Med Term Section 14

thyroid-stimulating hormone

(TSH) stimulates the secretion of hormones by the thyroid gland

pituitary adenoma

is also known as a pituitary tumor. There are two types of these slow-growing benign tumors of the pituitary gland. Functioning pituitary tumors often produce hormones in large and unregulated amounts. Nonfunctioning pituitary tumors do not produce excessive amounts of hormones.

Exophthalmos

is an abnormal protrusion of the eyeball out of the orbit (ex- means out, ophthalm/o means eye and -s is a noun ending).

Aldosteronism

is an abnormality of the electrolyte balance that is caused by the excessive secretion of aldosterone.

Hyperglycemia

is an abnormally high concentration of glucose in the blood (hyper- means excessive, glyc means sugar, and -emia means blood condition). Hyperglycemia is seen primarily in patients with diabetes mellitus. The symptoms include polydipsia, polyphagia, and polyuria. Hyperglycemia is the opposite of hypoglycemia.

Hypoglycemia

is an abnormally low concentration of glucose (sugar) in the blood (hypo- means deficient, glyc means sugar, and -emia means blood condition). Symptoms include nervousness and shakiness, confusion, perspiration, or feeling anxious or weak. Hypoglycemia is the opposite of hyperglycemia.

drenocorticotropic hormone

(ACTH) stimulates the growth and secretions of the adrenal cortex (adren/o means adrenal, cortic/o means cortex, trop means change, and -ic means pertaining to).

antidiuretic hormone

(ADH), which is secreted by the hypothalamus and stored in the pituitary gland, helps control blood pressure by reducing the amount of water that is excreted through the kidneys (see Chapter 9). In contrast, a diuretic is administered to increase the amount of urine secretion.

Aldosterone

(ALD) is a corticosteroid that regulates the sodium and water levels in the body by increasing sodium reabsorption and potassium excretion by the kidneys. Reabsorption means returning a substance to the bloodstream.

certified diabetes educator

(CDE) is a health care professional qualified to teach people with diabetes how to manage their disease.

Diabetes insipidus

(DI), which is not related to diabetes mellitus, is an uncommon disorder caused by an insufficient production of the antidiuretic hormone ADH or by the inability of the kidneys to respond appropriately to this hormone. When there is an insufficient quantity of ADH, too much fluid is excreted by the kidneys. This causes polydipsia (excessive thirst) and polyuria (excessive urination) that in extreme cases can reach over 20 quarts a day. If this problem is not controlled, it can cause severe dehydration. Insipidus comes from a Latin word meaning without taste, referring to the relatively low sodium (salt) content of the urine in patients with diabetes insipidus.

Diabetes mellitus

(DM), the most common endocrine system disease, is a group of metabolic disorders characterized by hyperglycemia resulting from defects in the body's production of insulin (type 1) or its ability to use it properly (type 2). Diabetes mellitus is not related to diabetes insipidus.

Estrogen

(E) is a hormone secreted by the ovaries that is important in the development and maintenance of the female secondary sex characteristics and in regulation of the menstrual cycle.

Epinephrine

(Epi, EPI), also known as adrenaline,stimulates the sympathetic nervous system in response to physical injury or to mental stress such as fear. It makes the heart beat faster and can raise blood pressure. It also helps the liver release glucose and limits the release of insulin.

follicle-stimulating hormone

(FSH) stimulates the secretion of estrogen and the growth of ova (eggs) in the ovaries of the female. In the male, it stimulates the production of sperm in the testicles (testes).

Glucagon

(GCG) is the hormone secreted by the alpha cells of the pancreatic islets in response to low levels of glucose in the bloodstream. Glucagon increases the glucose level by stimulating the liver to convert glycogen into glucose for release into the bloodstream. (Note: Glucagon and glycogen are similar words, and the prefixes gluc/o and glyc/o both refer to glucose or sugar. It may help to remember that glucagon is a hormone secreted in the pancreas, and glycogen is excess carbohydrate stored in the liver.)

growth hormone

(GH), also known as the somatotropic hormone, regulates the growth of bone, muscle, and other body tissues (somat/o means body, trop means change, and -ic means pertaining to).

