What is the thyroid gland?
The thyroid gland is butterfly shaped and is located in front of the windpipe at the base of the neck. Next to the thyroid gland and adherent to it are the 2 laryngeal nerves that control the voicebox (one on each side of the thyroid gland). On each side of the thyroid gland there are also 2 tiny, pea-sized structures, called the parathyroid glands that control the regulation of the calcium in the body.
The thyroid gland weighs 10 to 20 g in normal adults and is responsible for the production of two families of metabolic hormones: the thyroid hormones thyroxine (T4) and triiodothyronine (T3) and the calcium-regulating hormone calcitonin. The thyroid gland is controlled by the brain in the form of 2 other hormones called TRH and TSH (hypothalamic-pituitary-thyroid axis).
The thyroid hormones are essential for the normal function of most of the human bodily functions. Thankfully, the function of the thyroid gland, which is to produce the thyroid hormones, can be replaced completely and without any consequences by a tablet that contains the same number of thyroid hormones.
Iodine is essential for normal thyroid function. The thyroid gland is responsible for storing 90% of total body iodide at any given time, with less than 10% existing in the extracellular pool.
Goitre is the presence of an enlarged thyroid gland and because of its large size it might cause pressure symptoms (difficulty with breathing, difficulty with swallowing and voice changes) and can be aesthetically unpleasant. Sometimes the goitre can extend inside the chest and in this case it is called retrosternal goitre. A surgical operation to remove the enlarged thyroid gland can offer a permanent cure for this condition.
Hyperthyroidism is the state in which there is an excess of thyroid hormones in the body and Thyrotoxicosis is the clinical manifestation of this condition.
Increased thyroid secretion can be caused by primary alterations within the gland (Graves’ disease, toxic nodular goitre, toxic thyroid adenoma) or central nervous system disorders and increased TSH-produced stimulation of the thyroid.
Thyroid surgery is the definitive and safe way of curing a patient from hyperthyroidism (once/if the alternative treatments which are antithyroid medication and/or radioactive iodine are no longer an option or contraindicated).
Thyroid cancer is a type of cancer that affects the thyroid gland and it is most common in people in their 30s and those over the age of 60.
Women are 2 to 3 times more likely to develop it than men. Thyroid cancer is usually treatable and, in many cases, can be cured completely, although it can sometimes come back after treatment.
Types of thyroid cancer
There are 4 main types of thyroid cancer:
- papillary carcinoma – the most common type, accounting for about 8 in 10 cases; it usually affects people under 40, particularly women
- follicular carcinoma – accounts for up to 1 in 10 cases and tends to affect middle-aged adults, particularly women
- medullary thyroid carcinoma – accounts for less than 1 in 10 cases; unlike the other types, it can run in families
- anaplastic thyroid carcinoma – the rarest and most serious type, accounting for around 1 in 50 cases; it usually affects people over the age of 60
Papillary and follicular carcinomas are sometimes known as differentiated thyroid cancers. They tend to be easier to treat than the other types.
Symptoms of thyroid cancer
Symptoms of thyroid cancer can include:
- a painless lump or swelling in the front of the neck – although only 1 in 20 neck lumps are cancer
- swollen glands in the neck
- unexplained hoarseness that does not get better after a few weeks
- a sore throat that does not get better
- difficulty swallowing
Treatments for thyroid cancer
Treatment for thyroid cancer depends on the type of thyroid cancer you have and how far it has spread.
The main treatments are:
- Surgery is the mainstay of the treatment of thyroid cancer and aims to remove part or all of the thyroid gland together with any affected lymph nodes (latter if required)
- Radioactive iodine treatment – you swallow a radioactive substance that travels through your blood and kills the cancer cells
- External radiotherapy – a machine is used to direct beams of radiation at the cancer cells to kill them
After treatment, you’ll have follow-up appointments to check whether the cancer has come back.
Thyroglossal duct cysts and fistulas, result from retained tissue along the thyroglossal duct.
Most thyroglossal duct cysts are found immediately beneath the hyoid bone and are noted in early childhood or infancy. These cysts are almost always in the midline and can be found from the base of the tongue to the suprasternal notch. They usually occur as a mass found in the midline on physical examination or when a localized infection occurs within that mass. A chronically infected or draining thyroglossal duct cyst can lead to a chronic draining fistula. For this reason, all thyroglossal duct cysts, on diagnosis, are treated surgically and excised because of their potential for infection.
The thyroglossal duct commonly passes through the center of the hyoid bone, thus requiring removal of the central portion of the structure. Occasionally, papillary cancer can occur in the thyroid tissue within the thyroglossal duct cyst, and complete removal of the tract is required.