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A1c (HbA1c): measure of average blood glucose (sugar) over the previous two to three months; determined by the amount of glucose bound to the hemoglobin in the red blood cells; used to diagnose diabetes and prediabetes and to monitor diabetes
ACE: see Adrenal cortex extract
ACTH: see Adrenocorticotropic hormone
Adenoma: benign tumor that arises in or resembles glandular tissue; an adenoma which becomes cancerous is called an adenocarcinoma
Addison’s Disease: failure of the adrenal glands, usually because of autoimmunity resulting in adrenal insufficiency; a life threatening disorder
Adrenals: glands located above each kidney that secrete hormones directly into the bloodstream
Adrenal cortex: outer part of the adrenals which exclusively manufactures corticosteroid hormones – cortisone, hydrocortisone and aldosterone – and manufacturers other hormones which are also made elsewhere including testosterone, estrogen, DHEA, 17-hydroxy-ketosteroids, pregnenolone,  androstenedione, progesterone and others
Adrenal cortex extract (ACE): over-the-counter dietary supplement containing extract of usually bovine adrenal cortex; used to support adrenal function
Adrenal medulla: inner part of the adrenals which manufactures adrenaline (epinephrine) and noradrenaline (norepinephrine)
Adrenaline (epinephrine): "fight or flight" hormones released in potentially life-or-death situations which increase heart rate and blood pressure and divert extra blood to brain, heart and skeletal muscles; may be used as a substitute for cortisol for some processes when available cortisol is insufficient
Adrenocorticotropic hormone (ACTH): primary stimulator of adrenal cortisol production, synthesized by the pituitary in response to corticotropin-releasing hormone (CRH), released by the hypothalamus
Adult-onset diabetes: see Diabetes Mellitus, type 2
Aldosterone: corticosteriod  produced in the the adrenal cortex with mineralocorticoid properties; involved in the balance of potassium and sodium, and therefore fluid balance as well
Androstenedione (Andro): androgenic steroid produced by the testes, adrenal cortex and ovaries; it is converted to testosterone and other androgens and is the precursor of estrone
Androsterone: by-product created during the breakdown of androgens or derived from progesterone
Anemia: condition of having lower-than-normal number of red blood cells or hemoglobin; see also Iron deficiency anemia
Anemia of chronic disease: also called anemia of inflammatory response; sufficient iron is available in the body but is sequestered into ferritin to deny access to it by harmful pathogens; serum iron will be low and transferrin or TIBC will also be low; hemoglobin may be low; supplementing iron can be dangerous
Antibody: an immunoglobulin (specialized immune protein) produced because of the introduction of an antigen into the body, and which possesses the ability to combine with the antigen that triggered its production; antibodies can be triggered by and directed at foreign proteins, microorganisms or toxins; some antibodies are autoantibodies and attack the body's own tissues as in Hashimoto's Thyroiditis
Antigen (abbreviation of antibody generator; Ag): any substance that causes the immune system to produce antibodies against it; may be a foreign substance from the environment (e.g., chemicals, bacteria, viruses, pollen) or inside the body (e.g. bacterial toxins or tissue cells)
Apoferritin: ferritin that does not contain iron
Autoimmune: pertaining to autoimmunity
Autoimmunity: a misdirected immune response when the immune system attacks the body itself; present to some extent in everyone and usually harmless but can cause a broad range of conditions, known collectively as autoimmune diseases; autoimmune diseases occur when there is progression from benign autoimmunity to pathogenic autoimmunity determined by genetic influences and/or environmental triggers; evidenced by the presence of autoantibodies (antibodies directed against the person who produced them) and T cells that are reactive with host antigens
Basal body temperature: the lowest body temperature (usually occurring during sleep) measured immediately after awakening and before rising; identified by Dr. Broda Barnes as useful to evaluate thyroid status; frequently used to determine ovulation for fertility
