Guide to commonly used thyroid terms

Agranulocytocis: A disorder in the white blood cells that needs urgent treatment, caused by a reaction to an antithyroid drug.

Antibodies: Proteins in the blood that detect and destroy foreign bodies, such as viruses and bacteria. Auto-antibodies are antibodies that attack the body’s own tissues, such as thyroid cells, and cause Graves’ disease and Hashimoto’s thyroiditis.

Antithyroid drugs (ATD): The group of drugs called the thionamides, which include carbimazole and propylthiouracil, which suppress hormone manufacture by the cells in the thyroid gland.

Atrophic thyroid disease: A disease where the tissue is destroyed and the thyroid gland wastes away.

Autoimmune disorder: The body makes antibodies that attack its own normal cells and tissues, for example autoimmune thyroid disease and diabetes.

Autoimmune thyroid disease: The body makes antibodies that attack its own normal cells and tissues, for example Graves’ disease and Hashimoto’s thyroiditis.

Autoimmune thyroiditis: The most common form of hypothyroidism in which the body’s immune system attacks the thyroid cells as though they were foreign cells, leading to hypothyroidism. It is also known as Hashimoto’s thyroiditis.

Benign: Non malignant, or not cancerous.

Beta-blockers: Drugs that can help to relieve symptoms of hyperthyroidism, such as reducing palpitations and sweating.

Block and replace: Treatment for an over-active thyroid gland. Anti-thyroid drugs block the thyroid gland from producing any thyroxine. Then levothyroxine is given to replace natural thyroxine.

C Cell hyperplasia: An abnormal increase in the normal cells in an organ.

Calcium levels: Low levels can result from damage to the parathyroid glands during surgery, causing tingling in the hands and around the mouth. It is a condition known as ‘tetany’ and can be temporary or permanent.

Carbimazole: One of the anti-thyroid drugs used to treat an over-active thyroid. It stops the thyroid gland producing thyroid hormone.

Congenital hypothyroidism: Hypothyroidism that is present at birth.

Cyst: A lump, usually benign, that contains fluid.

Diabetes: Type I diabetes (insulin-dependent diabetes) usually occurs in young people. It is caused by antibodies destroying the cells in the pancreas that secrete the insulin.

Differentiated thyroid cancer: The cancer cells behave and look like normal thyroid cells. Papillary and follicular cancers are the most common types and are usually treated by surgery and radioactive iodine ablation.

Diffuse goitre: Where the entire thyroid gland swells and feels smooth to touch.

Dose titration: The dose is increased to a level that gives the optimal treatment.

Dyslexia: A learning difficulty related to reading and language skills.

Emla cream: A cream that numbs the skin and decreases the sensation of pain.

Endocrine gland: A gland that produce hormones.

Endocrinologist: A doctor specialising in diabetes and disorders of the thyroid, parathyroid and adrenal glands.

Endocrinology: The branch of medicine dealing with the endocrine glands and their secretions.

Fine needle aspiration cytology (FNAC): A test using a small needle that is passed into the thyroid gland to remove a small sample of tissue for examination.

Fine needle biopsy: A test using a small needle that is passed into the thyroid gland to remove a small sample of tissue for examination.

Follicular thyroid cancer: A less common type of differentiated thyroid cancer. About 20% of all differentiated thyroid cancers are follicular. The cells often look very similar to normal thyroid cells but can be a different shape.

Genetic testing: DNA-based tests used to test for genetic disorders.

Goitre: A swelling of the thyroid gland.

Graves' disease: An autoimmune condition that is the most common cause of an over-active thyroid in the UK. It is much more common in women than in men. It got its name from Robert Graves, an Irish physician who described patients with this condition in the 19th century.

Hashimoto's thyroiditis/Hashimoto's disease: Also known as autoimmune thyroiditis. This is the most common form of hypothyroidism. It is a disorder in which the body’s immune system attacks the thyroid cells as though they were foreign cells, leading to hypothyroidism.

