Glossary of Endocrinology
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Acanthosis nigricans - A gray or black discoloration of the skin usually seen in the neck, the underarms, and the groin. It is a sign of insulin resistance.
Acromegaly Acromegaly is a hormonal disorder where the pituitary gland produces excess amounts of growth hormone.
Addison's disease - A rare disease where the adrenal glands do not make enough cortisol and/or aldosterone (adrenal hormones). There are different causes of Addison's disease, but in many cases your body's immune system may not recognize the adrenal gland and try destroy it.
Adrenal Cortex The adrenal cortex is the outer portion of the adrenal gland and it produces steroid hormones, which regulate carbohydrate and fat metabolism, and mineralocorticoid hormones, which regulate salt and water balance in the body.
Adrenal Glands Adrenal glands are triangle-shaped glands that sit on top of the kidneys. They regulate stress response through the synthesis of hormones, including cortisol and adrenaline.
Adrenal insufficiency - A condition where the adrenal glands do not make enough cortisol and/or aldosterone (adrenal hormones).
Adrenocorticotropin (ACTH) Adrenocorticotropin is a hormone produced by the anterior pituitary gland that stimulates the adrenal cortex.
ACTH stimulation test - One of the laboratory tests used to diagnosis adrenal insufficiency.
Albumin Albumin refers to a group of relatively small proteins that are soluble in water and readily coagulated by heat.
Aldosterone - a hormone secreted by the adrenal cortex which affects blood pressure and saline balance.
Ambiguous Genitalia - A birth defect that causes a baby's genitals to look different from a typical boy or girl making it hard to tell the sex of the baby. (Additional lab and/or xray testing will be needed to confirm if baby is a boy or a girl.)
Amenorrhea - The lack of menstrual cycles in females. There are two types:
- Primary Amenorrhea: lack of first cycle or period after age 16 years.
- Secondary Amenorrhea: missed cycles or periods for longer than 6 months for girls of any age.
Amyloidosis - a rare disease which causes the buildup of amyloid, a protein and starch, in tissues and organs.
Androgens Androgens are hormones that help to develop sex organs in men. They also contribute to sexual function in men and women.
Andropause Andropause is a biological change characterized by a gradual decline in androgens experienced by men during and after their mid-life.
Antiandrogens – Antiandrogens are substances that inhibit the biological effects of androgenic hormones.
Antidiuretic hormone Antidiuretic hormones are secreted by the posterior pituitary gland. They regulate the amount of water excreted by the kidneys.
Antithyroid medications (Methimazole, Tapozole, and PTU) - This medication is used to treat any condition that causes too much thyroid hormone (Graves disease, thyroiditis). It lowers the amount of thyroid hormone produced by the thyroid gland.
Arginine Clonidine Growth Hormone Stimulation Tests - One of the laboratory tests used to diagnose growth hormone deficiency.
Arm span - A measurement of the distance between the middle fingertips of the left and the right hands when arms are spread out as far as possible. This measurement may be used to help your doctor identify growth disorders.
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Basal metabolic rate (BMR) - a measurement of energy required to keep the body functioning at rest. Measured in calories, metabolic rates increase with exertion, stress, fear, and illness.
Benign Prostatic Hyperplasia (Enlarged Prostate) – Benign prostatic hyperplasia is non-cancerous enlargement of the prostate gland, a common occurrence in older men.
Bioavailable testosterone Bioavailable testosterone represents the fraction of circulating testosterone that readily enters cells and better reflects the bioactivity of testosterone than does the simple measurement of serum total testosterone.
Bioidentical Hormones Bioidentical hormones are compounds that have exactly the same chemical and molecular structure as hormones that are produced in the human body. Though any hormone can be made to be "bioidentical," the term is often used to describe allegedly custom-compounded formulations containing estrogens, progesterone, and androgens. There is no evidence that they are any safer or more effective than FDA-approved hormone preparations.
Bone mineral density A bone mineral density (BMD) test measures the density of minerals (such as calcium) in bones using a special X-ray, computed tomography (CT) scan, or ultrasound. This information is used to estimate the strength of bones.
Bone age X-ray - An x-ray of the left hand and wrist. This x-ray may be a part of the growth evaluation. The doctor will compare the child’s chronological age (actual age) with their skeleton age (bone maturity). Delays or advancements in skeletal age from the child's actual age may help support an endocrine diagnosis.
Bromocriptine - a drug which acts on hormone-producing tumors to suppress its hormone-producing function.
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Calcitonin – Calcitonin is a protein hormone secreted by cells in the thyroid gland. It inhibits bone degradation and stimulates the uptake of calcium and phosphate by bone.
