Glossary

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Acropachy 
"Clubbing" of the fingers with thickening of skin at the base of the nails, often with an increase in the curvature of the nails. Acropachy is very occasionally seen in patients with Graves' disease. 

Adenoma 
A benign tumor on an endocrine gland, such as a thyroid adenoma 

AIDS 
Acquired immunodeficiency syndrome 

Ambidexterity 
Partial left-handedness 

Amiodarone 
A heart drug that contains a large amount of iodine. Amiodarone can cause abnormal thyroid function 

Anaplastic cancer 
A very rare, but malignant form of thyroid cancer. 

Antigen 
Any substance that has the capacity to induce an immune response 

Antigen-presenting cell 
A cell involved in the immune process 

Antiperoxidose (antimicrosomal) antibody 
Antibody directed against peroxidose, a protein located in tiny particles known as microsomes within thyroid cells 

Antithyroid Drugs 
Medications that slow the thyroid gland's production of thyroid hormone. 

Apathetic hyperthyroidism 
A type of thyroid overactivity seen in elderly patients, with so few symptoms and signs that the thyroid problem is often unrecognised 

Artifical tears 
Eyedrops used to lubricate dry eyes 

Attention deficit disorder 
A type of learning disability in which the individual has difficulty concentrating on particular tasks 

Autoantibody 
Antibody directed against one's own tissues 

Benign 
Non-cancerous 

Beta-adrenergic receptors 
Receptors on the cell surface that bind adrenaline, a hormone that can cause rapid heartbeat, tremor, and nervousness. 

Beta-blockers 
A class of drugs that block "beta-adrenergic receptors" and are capable of diminishing many symptoms of thyroid-hormone excess. Propranolol, atenolol, metoprolol, and nadolol are all beta-blocking drugs. 

Biliary cirrhosis 
A condition in which bile flow is impeded, leading to liver damage 

Bipolar disease 
A form of depression in which the mood cycles between exhilaration and depression 

Bone-density test 
A test that evaluates the calcium content of bone, used to diagnose osteoporosis 

Calcitonin 
A hormone made by the abnormal C cells detected easily in small quanitities for early diagnosis of medullary thyroid cancer 

Carpal tunnel syndrome 
A neurological condition in which compression of an important nerve at the wrist (the median nerve) may cause hand weakness, numbness, and pain 

Cassava 
A plant that has a high level of thiocyanate, which cause goiter, especially in areas of the world where there is also iodine deficiency 

CAT scan 
A special X ray procedure, sometimes used to evaluate the size or location of the thyroid, thyroid eye problems, or thyroid tumors. 

Chernobyl 
Site of the 1986 nuclear accident in the Ukraine 

Click murmur 
A sound commonly caused by mitral valve prolapse 

Cold nodule 
A nonfunctioning thyroid lump that does not concentrate radioactive isotopes in a thyroid scan. 

Cretinism 
Permanent physical and mental impairment due to severe thyroid deficiency in early life. 

Crohn's disease 
A disease in which the small intestine is inflamed 

Curie 
A measure of radiation. 

Cytokine 
A type of protein hormone involved in the immune process 

Cytoplasm 
The part of a cell surrounding the nucleus 

Cytotoxic 
Having the ability to destroy another cell. 

Diffuse Toxic Goiter 
The general cause of Graves' disease. 

Dulse 
Seaweed 

Echocardiogram 
A heart test in which ultrasound is used to study the anatomy and function of the heart. 

Electromyogram (EMG) 
A test done to evaluate muscle function 

Endemic hypothyroidism 
A place where thyroid deficiency is commonly found, often due to iodine deficiency. 

Exophthalmos 
Protrusion of the eyes in Graves' disease 

Fallout 
Radioactive material that falls from the sky after a nuclear accident contaminating the environment, including crops and water supplies. 

Fine needle aspiration 
A type of thyroid biopsy using a very thin needle 

Follicular cancer 
A common form of thyroid cancer usually curable with thyroid surgery. 

Free thyroid hormone level 
Active or "unbound" hormone that reacts with body tissues 

Generalized resistance to thyroid hormone (GRTH) 
A condition in which body cells respond subnormally to thyroid hormone, due to abnormal thyroid hormone receptors 

Goiter 
Enlargement of the thyroid; either diffuse (general enlargement) or nodular (asymmetric growth). 

Goiter belt 
Part of the midwestern United States surrounding the Great Lakes where iodine-deficiency goiter was a common occurrence until the introduction of iodized salt in the mid-1920s. 