Blood-brain barrier: tight cell-to-cell contact that prevents many substances from leaving the blood and crossing the capillary walls into brain tissue
Blood glucose: the amount of a certain sugar, glucose, measured in blood serum
Bradycardia: see heart rate
C-peptide: byproduct of insulin production, usually by the pancreas; its level is a gauge of how much insulin is being produced
Calcitonin: polypeptide hormone especially from the thyroid gland that tends to lower the level of calcium in blood plasma; also synthetic form of calcitonin used to treat postmenopausal osteoporosis and Paget's disease of bone
Chronic Lymphocytic Thyroiditis: see Hashimoto's Thyroiditis
Circadian rhythm: internal biological clockof about 24 hours common to humans, animals, plants, fungi and cyanobacteria of about 24 hours, and adjusted by environmental cues such as daylight
Congenital: condition that is present at birth, whether or not it is inherited
Cortef®: see Hydrocortisone
Corticosteroid: substance produced by the adrenal gland categorised as glucocorticoid or mineralocorticoid; see glucocorticoid and mineralocorticoid
Corticosteroid binding globulin (CGB; Cortisol Binding Globulin, Transcortin): protein which binds 75 to 80 percent of the cortisol produced by the adrenal cortex. It also binds progesterone, aldosterone and 11-deoxycorticosterone. Also called Cortisol Binding Globulin
Cortisol: glucocorticoid produced by the zona fasciculata of the adrenal cortex, in response to stimulation by ACTH; functions include increasing blood glucose through gluconeogenesis; suppressing the immune system; aiding fat, protein and carbohydrate metabolism; also refers to its bio-identical pharmaceutical, hydrocortisone
Cortisone (11-dehydrocorticosterone): produced naturally in small amounts by the adrenal cortex, it is a precursor to cortisol and also a product of cortisol inactivation
Corticotropin-releasing hormone (CRH): hormone made by the hypothalamus that stimulates the release of corticotropin by the anterior pituitary gland (see also Adrenocorticotropic Hormone)
CRH: see Corticotropin-releasing Hormone
Cynomel®: see T3
Cytomel®: see T3
DHEA: See Dehydroepiandrosterone
Dehydroepiandrosterone (DHEA): steroid hormone produced in the adrenal cortex from cholesterol; the primary precursor of estrogens. Also known as dehydroandrosterone and dehydroisoandrosterone.
Deiodinase: see Iodothyronine Deiodinase
DHT: see Dihydrotestosterone
Diabetes: technically refers to any of various abnormal conditions characterized by the secretion and excretion of excessive amounts of urine; however, most often refers to diabetes mellitus, the forms of diabetes which cause blood glucose to rise to unhealthy levels
Diabetes Insipidus: disorder caused by insufficient secretion of vasopressin by the pituitary gland or by a failure of the kidneys to respond to circulating vasopressin; characterized by intense thirst and the excretion of large amounts of urine; may result from partial or complete failure of the kidneys to respond to vasopressin or from damage (injury, infection,disease) to the pituitary gland or hypothalamus
Diabetes Mellitus: a disorder of carbohydrate metabolism caused by a combination of hereditary and environmental factors and usually characterized by inadequate secretion or utilization of insulin, excessive urine production, excessive amounts of sugar in blood and urine; see type 1 and type 2
Diabetes Mellitus, type 1: usually develops during childhood or adolescence and is characterized by a severe deficiency of insulin secretion resulting from atrophy of the islets of Langerhans in the pancreas; causes hyperglycemia and a marked tendency toward ketoacidosis; may be characterized by thirst, hunger and loss of weight
Diabetes Mellitus, type 2: common form of diabetes that develops especially in adults and often in obese individuals characterized by hyperglycemia resulting from impaired insulin utilization (insulin resistance) coupled with the body's inability to compensate with increased insulin production
Dihydrotestosterone (DHT): metabolite of testosterone produced in the adrenal cortex which binds more strongly than testosterone to androgen receptors