Conn's syndrome

(KON) is a disorder of the adrenal glands that is caused by the excessive production of aldosterone. This disease, which is a form of primary aldosteronism, can cause weakness, cramps, and convulsions.

luteinizing hormone

(LH) stimulates ovulation in the female. In the male, the luteinizing hormone stimulates the secretion of testosterone.

lactogenic hormone

(LTH), also known as prolactin, stimulates and maintains the secretion of breast milk in the mother after childbirth (lact/o means milk, gen means producing, and -ic means pertaining to).

melanocyte-stimulating hormone

(MSH) increases the production of melanin in melanocytes, thereby causing darkening of skin pigmentation (see Chapter 12). MSH production usually increases during pregnancy.

Oxytocin

(OXT) stimulates uterine contractions during childbirth (oxy- means swift, and -tocin means labor). After childbirth, oxytocin controls postnatal hemorrhage and stimulates the flow of milk from the mammary glands. Pitocin is a synthetic form of oxytocin that is administered to induce or speed up labor.

parathyroid hormone

(PTH), which works with the hormone calcitonin that is secreted by the thyroid gland. Together, they regulate the calcium levels in the blood and tissues. Higher-than-normal levels of parathyroid hormone can increase calcium levels in the blood by mobilizing the release of calcium stored in bones and teeth.

Radioactive iodine treatment

(RAI) is the oral administration of radioactive iodine to destroy thyroid cells. This nuclear medicine procedure, which disables at least part of the thyroid gland, is used to treat thyroid cancer and chronic hyperthyroid disorders such as Graves' disease. For more information on nuclear medicine, see Chapter 15.

radioactive iodine uptake test

(RAIU) uses radioactive iodine administered orally to measure thyroid function. The amount of radioactivity in the thyroid is measured 6 to 24 hours later using a handheld instrument called a gamma probe.

Syndrome of inappropriate antidiuretic hormone

(SIADH) is caused by the overproduction of the antidiuretic hormone ADH. This is often as a result of cancer or its treatment. High amounts of ADH keep the kidneys from excreting water, resulting in bloating and water retention that can dilute the blood, causing electrolyte imbalances, particularly hyponatremia (low levels of sodium).

pinealoma

is a tumor of the pineal gland that can disrupt the production of melatonin (pineal means pineal gland, and -oma means tumor). This tumor can also cause insomnia by disrupting the circadian cycle.

pancreas

a feather-shaped organ located posterior to the stomach that functions as part of both the digestive and the endocrine systems

Hemoglobin A1c testing

also known as HbA1c, pronounced as "H-B A-one-C," is a blood test that measures the average blood glucose level over the previous 3 to 4 months. (Note: The name of this test is sometimes shortened to A1c.)

fasting blood sugar test (FBS)

also known as a fasting plasma glucose test, measures the blood glucose levels after the patient has not eaten for 8 to 12 hours. This test is used to screen for diabetes as well as to monitor treatment of this condition.

thyroid storm

also known as a thyrotoxic crisis, is a relatively rare, life-threatening condition caused by exaggerated hyperthyroidism. Patients experiencing a thyroid storm may complain of fever, chest pain, palpitations, shortness of breath, tremors, increased sweating, disorientation, and fatigue.

Hypothyroidism

also known as an underactive thyroid, is caused by a deficiency of thyroid secretion (hypo- means deficient, thyroid means thyroid, and -ism means condition). Symptoms include fatigue, depression, sensitivity to cold, and a decreased metabolic rate.

Hashimoto's disease

also known as chronic lymphocytic thyroiditis, is an autoimmune disease in which the body's own antibodies attack and destroy the cells of the thyroid gland. This inflammation often leads to hypothyroidism.

Cortisol

also known as hydrocortisone, is a corticosteroid that has an anti-inflammatory action. It also helps regulate the metabolism of carbohydrates, fats, and proteins in the body.

Cushing's syndrome

also known as hypercortisolism, is caused by prolonged exposure to high levels of cortisol. Cortisol has an anti-inflammatory action and helps regulate the metabolism of carbohydrates, fats, and proteins in the body. Signs of Cushing's syndrome include a rounded, red "moon" face

Goiter

also known as thyromegaly, is an abnormal, benign enlargement of the thyroid gland (thyr/o means thyroid, and -megaly means abnormal enlargement). This enlargement produces a swelling in the front of the neck. A goiter usually occurs when the thyroid gland is not able to produce enough thyroid hormone to meet the body's needs, either due to Graves' disease, other medical conditions, or an iodine deficiency.