Goitrogen 
A substance that may cauase the thyroid to enlarge, forming a goiter. 

Graves' disease 
A form of hyperthyroidism caused by a diffuse toxic goiter. Often associated with the exophthalmos of the eyes. 

Hashimoto's disease 
An autoimmune form of thyroiditis which often causes a goiter and results in hypothyroidism. Usually treated with thyroid hormone replacement. 

Hot Nodule 
An lump in the thyroid gland which draws more iodine on a scan than normal thyroid tissue. Often involved in hyperthyroidism, hot nodules are very rarely cancerous. 

Human chorionic gonadatropin (HCG) 
A placental hormone that helps maintain pregnancy in the early months of gestation. 

Hürthle cell cancer 
A form of thyroid cancer 

Hyperthyroidism 
When an excess in thyroid hormone produces the symptoms of abnormally high metabolism. Either caused by an overactive thyroid gland, hot nodule, or taking too much thyroid hormone replacement. 

Hypothyroidism 
When the body's metabolism is too slow due to absence or deficiency of thyroid hormone. Either due to an abnormal thyroid gland or taking an inadequate level of thyroid hormone replacement. 

Hyperparathyroidism 
When the parathyroid gland produces too much hormone (parathyroid hormone or PTH). Can cause calcium deposits, osteoporosis, or nervous system complaints. 

Immunoglobulin 
Proteins that function as antibodies 

Interferon gamma 
A protein able to inhibit viral activity. 

Interleukin-1 (IL-1) 
A protein induced by macrophages and T cells in an immune reaction 

Iodine 
An element commonly found in seafood and in most commercially produced salt. Iodine is the most necessary ingredient in thyroid hormone. 

Isthmus 
The connecting piece of thyroid tissue between the left and right lobes of the thyroid gland. 

Larynx 
The part of the trachea which contains the vocal cords. 

Lithium 
A metal commonly used in oral antidepressants to treat manic depression. Lithium has been known to interfere with the production of thyroid hormone and can cause goiter. 

Lupus Erythematosis 
An immune disease in which antibodies are made to many different types of body cells. 

Lymphocytic hypophysitis 
Inflammation of the pituitary gland 

Macrophage 
A scavenger cell that is very important in activating the immune system. 

Major histocompatibility complex (MHC) 
Cell-membrane receptors that bind to antigens and thus help initiate immune reactions. 

Malignant 
Cancerous 

Median nerve 
An important nerve supplying sensation and strength to the hand. The nerve that is compressed in carpal tunnel syndrome. 

Medulla 
The central part of a gland. 

Medullary cancer 
A type of thyroid cancer involving a specialized type of thyroid cell known as the C cell because it manufactures calcitonin. Medullary cancer may be hereditary. 

Methimazole 
An antithyroid medication used to treat hyperthyroidism. 

Mitral Valve Prolapse (MVP) 
A heart condition due to improper closure of one of the heart valves. 

Multi-Nodular Goiter 
Enlarged thyroid with two or more nodules. 

Multiple sclerosis 
An autoimmune inflammatory condition of the nervous system. 

Neonatal hyperthyroidism 
Overactivity of the thyroid in a newborn 

Neoplasm 
A tumor or growth, whether benign or malignant. 

Nodule 
A lump or abnormal growth on the thyroid, whether benign or malignant. 

Nonsteroidal anti-inflammatory drug (NSAID) 
A group of drugs that reduce inflammation. Examples are Advil (ibuprofen), Motrin, Naprosyn, and Indomethacin. 

Nucleus 
The central part of the cell that contains genetic material that controls cell functions. The nucleus also contains the thyroid-hormone receptor. 

Oncogene 
A gene found in all cells that may help convert normal cells to cancer cells 

Oophoritis 
Inflammation of the ovaries. 

Orbital decompression 
Eye surgery involving removal of part of the bony orbit to reduce eye protrusion. 

Osteoporosis 
A condition characterized especially by bone loss from the hip and spine, with increased risk for fractures. A common occurrence in older men and women, but can also be associated with hyperparathyroidism. 

Palpitation 
When, due to irregular beats or the heart beating faster or more forcefully than normal, you can feel your heart beat. 

Papillary cancer 
The most common form of thyroid cancer, usually curable by surgery. 

Parathyroid 
Four glands usually located behind the thyroid that control calcium and bone metabolism. 