Cholesterol – Cholesterol is a white crystalline substance found in animal tissues and various foods that is normally synthesized by the liver. It is an important constituent of cell membranes and a precursor to steroid hormones.
Congenital Adrenal Hyperplasia – Congenital adrenal hyperplasia refers to a group of inherited adrenal gland disorders. People with this condition do not produce enough of the hormones cortisol and aldosterone, and produce too much of androgen. If CAH goes untreated, this condition can lead to death.
Constitutional delay of growth (late bloomer) - A normal variation of growth. A child will grow at a normal rate but appears smaller than children the same age. The bone age and the start of puberty are usually delayed. The child with constitutional delay of growth tends to have a catch up growth spurt at puberty reaching a normal adult height.
Corticosteroids - hormones produced by the adrenal gland, consisting of hydrocortisone and corticosterone.
Cortisol – Cortisol is a hormone produced by the adrenal gland. It is involved in the stress response and increases blood pressure and blood sugar levels.
Cushing's syndrome – Cushing's syndrome is a hormonal disorder caused by prolonged exposure of the body's tissues to high levels of the hormone cortisol. Sometimes called "hypercortisolism," it is relatively rare and most commonly affects adults aged 20 to 50.
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Desmopressin (DDAVP) - An oral medication that helps to lessen the amount of urine a person will make. This medicine is often used in patients with Diabetes Insipidus.
Diabetes – Diabetes is a disease in which blood glucose levels are above normal. The body of a person with diabetes either doesn't make enough insulin or can't use its own insulin as well as it should.
Diabetes Insipidus - This condition is a result of missing antidiuretic hormone (ADH). This hormone is made by the pituitary gland and helps the kidneys balance the fluid in the body. A person with this condition may have a large amount of urine each day and be very thirsty. If untreated, this condition can lead to dehydration, problems with growth, weight gain and appetite.
Dihydrotestosterone – Dihydrotestosterone is a male hormone more potent than testosterone that is converted from testosterone within the prostate.
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Endocrine Disruptor – Endocrine disruptors are natural and man-made chemicals that can either mimic or disrupt the action of hormones. Their impact on human biology is still unclear, but they have been implicated in a number of reproductive and health problems in animals.
Endocrinologist – An endocrinologist is a doctor that studies the glands and hormones of the body and their related disorders.
Epiphyseal plate (epiphyses) - The growing ends of the long bones, sometimes called the growth plate.
Erectile Dysfunction (ED) – Erectile dysfunction is a condition referring to the inability to achieve penile erection or to maintain an erection until ejaculation.
Estradiol – Estradiol, a type of estrogen, is a female sex hormone produced mainly by the ovaries. It is responsible for growth of breast tissue, maturation of long bones, and development of the secondary sexual characteristics.
Estrogen – Estrogens are a group of steroid compounds that are the primary female sex hormones. They promote the development of female secondary sex characteristics and control aspects of regulating the menstrual cycle.
Estrogen Therapy (ET) – Estrogen therapy is a hormone therapy treatment program in which women take estrogen orally, transdermally, vaginally or in a patch form to treat certain symptoms of menopause.
Florinef - A medication taken by mouth that helps replace the adrenal hormone, aldosterone.
Follicle stimulating hormone (FSH) – In women, FSH helps control the menstrual cycle and the production of eggs by the ovaries. The amount of FSH varies throughout a woman's menstrual cycle and is highest just before she ovulates. In men, FSH helps control the production of sperm.
Free Testosterone – Free testosterone is testosterone in the body that is biologically active and unbound to other molecules in the body, such as sex hormone binding globulin.
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Galactorrhea - Leaking of milk from the breast that can occur in both males and females who are not breastfeeding.
Genetic testing – Genetic tests are tests on blood and other tissue to find genetic disorders. About 900 such tests are available.
Glands – A gland is an organ in an animal's or human's body that synthesizes a substance for release such as hormones, often into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland).
Glucagon – Glucagon is a hormone involved in carbohydrate metabolism. Produced by the pancreas, it is released when the glucose level in the blood is low (hypoglycemia), causing the liver to convert stored glycogen into glucose and release it into the bloodstream.
Glycemia – Glycemia is the concentration of glucose in the blood.
Goiter - Enlargement of the thyroid gland which is located in the front of the neck, behind the trachea (wind pipe).
Gonads – A gonad is an organ that makes gametes (sperm and egg cells). The gonads in males are the testes and the gonads in females are the ovaries.
Gonadotropins – Gonadotropins are hormones that stimulate the growth and activity of the gonads, especially any of several pituitary hormones that stimulate the function of the ovaries and testes.