Hashitoxicosis: A brief period of hyperthyroidism in a patient with Hashimoto’s disease.

Hormones: ‘Chemical messengers’ that affect how your cells and tissues work.

Hyperplastic nodules: Benign lumps which can be solitary or found in a multinodular goitre.

Hyperthyroidism: An over-active thyroid gland. The T4 and/or T3 are raised and the TSH is low.

Hypothyroidism: An under-active thyroid gland. The T4 level is low and the TSH level is high.

Isthmus: The bridge of tissue connecting the two lobes of the thyroid gland.

Larynx: Adam’s apple

Levothyroxine: A synthetic form of the thyroid hormone thyroxine (T4) contained in medication to treat an underactive thyroid gland.

Liothyronine: is a manufactured form of the thyroid hormone triiodothyronine (T3) and is sometimes used on the NHS to treat an underactive thyroid gland but only if initiated by, or considered appropriate following a review by, an NHS consultant endocrinologist.

Lobe: The thyroid gland consists of two lobes, the right and left lobe.

Lobectomy: Surgical removal of one side of the thyroid gland.

Lymph nodes: Glands that store cells that can trap cancer cells and bacteria

Medullary thyroid cancer: A rare type of cancer that can run in families. It arises from the C cells, which produce calcitonin. Calcitonin regulates calcium levels.

Metabolism: The speed at which the body’s cells work. The speed is controlled by the thyroid gland. If there is not enough thyroid hormone, the cells work too slowly; if there is too much thyroid hormone, the cells work too fast.

Multiple endocrine neoplasia (type 2) also known as MEN2: A group of medical disorders of the endocrine system. MEN2 typically includes medullary thyroid cancer, pheochromocytoma and/or primary hyperparathyroidism. It is also known as ‘Sipple Syndrome’.

Multinodular goitre (multiple thyroid nodules): is where the enlarged thyroid appears with a number of separate lumps (nodules) in the gland.

Newborn blood spot (Guthrie or heel prick) test: A blood test performed on newborn babies around a week after birth that is used to detect certain medical conditions, including hypothyroidism.

Natural Desiccated Thyroid (NDT): Is derived from porcine thyroid gland and contains both levothyroxine and liothyronine but in different ratios than those occurring in humans. It was the treatment used before levothyroxine was developed and is only available on a named patient basis on the NHS.

Nodule: A tissue or fluid-filled lump (on the thyroid or in the neck area). These can be ‘cold’ (thyroid function remains normal) or ‘hot’ (toxic) leading to suppressed TSH and raised levels of circulating T4 and T3.

Ophthalmologist: A doctor who specialises in the diagnosis and treatment of eye diseases.

Osteoporosis: Thinning of the bones that causes an increase in the risk and incidence of fracture. It is most common in post-menopausal women but also affects men and younger people.

Overactive thyroid gland (or hyperthyroidism): The condition arises when too much thyroxine is produced. The T4 and/or T3 are raised and the TSH is low. It can also result from too little treatment with an anti-thyroid drug or excessive treatment with levothyroxine.

Paediatric endocrinologist: A doctor who specialises in diseases of the endocrine (hormone) glands in children and young people.

Paediatrician: A doctor who specialises in the care of babies, children and young people.

Papillary thyroid cancer: The most common type of differentiated thyroid cancer. About 80% of differentiated thyroid cancers are papillary.

Parathyroid glands: Four very small glands about the size of a grain of rice lying very close to, and sometimes embedded in, the thyroid gland. They are responsible for controlling the level of calcium in your blood.

Pentagastrin stimulation test: A test in which gastric acid is stimulated.

Pituitary gland: A gland that controls the thyroid gland by releasing a hormone called thyroid stimulating hormone (TSH). The pituitary gland is found underneath your brain in your skull.

Precocious puberty: Puberty that occurs at an unusually early age.