Hyperthyroidism

also known as thyrotoxicosis, is the overproduction of thyroid hormones (hyper- means excessive, thyroid means thyroid, and -ism means condition), which causes an imbalance of metabolism. This causes symptoms including an increased metabolic rate, sweating, nervousness, and weight loss. The most common cause of hyperthyroidism is Graves' disease.

Steroids

are a large family of hormone-like substances that share the same fat-soluble chemical structure. Examples of steroids include cholesterol, testosterone, and anti-inflammatory corticosteroids such as prednisone. steroids are secreted by endocrine glands or artificially produced as medications to relieve swelling and inflammation in conditions such as asthma.

gonads

are gamete-producing glands. These are ovaries in females and testicles in males. The gonads secrete the hormones that are responsible for the development and maintenance of the secondary sex characteristics that develop during puberty. Secondary sex characteristics refer to features that distinguish the two sexes but are not directly related to reproduction. The additional functions of the gonads are discussed in Chapter 14.

Thyroid nodules

are lumps in the thyroid that can grow large enough to cause a goiter (see Graves' disease later in the chapter). Most nodules are benign; however, some are malignant or produce too much thyroxine.

Anabolic steroids

are man-made substances that are chemically related to male sex hormones. They are used in the treatment of hormone problems in men and to help the body replace muscle mass lost due to disease. Athletes sometime use anabolic steroids illegally to build muscle mass, a dangerous practice that can lead to lasting damage to the body.

Electrolytes

are mineral substances—calcium, chloride, magnesium, phosphorus, sodium, and potassium—that are normally found in the blood and other bodily fluids.

Neurohormones

are produced and released by neurons in the brain, rather than by the endocrine glands, and delivered to organs and tissues through the bloodstream. One example is neurohormones secreted by the hypothalamus that control the secretions of the pituitary gland

Androgens

are sex hormones secreted by the gonads, the adrenal cortex, and fat cells.

Androgens

are sex hormones, primarily testosterone, secreted by the gonads, the adrenal cortex, and fat cells. Androgens promote the development and maintenance of the male sex characteristics.

Corticosteroids

are the steroid hormones produced by the adrenal cortex. The same term describes synthetically produced equivalents that are administered as medications.

pancreatic islets

are those parts of the pancreas that have endocrine functions. An islet is a small isolated mass, or island, of one type of tissue within a larger mass of a different type.

Gigantism

is abnormal growth of the entire body that is caused by excessive secretion of growth hormone before puberty. Contrast with acromegaly.

Latent autoimmune diabetes

in adults (LADA), also known as Type 1.5 diabetes, is a condition in which type 1 diabetes develops in adults. It shares many of the characteristics of type 2 diabetes; however, autoimmune antibodies are present. Latent means present but not visible. LADA usually occurs in adults with a normal weight and family history of type 1 diabetes. It is estimated that at least 10% of adults with diabetes have LADA. It is treated with diet, exercise, oral medications, and insulin.

melatonin

influences the sleep-wakefulness portions of the circadian cycle. The term circadian cycle refers to the biological functions that occur within a 24-hour period.

insulinoma

is a benign tumor of the pancreas that causes hypoglycemia by secreting additional insulin (insulin means insulin, and -oma means tumor).

prolactinoma

is a benign tumor of the pituitary gland (pro- means on behalf of, lactin means milk, and -oma means tumor). This type of tumor, which causes the pituitary gland to produce too much of the lactogenic hormone known as prolactin, can cause infertility in women and erectile dysfunction in men and can impair vision.

Metabolic syndrome

is a common combination of medical conditions, including increased blood pressure, elevated levels of insulin in the blood, excess body fat around the waist, or abnormal cholesterol levels. This syndrome increases the patient's risk of heart disease, stroke, and type 2 diabetes.

Galactorrhea

is a condition in which an excess of prolactin causes the breasts to produce milk spontaneously, not due to childbirth.