Gondadotropin releasing hormone (GnRH) – GnRH, also known as Luteinizing-hormone releasing hormone (LHRH), is a peptide hormone responsible for the release of gonadotropins from the anterior pituitary. GNRH is synthesized and released by the hypothalamus (an upper part of the brain).
Graves' Disease – Graves' disease is the most common form of hyperthyroidism. It occurs when your immune system mistakenly attacks your thyroid gland and causes it to overproduce the hormone thyroxine.
Growth failure - A term that your doctor might use when your child has not grown at a normal speed (growth velocity) for his/her age.
Growth Hormone – Growth hormone is secreted by the pituitary gland and stimulates growth of bone and essentially all tissues of the body by building protein and breaking down fat to provide energy.
Growth Hormone Replacement Therapy (Genotropin, Humatrope, Norditropin, Nutropin AQ, Saizen, Tev Tropin) -
A daily shot that is given for growth hormone deficiency or growth failure.
Gynecomastia – Gynecomastia is the development of abnormally large mammary glands (breast tissue) in males resulting in breast enlargement.
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Hirsutism – Hirsutism is excessive growth of thick dark hair in locations where hair growth in women usually is minimal or absent but typical in men, such as the face or chest.
Hormone – Made by endocrine glands, hormones are chemical messengers that travel in the bloodstream to tissues or organs. They affect many processes, including growth, metabolism, sexual function, reproduction, and mood.
Hormone therapy – Hormone therapy is the use of hormones in medical treatment. For example, doctors may use hormone therapy to boost estrogen levels in menopausal women. Other examples include thyroid hormone replacement for thyroid deficiency and insulin therapy for diabetes.
Hot flashes – Hot flashes refer to the sudden wave of mild or intense body heat caused by dilation of capillaries in the skin resulting from decreased levels of estrogen.
Hydrocortisone – Hydrocortisone also called cortisol, a hormone produced by the adrenal cortex upon stimulation by ACTH that mediates various metabolic processes (as gluconeogenesis), has anti-inflammatory and immunosuppressive properties, and whose levels in the blood may become elevated in response to physical or psychological stress.
Hyperinsulinism - Above normal levels of insulin in the blood of a person. It is the most common cause of low blood sugars seen in newborn babies. Hyperinsulism can also lead to decreased insulin sensitivity which may lead to high blood sugars. Treatment is aimed at keeping blood sugar levels normal and will be based on the cause of the condition.
Hyperparathyroidism - Overactive parathyroid gland causing too much calcium and low phosphorus levels in the blood. Calcium levels that are too high can cause weakness, dehydration, kidney stones, brittle bones, high blood pressure, seizures, or coma. Treatment is based on the cause of the condition.
Hyperprolactemia - An increase of the hormone prolactin secreted from the pituitary gland. An increased prolactin level can cause breast drainage (galactorrhea), irregular menstrual cycles, or enlarged breasts.
Hyperthyroidism - An increase in the production of thyroid hormone from the thyroid gland, which causes, trouble sleeping, diarrhea, tiredness, goiter, feeling hot, fast heart rate, weight loss, bulging of eyes, or shakiness. Treatment may include antithyroid medications and management of fast heart rates. In some cases radioactive iodine and/or surgery could be necessary.
Hypoglycemia – Hypoglycemia, also called low blood sugar, occurs when your blood glucose level drops too low to provide enough energy for your body's activities.
Hypogonadism – Hypogonadism is the condition in which the production of sex hormones and germ cells (sperm and eggs) is inadequate.
Hypopituitary - A condition resulting from decreased secretion of pituitary hormones.
Hypothyroid, Congenital - A condition found in 1 out of every 4000 newborns. All babies are tested for congenital hypothyroidism within the first week of life. When a baby has this condition, his/her thyroid gland is not producing enough hormone for the brain and body to grow and develop.
Hypothyroid, Acquired - A disorder that does not allow the thyroid gland to make enough thyroid hormone for the brain and body to grow and develop normally. Although, the condition is more common in teen girls, it can be found in boys and girls of any age.
Hypothalamus – The hypothalamus is an area of the brain that regulates vital autonomic centers and produces hormones that control thirst, hunger, body temperature, sleep, moods, sex drive, and the release of hormones from various glands, primarily the pituitary gland.
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Idiopathic Short Stature - Children presenting with <3rd percentile for height on standard growth chart. After evaluation by an endocrinologist, no medical conditions which cause growth failure are found. Patients may be candidates for growth hormone therapy.
