The thyroid gland is located at the base of the neck, and is comprised of two lobes (on each side of the windpipe), joined together by an isthmus.
The thyroid gland produces thyroxine (a thyroid hormone), which is important in regulating the metabolic rate of tissues and cells.
An overactive thyroid gland (hyperthyroidism) produces too much thyroxine and causes symptoms of tremor, palpitations, nervousness, poor sleep, weight loss, and heat intolerance.
An under active gland (hypothyroidism) causes the opposite type of symptoms due to a slowing of the metabolic rate. This may result in fatigue, weakness, weight gain, depression, cold intolerance, and dry rough skin.
A goitre is simply an enlarged thyroid gland. There are many possible causes, including:
A goitre may require removal for cosmetic reasons, but it may also cause compressive symptoms due to pressure on the trachea and oesophagus, making breathing and swallowing difficult.
Thyroid nodules are very common. Up to 50% of the population may have a nodule somewhere in their thyroid gland. A nodule is a lump in an otherwise normal gland, and the vast majority of these are benign.
The nodule may represent an overgrowth of normal thyroid tissue, or a cyst containing fluid. Ultrasound scans can be helpful in determining the characteristics of the nodule and whether there is a single or multiple nodules.
Fine needle aspiration (FNA) is also helpful in determining whether there is any cancer within the nodule.
Surgery may be indicated if the enlarged thyroid gland is causing symptoms, or if there is doubt about the diagnosis and malignancy is a concern.
Thyroid cancer is relatively common and fortunately has an excellent long term survival.
The majority of thyroid cancers are papillary and follicular cancers.
Although they may spread to lymph nodes or more distant sites in the body, they are very treatable and have a good prognosis.
Thyroid surgery may be required for excision of a goitre, thyroid nodules or thyroid cancer.
The type of surgery depends on the diagnosis and extent of disease.
This may involve removal of half (hemithyroidectomy) or the whole thyroid gland (total thyroidectomy), and sometimes the lymph nodes in the neck if there is cancerous involvement.
If the whole gland is removed, thyroid replacement tablets must be taken daily, for the rest of the patient's life.
There are small but significant risks involved with thyroid surgery. In particular there is a small risk of damage to a nerve which runs very close to the thyroid gland as it passes to the larynx (voice box).
Damage to this nerve results in a change in voice which is usually temporary but can be permanent. This is extremely rare, and if it happened the voice can be improved by a small operation.
There is also a risk of damage to the parathyroid glands (four small glands which lie just behind the thyroid gland). This is not a significant risk with a hemithyroidectomy as there are 2 normal glands on the other side. With total thyroidectomy it is possible that the blood supply to these glands will be interrupted.
These glands help maintain calcium levels in the blood, and so calcium levels will be checked following surgery and temporary or permanent calcium replacement may be required.
There are other possible complications of thyroid surgery which will be discussed fully pre–operatively.