Prediabetes

is a condition in which the blood glucose level is higher than normal, but not high enough to be classified as type 2 diabetes. However, this condition indicates an increased risk of developing type 2 diabetes, heart disease, and stroke.

Cretinism

is a congenital form of hypothyroidism. If treatment is not started soon after birth, cretinism causes arrested physical and mental development.

thyroid-stimulating hormone assay

is a diagnostic test to measure the circulating blood level of thyroid-stimulating hormone. This test is used to detect abnormal thyroid activity resulting from excessive pituitary stimulation.

Graves' disease

is a disorder of unknown cause in which the immune system attacks the thyroid gland and stimulates it to make excessive amounts of thyroid hormone (Figure 13.7). This results in hyperthyroidism and can also cause goiter, exophthalmos, or both. Note: A simple way to remember the difference between Hashimoto's disease (hypothyroidism) and Graves' disease (hyperthyroidism) is that the Hashimoto's has an o in it like in hypo-, and Graves' has an e in it like in hyper-.

Gestational diabetes mellitus

is a form of diabetes mellitus that occurs during some pregnancies. This condition usually disappears after delivery; however, many of these women have an increased risk of developing type 2 diabetes in later life.

laparoscopic adrenalectomy

is a minimally invasive surgical procedure to remove one or both adrenal glands (adrenal means adrenal gland, and -ectomy means surgical removal).

Ketosis

is a normal metabolic process that helps the body utilize stored fat when other sources of energy are lacking. An excessively high level of ketosis may indicate that the body is not producing enough insulin to convert glucose into energy.

endocrinologist

is a physician who specializes in diagnosing and treating diseases and malfunctions of the endocrine glands (endocrin means to secrete within, and -ologist means specialist).

Leptin

is a protein hormone secreted by fat cells that is involved in the regulation of appetite. Leptin leaves the fat cells and travels in the bloodstream to the brain, where it acts on the hypothalamus to suppress appetite and burn fat stored in adipose tissue. In contrast, ghrelin (GREL-in) is a hormone produced in the gastrointestinal tract. Sometimes referred to as the hunger hormone, research is ongoing to flesh out the role that leptin and ghrelin play in rising levels of obesity. Ghrelin is a recent term created from the words "growth hormone rel(easing)" with the suffix -in.

Acromegaly

is a rare chronic disease characterized by abnormal enlargement of the extremities (hands and feet) caused by the excessive secretion of growth hormone after puberty (acr/o means extremities, and -megaly means enlargement). Contrast with gigantism.

pheochromocytoma

is a rare, benign tumor of the adrenal gland that causes too much release of epinephrine and norepinephrine, which are the hormones that regulate heart rate and blood pressure (phe/o means dusky, chrom/o means color, cyt means cell, and -oma means tumor).

Testosterone

is a steroid hormone secreted by the testicles and the adrenal cortex to stimulate the development of male secondary sex characteristics. Estrogen and testosterone are present in both males and females but in dramatically different amounts depending on gender.

human growth hormone

is a synthetic version of the growth hormone that is administered to stimulate growth when the natural supply of growth hormone is insufficient for normal development.

Type 1 diabetes

is an autoimmune insulin deficiency disorder caused by the destruction of pancreatic islet beta cells. Insulin deficiency means that the pancreatic beta cells do not secrete enough insulin. For more information about autoimmune disorders, see Chapter 6. Symptoms of type 1 diabetes include polydipsia, polyphagia, polyuria, weight loss, blurred vision, extreme fatigue, and slow healing. The onset of type 1 diabetes is often triggered by a viral infection. Treatment for type 1 diabetes involves a combination of diet, exercise and carefully regulated insulin replacement therapy administered by injection or insulin pump

Pancreatitis

is an inflammation of the pancreas (pancreat means pancreas, and -itis means inflammation). A leading cause of pancreatitis is long-term alcohol abuse.

Thymitis

is an inflammation of the thymus gland (thym means thymus, and -itis means inflammation).

Type 2 diabetes

is an insulin resistance disorder. Insulin resistance means that insulin is being produced, but the body does not use it effectively. In an attempt to compensate for this lack of response, the body secretes more insulin. With the rise of childhood obesity, type 2 diabetes is increasingly common in children and young adults. Obese adults are also at high risk for this condition.

