Endocrinology is a complex science. Much of the terminology used in the study of growth, growth disorders, and human growth hormone therapy may be unfamiliar to you. So we've put together a glossary to help acquaint you with these terms and concepts.
adolescence: The teenage years; the physical and mental transition from child to adult (see puberty).
adrenal glands: Located above the kidneys in the lower back, these two glands produce several kinds of hormones.
adult growth hormone deficiency (AGHD): Growth hormone deficiency during adulthood. Adults need growth hormone to maintain healthy body composition and metabolism. AGHD occurs when the pituitary gland either is missing or does not secrete enough growth hormone. It may be the continuation of a growth hormone deficiency that began in infancy or childhood (childhood-onset AGHD), or it may begin in adulthood (adult-onset AGHD).
adult-onset AGHD: Adult growth hormone deficiency that begins in adulthood.
AGHD: See adult growth hormone deficiency.
amino acids: The building blocks of proteins that determine their shape and function.
androgen: A type of natural or artificial steroid that acts as a male sex hormone.
bone age: The stage of development or maturity of the bones. In most children, bone age will be about the same as chronological (actual) age, but in some children it may be advanced (ahead) or delayed (behind). It is measured by taking an X-ray, usually of the hand and wrist, to look at the bones and compare them with standards for boys and girls of various ages.
centile or percentile: A number based on dividing something into 100 parts—in this case, a group of children of the same age. The centile number tells what percentage of children of that age are taller or shorter than the child being measured.
centimeter (cm): A metric unit of measurement for length. 1 cm = 0.4 inches; 2.54 cm = 1 inch.
childhood-onset AGHD: Adult growth hormone deficiency that begins in infancy or childhood.
chondrodystrophies: Conditions involving abnormal development of the cartilage (tissue that develops into bone); sometimes called skeletal dysplasias (conditions involving abnormal development of bones).
chromosomes: Microscopic bodies inside cells. Chromosomes carry the genes that convey hereditary characteristics.
deficiency: A lack of something; in the case of endocrine deficiency, not enough of a hormone.
endocrine system: The system of glands in the human body that are responsible for producing hormones.
endocrinology: The branch of medicine dealing with the endocrine system and its hormones.
estrogen: A female sex hormone, also present in small quantities in males. Estrogen stimulates secondary sexual characteristics in women (for example, the development of breasts) and also helps bones to grow.
genes: Chemical units inherited from parents. Genes determine the specific characteristics of offspring.
genetic: Describing features or conditions of the body that are the result of heredity—the passing-down of traits from parent to child through genes.
gland: An organ or a specialized group of cells in the body that produces secretions, such as insulin or bile, or excretions, such as sweat.
growth hormone (GH): See human growth hormone.
heredity: The passing-down of traits from parent to child through genes, which are located in chromosomes. Such traits are said to be "inherited."
hormones: Chemicals secreted into the bloodstream in small amounts by glands located throughout the body. Hormones "set in motion" many life processes—growth, puberty, reproduction, and metabolism.
human growth hormone (hGH or GH): A hormone secreted by the pituitary gland that, in children, causes physical growth. In adults as well as children, hGH is essential to maintain healthy body composition and metabolism (in other words, to improve one's ratio of fat to lean body mass). Also known simply as growth hormone or somatotropin.
hypogonadism: A condition in which sex organs such as the testes or ovaries are underactive.
hypothyroidism: A condition in which the thyroid gland is underactive.
idiopathic: Occurring without a known cause.
insulin-like growth factor I (IGF-I, somatomedin): A chemical produced by the liver and other tissues in response to human growth hormone (hGH). It plays a role in helping hGH cause changes in cells that lead to growth.
kilogram (kg): A metric unit of measurement for weight. 1 kg = 2.2 pounds; 0.45 kg = 1 pound.
malnutrition (malnourishment): Poor nourishment resulting from insufficient food, improper diet, etc.
metabolism: The chemical and physical processes continuously occurring in the body and its cells, such as when foods are turned into energy, tissue, or waste products.
ovaries: The female sex organs that produce eggs and secrete the female sex hormone estrogen.
pediatric growth hormone deficiency (PGHD): Growth hormone deficiency during infancy or childhood. PGHD occurs when the production of growth hormone by the pituitary gland is disrupted. This results in abnormalities of many body processes, including growth and development, production of muscle protein, and breakdown of fats. Although PGHD is uncommon, it may occur at any time during infancy or childhood, and there are many possible causes.
percentile: See centile.
PGHD: See pediatric growth hormone deficiency.
pituitary gland: A small gland attached by a stalk to the base of the brain; it secretes hormones that control other glands and regulate growth. It is sometimes called the "master gland."
proteins: Compounds that are found throughout the body and serve many important functions. They are the main components of cells. Growth hormone and IGF-I are examples of proteins.
puberty: The time of life when the greatest amount of growth occurs and the development of sexual characteristics (such as pubic hair, breasts in females, and lower voice in males) takes place.
somatotropin: Another name for human growth hormone.
syndrome: A set of features or symptoms often occurring together and believed to stem from the same cause.
synthesize: To create something, such as chemicals in the body, from simpler, raw materials.
testes: The male sex organs that secrete the male sex hormone testosterone.
testosterone: A male sex hormone, also present in small quantities in females. Testosterone stimulates secondary sexual characteristics in men (for example, deepening of the voice), accelerates growth, and affects metabolism.
thyroid gland: A large gland situated in front and on either side of the trachea (windpipe) that secretes the hormone thyroxine, which helps regulate body growth and metabolism.
