AGRANULOCYTOSIS: A disorder in the white blood cells that needs urgent treatment, caused by a reaction to an anti-thyroid 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.

ANTI-THYROID 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.

DECOMPRESSION SURGERY: A procedure used in thyroid eye disease to create more space behind the eyes if there is pressure on the nerve, or if there is a lot of protrusion of the eyeballs in order to improve a person’s appearance.

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.

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.

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

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 which 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.

GUTHRIE TEST (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.

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.

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 under-active thyroid gland.

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’.

NODULE: A lump (on the thyroid or in the neck area).

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

OSTEOPOROSIS: Thinning of the bones which 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.

OVER-ACTIVE THYROID GLAND: 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 anti-thyroid drugs that is used to treat an over-active thyroid.

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.

THYROID EYE DISEASE (TED): Eye disease associated with 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 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.

UNDER-ACTIVE THYROID GLAND: 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.