ELISA: acronym for Enzyme Linked Immuno-Sorbent Assay, a method of blood testing used particularly for immunoglobulin antibodies
Epinephrine: see adrenaline
Ferritin: a globular iron storage protein which keeps iron in a soluble and non-toxic form
Gland: group of cells that secrete a substance for use in the body (e.g., the thyroid gland)
Glucocorticoid: corticosteroid which affects glucose production; also any pharmaceutical with glucocorticoid affect (hydrocortisone, prednisone, methylprednisone, dexamethasone)
Glucose tolerance test: test of the body's ability to metabolize glucose (sugar); involves fasting administration of a measured dose of glucose and measure of glucose levels in the blood and/or urine at specific intervals; used especially to diagnose diabetes mellitus
Glycohemoglobin: seeA1c
Goiter: noncancerous enlargement of the thyroid gland; levels of thyroid hormones may be normal, elevated (hyperthyroidism), or decreased (hypothyroidism)
Goitrogen: substances, including certain isoflavones in some foods and certain drugs (e.g., lithium and phenylbutazone), that can cause enlargement of the thyroid gland (see Goiter) due to interference with the production of thyroid hormone; generally occurs only with accompanying iodine deficiency; can be aggravated by selenium deficiency; goitrogens found in food appear to be inactivated by thorough cooking
Graves' Disease: autoimmune condition causing a hyperthyroid state; often characterized by goiter and slight protrusion of the eyeballs
Hashimoto's Thyroiditis (Chronic Lymphocytic Thyroiditis): autoimmune condition in which the immune system attacks the thyroid gland; most common cause of hypothyroidism in the United States; occurs much more often in women than men and increases in frequency of occurrence with age
Heart rate (pulse): number of heartbeats per unit of time, usually per minute; based on the number of contractions of the ventricles (the lower chambers of the heart); may be too fast (tachycardia) or too slow (bradycardia)
HbA1c: see Glycohemoglobin
Hemochromatosis: iron disorder, usually inherited, causing excess absorption of iron; left untreated, the resulting excess iron can damage joints, organs, and eventually be fatal
Homeostasis: maintaining balance of various body processes achieved in humans by functions of the liver, kidneys, hypothalamus, autonomic nervous system and endocrine system
Hormone: chemical substance produced in the body that controls and regulates the activity of certain cells or organs; many hormones are secreted by special glands, such as thyroid hormone produced by the thyroid gland; hormones are essential for every activity of life, including the processes of digestion, metabolism, growth, reproduction and mood control; many hormones, such as neurotransmitters, are active in more than one physical process
HPA axis (hypothalamo-pituitary-adrenocortical axis): a feedback mechanism of the neuro­endocrine system among the hypothalamus, the pituitary gland and the adrenal glands; controls the body’s response to stress and regulates digestion, the immune system, energy use and storage, emotions, mood and sexuality
Hydrocortisone: bioidentical pharmaceutical cortisol (brand names Cortef®, Hysone®)
Hyperglycemia: condition of excess glucose in the blood
Hyperkalemia: condition of excess potassium
Hypernatremia: condition of excess sodium
Hypertension: high arterial blood pressure, generally systolic blood pressure of 140 mm Hg or greater and/or diastolic blood pressure of 90 mm Hg or greater; typically results in a thickening and inelasticity of arterial walls and hypertrophy of the left heart ventricle
Hyperthyroidism: excessive functional activity of the thyroid gland; also the resulting condition characterized by increased metabolism, rapid heart rate, enlargement of the thyroid gland and high blood pressure (see Graves' Disease)
Hypoglycemia: condition of insufficient glucose in the blood
Hypokalemia: condition of insufficient potassium
Hyponatremia: condition of insufficient sodium
Hypotension: abnormally low blood pressure
Hypothalamus: almond-sized part of the brain which synthesizes and secretes neurohormones to stimulate or inhibit secretion of pituitary hormones controlling body temperature, hunger, thirst, fatigue, sleep and circadian cycles; responds to both internal and external stimuli