Gonadotropin

is any hormone that stimulates the gonads (gonad/o means gonad, and -tropin means to stimulate).

Norepinephrine

is both a hormone and a neurohormone. It is released as a hormone by the adrenal medulla and as a neurohormone by the sympathetic nervous system.?It plays an important role in the "fight-or-flight response" by raising blood pressure, strengthening the heartbeat, and stimulating muscle contractions.

Hypoparathyroidism

is caused by an insufficient or absent secretion of the parathyroid hormone (hypo- means deficient, parathyroid means parathyroid, and -ism means condition). This condition causes hypocalcemia, and in severe cases, it leads to tetany. Tetany is the condition of periodic, painful muscle spasms and tremors. Hypoparathyroidism is the opposite of hyperparathyroidism.

Hypercalcemia

is characterized by abnormally high concentrations of calcium circulating in the blood instead of being stored in the bones and teeth (hyper- means excessive, calc means calcium, and -emia means blood condition). This can lead to weakened bones and the formation of kidney stones. Hypercalcemia is the opposite of hypocalcemia.

Hypocalcemia

is characterized by abnormally low levels of calcium in the blood (hypo- means deficient, calc means calcium, and -emia means blood condition). Hypocalcemia is the opposite of hypercalcemia.

Polyphagia

is excessive hunger (poly- means many, and -phagia means eating).

Polydipsia

is excessive thirst (poly- means many, and -dipsia means thirst).

Polyuria

is excessive urination (poly- means many, and -uria means urination).

Adrenalitis

is inflammation of the adrenal glands (adrenal means adrenal glands, and -itis means inflammation).

thymus

is located near the midline in the anterior portion of the thoracic cavity. It is posterior to (behind) the sternum and slightly superior to (above) the heart. The thymus functions as part of the endocrine system by secreting a hormone that functions as part of the immune system, helping develop the body's immune system before birth and in childhood. Its function is greatly reduced after puberty, and it slowly turns into fatty tissue.

oral glucose tolerance test (OGTT)

is most commonly performed to diagnose gestational diabetes. After fasting at least 8 hours, the patient drinks a liquid containing a high concentration of sugar, and the blood glucose level is tested after 1 hour and again after 2 hours.

Glucose

is the basic form of energy used by the body. Glucose in the bloodstream is also known as blood sugar.

Hypogonadism

is the condition of deficient secretion of hormones by the sex glands (hypo- means deficient, gonad means sex gland, and -ism means condition). Compare with hypergonadism.

Gynecomastia

is the condition of excessive mammary development in the male (gynec/o means female, mast means breast, and -ia means abnormal condition). This is caused by a decrease in testosterone.

Hypergonadism

is the condition of excessive secretion of hormones by the sex glands (hyper- means excessive, gonad means sex gland, and -ism means condition). Compare with hypogonadism.

Hyperinsulinism

is the condition of excessive secretion of insulin in the bloodstream (hyper- means excessive, insulin means insulin, and -ism means condition). Hyperinsulinism can cause hypoglycemia.

Hyperpituitarism

is the excess secretion of growth hormone that causes acromegaly and gigantism (hyper- means excessive, pituitar means pituitary, and -ism means condition). Short stature, formerly known as dwarfism, is sometimes caused by deficient secretion of growth hormone

Progesterone

is the hormone released during the second half of the menstrual cycle by the corpus luteum in the ovary. Its function is to complete the preparation of the uterus for possible pregnancy

Insulin

is the hormone secreted by the beta cells of the pancreatic islets in response to high levels of glucose in the bloodstream. Insulin functions in two ways: When energy is needed, insulin allows glucose to enter the cells to be used as this energy. When additional glucose is not needed, insulin stimulates the liver to convert glucose into glycogen for storage.

Thyroid carcinoma

is the most common cancer of the endocrine system, and is the most rapidly increasing cancer in the United States. Thyroid carcinoma, which has a high survival rate, affects significantly more women than men and is commonly diagnosed between ages 20 and 55.

Thymosin

which plays an important part in the immune system by stimulating the maturation of lymphocytes into T cells

Endocrine glands

which produce hormones, do not have ducts (endo- means within, and -crine means to secrete).

