A goitre (sometimes spelt "goiter") is an abnormal swelling of the thyroid gland that causes a lump to form in the neck.
There can be many possible causes, including an under- or overactive thyroid gland, iodine deficiency and, rarely, thyroid cancer.

The Thyroid Gland

The thyroid gland is a small butterfly-shaped gland in the neck, just in front of the windpipe (trachea). It produces thyroid hormones, which help regulate the body's metabolism (the chemical processes that occur in the body). The thyroid gland isn't usually noticeable, but if it swells, it produces a lump on the neck known as a goitre. The size of a goitre can vary from person to person. In most cases, the swelling is small and doesn't cause any symptoms. However, in more severe cases, the swelling can increase significantly and affect breathing and swallowing.

What causes a Goitre?

Goitres can have several possible causes, including:
an overactive thyroid gland (hyperthyroidism)
an underactive thyroid gland (hypothyroidism)
pregnancy and the menopause
a lack of iodine (a trace mineral found in milk and fish) in the diet
Read more about the causes of a goitre.

Diagnosing a Goitre

If you think you have a goitre, see a specialist – they can carry out some tests to determine whether you have one.
Your surgeon will examine your neck to see whether your thyroid gland is swollen. They may also refer you for a thyroid function test, to see how well your thyroid gland is working. A thyroid function test measures the level of certain hormones (chemicals produced by the body) in your blood. It can show whether you have an underactive or overactive thyroid, both of which are associated with goitre.

Treating a Goitre

The treatment for goitres depends on the underlying cause. If the goitre is small and isn't causing any problems, a wait-and-see approach is usually recommended.
Other possible treatments include radioiodine treatment and thyroid surgery.
Although most goitres are usually benign (non-cancerous), it's estimated that in 1 in 20 cases they may be a sign of thyroid cancer.