Hypothyroidism: deficient activity of the thyroid gland; also the resulting condition characterized by lowered metabolism and general loss of energy
Hysone®: see hydrocortisone
Insulin: hormone synthesized in the pancreas from secreted by the beta cells of the islets of Langerhans; essential for the metabolism of carbohydrates, lipids and proteins; regulates blood glucose levels by facilitating uptake of glucose into tissues, promoting its conversion into glycogen, fatty acids and triglycerides, and by reducing the release of glucose from the liver
Insulin resistance: reduced sensitivity to insulin, resulting in an increase in insulin production and an increase of hyperglycemia; typical of type 2 diabetes and occurs as a precursor to diabetes
Insulin-dependent Diabetes, Insulin-dependent Diabetes Mellitus: see Diabetes Mellitus, type 1
Insomnia: perception or complaint of inadequate or poor-quality sleep due to factors such as difficulty falling asleep, waking up frequently during the night with difficulty returning to sleep, waking up too early in the morning, or unrefreshing sleep
Iodide: chemical form to which iodine in the diet is reduced before it is absorbed through the intestinal wall into the bloodstream and carried through the blood to the thyroid gland
Iodine: element in the diet that is essential for the manufacture of hormones by the thyroid gland;  found primarily in seafood, bread, iodized salt and seaweed (see also Iodide)
Iodothyronine deiodinase:  enzymes (D1, D2, D3) that modify the biological activity of thyroid hormone either activating T4 (type II deiodinase, D2) or inactivating T4 and T3 (type III deiodinase, D3) at the cellular level; activity not generally reflected in serum hormone levels
Iron deficiency anemia: anemia that is caused by a deficiency of iron
Juvenile Diabetes, Juvenile-onset Diabetes: see Diabetes Mellitus, type 1
Late-onset Diabetes: see Diabetes Mellitus type 2
Levothroid®: see T4
Liothyronine: see T3
Lupus: chronic inflammatory disease that is caused by autoimmunity; patients with lupus have in their blood unusual antibodies that are targeted against their own body tissues; Lupus can cause disease of the skin, heart, lungs, kidneys, joints and nervous system
Medrol: see Methylprednisone
Metabolic: relating to metabolism; often refers specifically to the breakdown of food and its transformation into energy
Metabolism: the whole range of biochemical processes that occur within a living organism; consists of anabolism (the buildup of substances) and catabolism (the breakdown of substances); often used as a term for the processes which produce energy
Methylation: biochemical process where a methyl group is added to DNA to turn genes on and off
Methylprednisone: medium acting synthetic glucocorticoid
Mitochondria: small organelles within each cell which convert energy into forms that are usable by the cell for its activities; involved in other cell processes such as division, growth and death; mitochondria have their own DNA and reproduce independent of the cell; inherited almost exclusively from the mother
MTHFR: Methylenetetrahydrofolate reductase enzyme involved in folate metabolism; also the gene responsible for producing the enzyme
Natural desiccated thyroid: see Thyroid hormone extract
NDT: see Thyroid Hormone Extract
Nodule: small (usually 1 to 2 cm diameter) collection of tissue that can be felt at any level of the skin (in the epidermis, dermis, or subcutis) or in another tissue of the body such as the thyroid gland
Non-insulin-dependent Diabetes: see Diabetes Mellitus type 2
Orthostasis: see Orthostatic Hypotension
Orthostatic hypotension: (also postural hypotension or orthostasis) condition of blood pressure dropping on standing
Pituitary: pea-size endocrine gland located at the base of the brain which secretes nine hormones that regulate homeostasis; secretions are regulated by the Hypothalmus (see HPA axis)
Postural hypotension: see Orthostatic hypotension
Prednisone (also Prednisolone): medium-acting synthetic glucocorticoid
Pulse: see Heart Rate
Radioactive iodine: isotope of the chemical element iodine that is radioactive; used in diagnostic tests as well as in radiotherapy of a hyperactive thyroid gland (hyperthyroidism) most often due to Graves' disease