Periodic paralysis 
Intermittent, partial, or total loss of strength due to shifts in potassium into cells rarely seen in Graves' disease, especially in Asian men. 

Petechiae 
Small red spots due to tiny haemorrhages within the skin. 

Pituitary Gland 
A small gland located at the base of the brain which secretes hormones that control other glands including the thyroid. Produces thyroid stimulating hormone the levels of which are the most diagnostic in identifying a thyroid disorder. 

Platelets 
Small blood cells that have an important role in blood clotting. 

Postpartum depression 
Depression after pregnancy. 

Postpartum thyroiditis 
Thyroid inflammation occurring after pregnancy. 

Potassium iodide 
A drug used to treat certain thyroid disorders. It can also be used to block the uptake by the thyroid of radioactive-iodine isotopes that are released in a nuclear-reactor accident. 

Propylthiouracil (PTU) 
An antithyroid medication which is used to limit the thyroid gland's ability to produce thyroid hormone. 

Radioactive Iodine (RAI) 
A radioactive isotope of iodine used in the diagnosis and treatment of thyroid growths and cancers. 

Radioisotope 
A radioactive substance that emits specific kinds of radiation. Radioisotoptes of iodine are used for thyroid scans and thyroid therapy. 

Raynaud's syndrome 
A disorder caused by spasm of tiny arteries in the hands and feet often brought on by cold temperatures. 

Receptor 
A special site on the cell surface or within the cell where specific chemicals, especially hormones, bind and initiate a variety of actions within the target cell. 

Regional enteritis 
A synonym for Crohn's disease. 

Schirmer test 
A test done to evaluate tearing of the eyes 

Scleroderma 
An immune disorder affecting many parts of the body including particularly the skin and the intestine. 

Selenium 
A trace element used by thyroid cells that may help protect against diseases due to iodine deficiency. 

Silent thyroiditis 
Painless thyroiditis 

Sjögren's syndrome 
An immune condition leading to a decreasing in tearing, saliva production, and vaginal secretions. 

Subclinical hyperthyroidism 
Mild thyroid overactivity unaccompanied by obvious symtoms or physical signs. 

Substernal goiter 
A goiter located under the breastbone. 

T cell 
A type of lymphocyte involved in cellular immunity. 

- Helper T cell 
A lymphocyte involved in cellular immunity. 

- Suppresser T cell 
A lymphocyte that tends to decrease immune activity. 

- Killer T cell 
Lymphocytes that can destroy invading antigenic cells or normal body tissues in certain autoimmune diseases. 

- Natural killer cell 
Lymphocytes that can destroy invading antigenic cells or normal body tissues in certain autoimmune diseases. 

- Cytotoxic T cell 
Lymphocytes that can destroy invading antigenic cells or normal body tissues in certain autoimmune diseases. 

Thiocyanate 
A chemical found in some foods that may interfere with thyroid function. 

Three Mile Island 
Site of a minor nuclear accident in Pennsylvania. 

Thrombocytopenic purpura 
A condition in which platelets are reduced in number and that may lead to bleeding disorders. 

Thyroglobulin 
A protein in the thyroid in which thyroid hormones are manufactured and stored. Some thyroglobulin is secreted into the blood stream and can be used as a marker for the presence of thyroid disease, especially cancer. 

Thyroiditis 
Inflammation of the thyroid. There are several forms of thyroiditis, including chronic or Hashimoto's thyroiditis, subacute thyroiditis, and painless or postpartum thyroiditis. 

Thyroid Stimulating Hormone (TSH) 
A hormone produced by the pituitary gland which controls the thyroid gland's production of thyroid hormones (T3 and T4). The test of TSH levels is generally regarded as the most sensitive test to identify thyroid disorders. 

Thyroxine (T4) 
The primary hormone produced by the thyroid gland. Naturally formed from iodine molecules, this hormone is available in animal and synthetic forms as replacement when the thyroid produces little or no thyroxine itself. 

Triiodothyronine (T3) 
Another hormone produced by the thyroid gland, more potent than thyroxine (T4). Generally produced by the breakdown of T4, sometimes a person cannot do this naturally and then must take a synthetic form of T3. 

Tumor 
A mass of tissue, whether benign or malignant. 

Ulcerative colitis 
An illness in which the large intestine (colon) becomes inflamed. 

Vitiligo 
A patchy loss of pigment on the skin associated with thyroiditis and autoimmune diseases