Prophylactic: A treatment used to prevent a disease from occurring – for example a prophylactic total thyroidectomy is where the thyroid gland is removed to prevent medullary thyroid cancer.

Proptosis: Protruding or bulging eyes seen in thyroid eye disease.

Propylthiouracil: One of the antithyroid drugs that is used to treat an overactive thyroid.

Retrosternal goitre: Sometimes a multinodular thyroid grows down behind the breastbone causing constriction on the windpipe (trachea) and the large veins in the neck and/or the gullet (oesophagus). Most retrosternal goitres grow slowly over many years.

Radioactive iodine: Radioactive isotope of iodine, used to treat hyperthyroidism.

Radioactive iodine ablation (RAI): ‘Ablation’ literally means destruction. Radioactive iodine treatment destroys any remaining thyroid cells in the body after surgery.

Radiotherapy: treatment used in thyroid eye disease to reduce swelling.

Reference range: The range of values found in 95% of the healthy population and used in blood tests.

Steroids: Drugs used to relieve inflammation; they can be used for thyroid eye disease.

T3: Another term for triiodothyronine, one of the hormones made by the thyroid gland.

T4: Another term for thyroxine, one of the hormones made by the thyroid gland.

Tegaderm plasters: A sterile dressing that is easy to apply.

Thyroglobulin (Tg): Thyroid-binding protein found in blood that is monitored to detect any thyroid cancer recurrence; also known as a tumour marker.

Thyroglobulin antibodies (Tg Ab): Antibodies directed against the thyroglobulin (a protein present in the thyroid gland), from which thyroid hormones are produced. May be measured as part of the monitoring of people previously treated for thyroid cancer. Also sometimes raised in Hashimoto’s thyroiditis

Thyroid eye disease (TED): Eye disease associated with Graves’ disease.

Thyroid follicular adenoma: common, usually benign, lumps on the thyroid that are harder to distinguish from a cancer by scans and biopsy. It is, therefore, usually removed surgically so that its benign nature can be confirmed by close examination under the microscope.

Thyroid peroxidase antibodies (TPOAb): TPO is an enzyme that plays an important role in making thyroid hormones. Thyroid peroxidase antibodies develop when the immune system mistakes the components of the thyroid gland or its proteins as foreign. Raised in Hashimoto’s thyroiditis (or autoimmune thyroiditis) and sometimes raised in Graves’ disease

Thyroid stimulating hormone (TSH): Hormone secreted by the pituitary gland that regulates the hormonal output from the thyroid gland. Its measurement is used to confirm the diagnosis of hypothyroidism (raised TSH level) and of hyperthyroidism (depressed TSH level).

Thyroid stimulating hormone receptor antibodies (TSHR Ab, also known as TRAb): TRAb is potentially stimulatory and blocking to the thyroid gland and is raised in Graves’ disease.

Thyroid Stimulating Immunoglobulin (TSI): Antibody specific to Graves’ disease. It is a stimulatory antibody and the one that causes an overactive thyroid gland. TSI not routinely tested and used mainly as a research tool.

Thyroid cysts: This is a swelling that contains fluid, which is treated by removing the fluid through a needle (fine needle aspiration). If this fails, then surgery may be advised. A few centres across the UK have started to use ethanol injection into the cyst in order to avoid surgery.

Thyroid ultrasound scan: A technique for determining the structure of the thyroid, useful for investigating a goitre and may reveal a nodule or nodules that cannot be felt by a doctor, and show whether the lump is solid or filled with fluid.

Thyroxine (T4): One of the thyroid hormones, which contain four iodine atoms.

Total thyroidectomy: Total surgical removal of the thyroid gland.

Triiodothyronine (T3): A thyroid hormone, which contains three iodine atoms.

Underactive thyroid gland (or hypothyroidism): The T4 level is low and the TSH level is high.

Viral thyroiditis: An inflammation of the thyroid due to a virus, often not identified, which runs a variable course.

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