Receptor (in cell biology): structure on the surface of a cell or inside a cell that selectively receives and binds a specific substance
Renin: enzyme which participates in the body's renin-angiotensin system (RAS) that mediates extracellular volume (i.e., that of the blood plasma, lymph and interstitial fluid) and arterial vasoconstriction
Renin–angiotensin-aldosterone system: physiological system that regulates blood pressure through renin, involved in the conversion of angiotensinogen into angiotensin I; angiotensin-converting enzyme (ACE) then converts angiotensin I into angiotensin II, which stimulates the secretion of aldosterone, which in turn stimulates salt and water reabsorption by the kidneys and the constriction of small arteries, which increases blood pressure
Reverse T3 (RT3): inactive thyroid hormone converted from T4 and which contains three atoms of iodine
Synthroid®: see T4
T3: liothyronine (also triiodothyronine); the active thyroid hormone containing three atoms of iodine; refers to the natural hormone produced by the thyroid gland and converted throughout the body from T4 and/or to exogenous hormone contained in thyroid hormone extract and available as a bioidentical pharmaceutical liothyronine sodium or triiodothyronine (brand U.S. Cytomel®, Mexico Cynomel®, U.K., Australia Tertroxin®)
T4: tetraiodothyronine sodium (also levothyroxine or thyroxine); inactive thyroid hormone produced by the thyroid gland which contains four atoms of iodine and/or exogenous hormone contained in thyroid hormone extract and available as a synthetic pharmaceutical compound (brand names Synthroid®, Levothroid®, Levoxyl®, Unithroid®, Tirosint®)
Tachycardia: see Heart Rate
Tertroxin®: see T3
Thyroid: a small, butterfly shaped endocrine system gland  located at the base of the throat which produces thyroid hormones; also used to refer to hormone itself
Thyroid binding globulin (TBG): proteins synthesized mainly in the liver which carry thyroid hormones; androgens, glucocorticoids and malnutrition can decrease TBG; high estrogen levels can raise it
Thyroid hormone: any of the substances produced by the thyroid gland, primarily T4 (so called due to containing four molecules of iodide) and a small amount of T3 (so called due to containing three molecules of iodide) which is also converted from T4 losing one iodide molecule in the process; little is known about T2 and T1 (containing two and one molecules of iodide, respectively) which function as precursors and byproducts of thyroid hormone synthesis and are generally believed to be inert; calcitonin is also produced by the thyroid
Thyroid hormone extract: (natural desiccated thyroid, NDT) dried extract of thyroid gland usually porcine (sometimes bovine) used as replacement thyroid therapy; UPS standardized
Thyroid hormone resistance: (1) in endocrinology: a relatively rare syndrome in which thyroid hormone levels are elevated but the thyroid stimulating hormone (TSH) level is not suppressed, or not completely suppressed as would be expected, and some tissues have resistance to thyroid hormone; caused by genetic defect in the thyroid hormone receptors (2) in general usage: a condition where thyroid hormone levels appear normal in testing, while hypothyroid symptoms indicate hormones are not being utilized at a cellular level; may be due to high reverse T3, elevated sex hormone binding globulin, or other unknown causes
Thyroid stimulating hormone (TSH; also called Thyrotropin): hormone produced by the pituitary gland that stimulates production of thyroid hormone; produced in response to signals from the hypothalamus gland
Thyroid storm: a sudden life-threatening increase of symptoms of hyperthyroidism (e.g.,high fever, tachycardia, increase in metabolism, weakness and/or extreme restlessness) brought on by various causes (infection, surgery, stress)
Thyrotoxicosis: see Hyperthyroidism
Thyrotropin: see Thyroid sttimulating sormone
Tirosint®: see T4
Triiodothyronine: see T3
-tropin: suffix indicating "an affinity for”.
Transcortin: see Corticosteroid binding globulin
TSH: see Thyroid stimulating hormone
Type 1 Diabetes: see Diabetes Mellitus, type 1
Type 2 Diabetes: see Diabetes Mellitus, type 2
Tyrosine: amino acid necessary as a precursor to production of thyroid hormone
Unithroid®: see T4