Insulin – Insulin is a protein pancreatic hormone secreted by the beta cells of the islets of Langerhans that is essential especially for the metabolism of carbohydrates and the regulation of glucose levels in the blood and that when insufficiently produced results in diabetes mellitus.
Insulin Sensitizers – Insulin sensitizers make cells more responsive to insulin. They are commonly used in patients with type 2 diabetes.
Insulin Resistance - A condition the body needs more insulin than normal to control the blood sugar that increases a person’s risk of diabetes and heart disease. Usually associated with obesity.
Islets of Langerhans - pancreas cells that produce insulin and glucagon -- important regulators of sugar metabolism.
Isthmus - tissue that connects the two lobes of the thyroid.
IGF-1 – IGF-1, or insulin-like growth factor 1, is a polypeptide protein hormone similar in molecular structure to insulin. It plays an important role in childhood growth and continues to have anabolic effects in adults.
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Kallmann's syndrome – Kallmann's syndrome is form of hypogonadism that is caused by congenital gonadotropin-releasing hormone (GnRH) deficiency. It is more common in males.
Karyotype - A test that looks at the genetic make-up of a person. The test looks at the number, shape and size of the chromosomes (cell structures that carry DNA or genes). Extra, missing or abnormal chromosomes can explain problems with growth, and development.
Klinefelter's syndrome – Klinefelter's syndrome is the most common congenital abnormality in males causing primary hypogonadism, occurring in approximately 1 in 1000 live male births. This syndrome is the clinical manifestation of a male who has an extra X chromosome.
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Leuprolide Stim Test - Specialized blood test used for diagnosing early or delayed puberty. See leuprolide stim test.
Levothyroxine - Generic name for thyroid replacement hormone. Brand names may include Synthroid, Levoxyl.
Lupron Depot - A medication used to suppress puberty. Given by an injection or shot.
Luteinizing hormone – Luteinizing hormone—also known as lutropin—is necessary for proper reproductive function and in women it triggers ovulation.
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Menopause – Time of life when the ovaries stop making estrogen and the monthly (menstrual) periods stop.
Metabolism – Metabolism is the complete set of chemical reactions inside a cell. The metabolism of an organism determines what it find nutritious and the pace at which is converts nutrients to energy and how it stores excess nutrients.
Metabolic Syndrome – The term metabolic syndrome describes a cluster of metabolic risk factors that increase the chances of developing heart disease, stroke, and diabetes. Genetic factors, too much body fat, and lack of exercise add to the development of the condition.
Metformin - An oral medication that has been shown to improve the body's use of insulin. This medication is often used in patients with Type 2 Diabetes Mellitus, polycystic ovary syndrome and obesity. Brand name glucophage.
Methimazole - A generic name for Tapazole. Used as an anti-thyroid agent in the treatment of hyperthyroidism.
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Obesity – Obesity is typically defined as a body weight 30 percent over the ideal for a person's height, at which point it causes health conditions and leads to increased mortality.
Orchitis – Orchitis is a painful inflammation of the testicles and can lead to hypogonadism.
Osteoporosis – Osteoporosis is the diminishing of bone density, typically related to aging and menopause in women.
Ovaries – Ovaries are the egg producing organs found in females. They produce the hormones estrogen and progesterone
Oxytocin – Oxytocin is a hormone that acts as a neurotransmitter in the brain. It facilitates birth and breastfeeding.
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Pancreas – The pancreas secretes insulin, a hormone that helps glucose move from the blood into the cells where it is used for energy. The pancreas also secretes glucagon when the blood sugar is low.
Parathyroid – Located behind the thyroid gland are four tiny parathyroid glands. These make hormones that help control calcium and phosphorous levels in the body. The parathyroid glands are necessary for proper bone development.
Pineal Gland – The pineal is a small endocrine gland located in the center of the brain between the two hemispheres. It secretes melatonin, which helps regulate wake/sleep patterns.
Pituitary Gland – The pituitary is a small endocrine gland located at the base of the skull. It helps control growth, blood pressure, breast milk production, and metabolism.
Placebo – Placebo is an inactive ingredient or drug that is meant to appear like a genuine medicine. Placebos are often used in double blind studies as a control.
Polycystic Ovary Syndrome (PCOS) – Polycystic Ovary Syndrome (PCOS) is an endocrine disorder with a host of symptoms related to small painful cysts on the ovaries. It is marked by the overproduction of male hormones in females.
Prader-Willi syndrome – Prader-Willi syndrome is a genetic disorder that can cause a growth hormone deficiency. It is marked by a preoccupation with food, small stature, and learning difficulties.
