problem. If the main symptom is a nodule and the function of the thyroid gland is normal, then an ENT surgeon will be able to decide the best treatment for the lump.
When is surgery recommended?
Surgery is usually recommended when the issue is Cosmetic (unsightly neck lump), Compression (shortness of breath, difficulty swallowing) and Cancer. The extent of gland removal will be dependent on the indication for surgery.
Thyroid surgery is generally straightforward. The main risks depend on whether half the gland is removed (hemithyroidectomy) or the whole gland is removed (total thyroidectomy) and includes
1. Recurrent Laryngeal Nerve Injury – the recurrent laryngeal nerve runs behind the two lobes of the thyroid gland to enter the voice box above. It is generally easy to find and preserve. However, if the nerve is stretched during surgery, the patient will experience temporary hoarseness which fully recovers over time. The risk of permanent nerve damage and hoarseness in experienced hands is less than 1%.
2. Hypocalcemia – this means low serum calcium levels. The complication is only seen in total thyroidectomy. Calcium metabolism is regulated by parathyroid hormone which is produced by the parathyroid glands. There are 4 glands, two on each side and found on the back side of the thyroid gland. If only half the thyroid gland is removed, the calcium levels will not be affected because the two parathyroid glands that are not touched on the unoperated side will be sufficient to maintain normal calcium levels. However, if the whole gland is removed, then all the parathyroid glands will be traumatized and the patient will experience a temporary fall in calcium levels that require monitoring in hospital.
3. Bleeding – as in any surgery, bleeding can occur. In rare instances, bleeding can be profuse and require emergency evacuation of blood clots.
Some facts on Thyroid Nodules
- Most thyroid nodules are benign. The incidence of benign nodules increases with age.
- Thyroid cancer can affect any age group. Most occur after the age of 30. Its aggressiveness increases significantly in older patients
- Hoarseness, rapidly increasing nodule, painful and hard nodules and associated enlarged neck glands are suggestive of malignant disease.
- The majority of thyroid cancers have a good to excellent prognosis if treated appropriately.
Some facts on Thyroid Cancer
- Women are prone to thyroid cancer than men.
- There are 4 types; Papillary (most common), Follicular, Medullary and Anaplastic
- Papillary and Follicular types are well-differentiated and associated with a better prognosis than the other two.
- Anaplastic carcinoma is most aggressive and invariably fatal within a year of diagnosis. It generally affects elderly patients.
- Staging of thyroid cancer is depending on the AGES scoring;
- Age (less than 40 years is good)
- Grade (well-differentiated is good)
- Extracapsular spread, which means the cancer spreading beyond the capsule (covering) of the thyroid gland (this is bad) and
- Size (less than 4cm in diameter is good)
MBBS (S'pore), FRCS (Edin), FRCS (Glasg) Fellow, Otology / Neurotology (Can)
NUH ENT Conference Jan 2005