Puberty

is the process of physical changes by which a child's body becomes an adult body that is capable of reproducing (Figure 13.6). It is marked by maturing of the genital organs, the development of secondary sex characteristics, and the first occurrence of menstruation in the female. In the United States the average age is 12 for girls and 11 for boys. Precocious puberty is the early onset of the changes of puberty, usually before age 8 in girls and age 9 in boys. Precocious means exceptionally early in development or occurrence.

hypophysectomy

is the removal of abnormal glandular tissue (hypophys refers to the pituitary gland, and -ectomy means removal). This surgery is performed through the nasal passages.

pancreatectomy

is the surgical removal of all or part of the pancreas (pancreat means pancreas, and -ectomy means surgical removal). A total pancreatectomy is performed to treat pancreatic cancer. This procedure also involves removing the spleen, gallbladder, common bile duct, and portions of the small intestine and stomach.

thymectomy

is the surgical removal of the thymus gland (thym means thymus, and -ectomy means surgical removal).

thyroid gland

lies on either side of the larynx, just below the thyroid cartilage. One of the primary functions of the thyroid gland is to regulate the body's metabolism. The term metabolism describes all of the processes involved in the body's use of nutrients, including the rate at which they are used. Thyroid secretions also influence growth and the functioning of the nervous system. The two primary thyroid hormones regulate the rate of metabolism and affect the growth and rate of function of many other body systems. They are: -thyroxine (T4) -triiodothyronine (T3) The rate of secretion of these two hormones is controlled by the thyroid-stimulating hormone produced by the anterior lobe of the pituitary gland.

fructosamine test

measures average glucose levels over the previous 3 weeks. The fructosamine test is able to detect changes more rapidly than the HbAlc test.

Home blood glucose monitoring

measures the current blood glucose level using a drop of blood, and is often performed by the patient multiple times per day.

Heart disease

occurs because excess blood glucose makes the walls of the blood vessels sticky and rigid. This encourages hypertension and atherosclerosis

Diabetic retinopathy

occurs when diabetes damages the tiny blood vessels in the retina. This causes blood to leak into the posterior segment of the eyeball and produces the damage that causes the loss of vision

pituitary gland

or hypophysis, is a pea-sized gland that is divided into two parts, the anterior and the posterior lobes. These lobes hang from a stalk-like structure located below the hypothalamus in the brain (Figure 13.2). The hypothalamus is part of the nervous system that produces hormones that control many body functions (see Chapter 10).

Addison's disease

sometimes referred to as Addison disease, occurs when the adrenal glands do not produce enough of the hormones cortisol or aldosterone. This potentially life-threatening condition is characterized by chronic, worsening fatigue and muscle weakness; loss of appetite; low blood pressure; and weight loss. Many patients also develop patches of dark skin.

random blood glucose test

uses a blood drop sample to measure the current blood glucose level without fasting and can be used to diagnose diabetes.

adrenal glands

which are also known as the suprarenals, are so named because they are located on top of each kidney. Each of these glands consists of an outer portion, known as the adrenal cortex, and the middle portion, which is the adrenal medulla. Each of these parts has a specialized role

Myxedema

which is also known as adult hypothyroidism, is caused by an extreme deficiency of thyroid secretion. Symptoms include swelling, particularly around the eyes and cheeks; fatigue; and a subnormal temperature.

Calcitonin

which is produced by the thyroid gland, is a hormone that works with the parathyroid hormone to decrease calcium levels in the blood and tissues by moving calcium into storage in the bones and teeth.

Hyperparathyroidism

which is the overproduction of the parathyroid hormone, causes the condition known as hypercalcemia (hyper- means excessive, parathyroid means parathyroid, and -ism means condition). Hyperparathyroidism can result from a disorder of the parathyroid gland or from a disorder elsewhere in the body, such as kidney failure. Hyperparathyroidism is the opposite of hypoparathyroidism.

parathyroidectomy

which is the surgical removal of one or more of the parathyroid glands, is performed to control hyperparathyroidism (parathyroid means parathyroid glands and -ectomy means surgical removal).

thyroid scan

which measures thyroid function, is a form of nuclear medicine