Premature Adrenarche - The early growth of pubic hair before the age of 8 years in girls and the age of 9 years in boys.
Premature Thelarche - The early appearance of breast development in females who show no other signs of puberty.
Premenopause – Premenopause is the time in life when a woman gets monthly periods.
Premenstrual Syndrome – Premenstrual syndrome describes the appearance of physical and emotional symptoms during the second half of the menstrual cycle.
Progesterone – A female hormone that acts on the uterus (womb) to prepare it for receiving an egg following fertilization. When progesterone levels go down each month, this causes the bleeding associated with menstrual (monthly) periods.
Progestin – This is a synthetic form of progesterone. This class of drugs was originally developed to allow absorption by mouth for use in birth control pills.
Prolactin – Prolactin is a peptide hormone associate with lactation. High levels of estrogen during pregnancy stimulate its production.
PTU (Propylthiouracil) - A medication used to treat hyperthyroidism. This medicine slows or stops the thyroid gland from making too much thyroid hormone.
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Radioisotope scan - uses radioactive substances introduced into the body to create an image of the functioning adrenal gland.
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Sarcoidosis - a rare inflammation of the lymph nodes and other tissues throughout the body.
Sella turcica - bony structure that houses the pituitary gland.
Septo-optic dysplasia - A rare condition in which there is abnormal development in part of brain that can cause changes in a child's eyes and also problems in the pituitary gland.
Sex hormone binding globulin – Sex hormone binding globulin (SHBG) is a carrier protein that binds to the hormones testosterone and estradiol making them non-bioavailable.
Steroids – Steroids are any of various molecules—including hormones—that contain a particular arrangement of carbon rings. Some common steroids include sex steroids, corticosteroids, anabolic steroids, and cholesterol.
Suprarenal glands - another name for the adrenal glands.
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Tanner Stage - Medical term used for stages of puberty ranging on scale of 1-5.
Tapazole - A medication used to treat hyperthyroidism. This medicine slows or stops the thyroid gland from making too much thyroid hormone; also called methimazole.
Testes – Testes are the male reproductive organs. They produce sperm and the hormone testosterone.
Testosterone – Testosterone is a steroid, androgen hormone and the primary male sex hormone. It is produced by the testes in men and ovaries in women, and plays key roles in libido, energy, and immune function in both men and women.
Testosterone Replacement Therapy - This is a male hormone replacement medicine given either by applying to the skin every day or by a shot every 2 to 4 weeks in the muscle. This will help start puberty or maintain the male sex changes of adults.
Thymus – The thymus gland is located in the chest just behind the sternum. Hormones produced by this gland stimulate the production of certain infection-fighting cells, and plays a central role in the development of T cells.
Thyroid – The thyroid gland is located inside the neck. It regulates metabolism, which is the body's ability to break down food and convert it to energy. Thyroid disorders result from too little or too much thyroid hormone. Symptoms of hypothyroidism (too little hormone) include decreased energy, slow heart rate, dry skin, constipation, and feeling cold all the time.
Thyroid nodule - A lump or swelling felt in the neck in the area of the thyroid gland.
Thyroid scan - uses a radioactive substance to create an image of the thyroid as it is functioning.
Thyroid-stimulating hormone – Thyroid-stimulating hormone (TSH or thyrotropin) stimulates the thyroid to secrete the hormones thyroxine and triiodothyronine and is manufactured by the hypothalamus and transported by the Anterior Pituitary gland.
Thyroxine (T4) - a hormone secreted by the thyroid gland which regulates metabolism.
Total testosterone – Total testosterone the total amount of testosterone in the blood, combining free testosterone and testosterone bound to certain molecules and already at use in the body.
Triiodothyronine (T3) - a hormone secreted by the thyroid gland which regulates metabolism.
Transdermal delivery – Transdermal delivery is a method of delivering medications through the skin. It may be accomplished through patches that can be worn for varying lengths of time or as an ointment that can be applied manually.
Turner Syndrome – Turner syndrome occurs in females when one of the X (female) chromosomes is missing or damaged. The most common features of Turner syndrome are short stature and reduced or absent development of the ovaries. As adults, women with this disorder are typically infertile.
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Vitamin D – Vitamin D is a fat soluble vitamin that can be found in some foods but is mostly made by the skin when exposed to ultraviolet rays from the Sun. The two major forms are D2 and D3. Active vitamin D functions as a hormone because it sends messages to the intestines to increase the absorption of calcium and phosphorus. Vitamin D deficiency is known to cause several bone diseases, including rickets and osteoporosis.
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Water deprivation test - Test used to check the ability of kidneys to concentrate urine
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