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What are the common thyroid diseases?


Hyperthyroidism means you have too much thyroid hormone. This causes a range of problems for the body and these are described in our article on Graves' disease. As well as Graves’ disease hyperthyroidism can be caused by a thyroid adenoma – a small benign tumour in the thyroid gland that produces excessive thyroid hormones and by taking excessive amounts of thyroid hormone therapy. Treatment for hyperthyroidism involves having a single dose of radioactive iodine by mouth or by injection, taking anti-thyroid tablets regularly, or surgery. Many times all three methods are appropriate, while at other times a single treatment may be the best option.


Hypothyroidism means you have too little thyroid hormone. This causes many tissues to function abnormally. See our article on Hashimoto's disease. Hypothyroidism is common and the onset can be very slow so that you can have hypothyroidism for a number of years before it is recognised and treated. Hypothyroidism can also develop after treatment of hyperthyroidism, especially after surgery or radioactive iodine treatment. Congenital hypothyroidism is rare but important to detect and treat immediately. It is one of the conditions looked for in newborn screening programs in Australia. It may be due to a poorly developed thyroid gland or a normal-sized gland that does not produce enough thyroid hormones. Treatment for all types of hypothyroidism is usually straightforward and involves taking tablets of thyroid hormone regularly.

Thyroid cancer

Thyroid cancer is fairly uncommon. Most people who have thyroid cancer have excellent chances of surviving for a long time. For instance, in younger patients, with the most common forms of thyroid cancer there is a better than 95 per cent cure rate if the cancer is treated appropriately. There are five main types of thyroid cancer: papillary, follicular, medullary, anaplastic and thyroid lymphoma. Papillary and follicular cancers are the most common and are slow growing and usually straightforward to treat. Treatment may be monitored by measurement of the thyroid protein thyroglobulin in blood. Medullary thyroid cancer usually has a good outcome if it has not spread beyond the thyroid gland; it may produce excessive amounts of the hormone calcitonin, which can be used to monitor treatment. Anaplastic thyroid cancer is the least common but it is the most aggressive form and spreads quickly. It can be difficult to treat. Lymphoma, a tumour composed of lymphocytes (the cells that produce immunity from bacteria and viruses), can also occur in the thyroid.

Solitary thyroid nodule

A solitary thyroid nodule is a small lump on the thyroid gland. As many as 50 per cent of the population will have a nodule somewhere in the thyroid, however, the overwhelming majority of these nodules are harmless. Occasionally, thyroid nodules can be cancerous and need to be treated.


Thyroiditis is inflammation of the thyroid gland. It may be associated with either hypo- or hyperthyroidism. It may be painful, feeling like a sore throat, or painless. Thyroiditis may be due to an autoimmune disorder (especially Hashimoto’s thyroiditis), an infection, exposure to a chemical that is toxic to the thyroid, or due to an unknown cause (idiopathic). Depending on the cause, it can be acute but transient or chronic.


A thyroid goitre is a dramatic enlargement of the thyroid gland. This rarely happens in developed countries because iodine supplementation of some foods is common and this prevents severe iodine deficiency. Goitres are often removed for cosmetic reasons or because they compress other vital structures of the neck, including the windpipe (trachea) and the tube that leads from your mouth to your stomach, the oesophagus.

Last Review Date: April 1, 2017