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Alternative Names: Hypercortisolism.
Cushing's syndrome is a hormonal disorder caused by prolonged exposure of the body's tissues to high levels of the hormone cortisol.
Normally, the production of cortisol follows a precise chain of events. First, the hypothalamus, a part of the brain which is about the size of a small sugar cube, sends corticotropin releasing hormone (CRH) to the pituitary gland. CRH causes the pituitary to secrete ACTH (adrenocorticotropin), a hormone that stimulates the adrenal glands. When the adrenals receive the ACTH, they respond by releasing cortisol into the bloodstream.
When the amount of cortisol in the blood is adequate, the hypothalamus and pituitary release less CRH and ACTH. This ensures that the amount of cortisol released by the adrenal glands is precisely balanced to meet the body's daily needs. However, if something goes wrong with the adrenals or their regulating mechanisms in the pituitary gland or the hypothalamus, cortisol production can become abnormal.
Some patients may have sustained high cortisol levels without the effects of Cushing's syndrome. These high cortisol levels may be compensating for the body's resistance to cortisol's effects. This rare syndrome of cortisol resistance is a genetic condition that causes hypertension and chronic androgen excess.
Incidence; Causes & Development
Cushing's syndrome is relatively rare and most commonly affects adults aged 20 to 50.
The most common cause of Cushing's is a tumor in the pituitary gland, and the least common is cancer of the adrenal gland. Many people suffer the symptoms of Cushing's syndrome because they take glucocorticoid hormones - such as prednisone - as an antiinflammatory. Some develop Cushing's syndrome because of overproduction of cortisol by the body.
Other causes include:- Ectopic ACTH Syndrome: Some benign or malignant tumors that arise outside the pituitary can produce ACTH. This condition is known as ectopic ACTH syndrome. Lung tumors cause over 50% of these cases and men are affected 3 times more frequently than women. The most common forms of ACTH-producing tumors are oat cell, or small cell lung cancer, which accounts for about 25% of all lung cancer cases, and carcinoid tumors. Other less common types of tumors that can produce ACTH are thymomas, pancreatic islet cell tumors, and medullary carcinomas of the thyroid.
- Adrenal Tumors: Sometimes, an abnormality of the adrenal glands, most often an adrenal tumor, causes Cushing's syndrome. The average age of onset is about 40 years. Most of these cases involve non-cancerous tumors of adrenal tissue, called adrenal adenomas, which release excess cortisol into the blood.
- Familial Cushing's Syndrome: Most cases of Cushing's syndrome are not inherited. Rarely, however, some individuals have special causes of Cushing's syndrome due to an inherited tendency to develop tumors of one or more endocrine glands. In Primary Pigmented Micronodular Adrenal Disease, children or young adults develop small cortisol-producing tumors of the adrenal glands. In Multiple Endocrine Neoplasia Type I (MEN I), hormone secreting tumors of the parathyroid glands, pancreas and pituitary occur. Cushing's syndrome in men may be due to pituitary, ectopic or adrenal tumors.
Diagnosis & Tests
Diagnosis is based on a review of the patient's medical history, physical examination and laboratory tests. Often X-ray exams of the adrenal or pituitary glands are useful for locating tumors. These tests help to determine if excess levels of cortisol are present and why.
Sometimes other conditions may be associated with many of the symptoms of Cushing's syndrome. These include polycystic ovarian syndrome, which may cause menstrual disturbances, weight gain from adolescence, excess hair growth and sometimes impaired insulin action and diabetes. Commonly, weight gain, high blood pressure and abnormal levels of cholesterol and triglycerides in the blood are associated with resistance to insulin action and diabetes; this has been described as the "Metabolic Syndrome-X." Patients with these disorders do not have abnormally elevated cortisol levels.
Treatment & Prevention
Treatment depends on the specific reason for cortisol excess and may include surgery, radiation, chemotherapy or the use of cortisol-inhibiting drugs. If the cause is long-term use of glucocorticoid hormones to treat another disorder, the doctor will gradually reduce the dosage to the lowest dose adequate for control of that disorder. Once control is established, the daily dose of glucocorticoid hormones may be doubled and given on alternate days to lessen side-effects.
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Recommendations and treatments for Cushing's Syndrome / Hypercortisolism: | | | | | Lab Tests/Rule-Outs |  Test Adrenal Function | A 24-Hour urinary free cortisol level is the most specific diagnostic test. Levels higher than 50 to 100mcg per day for an adult suggest Cushing's syndrome. Once Cushing's syndrome has been diagnosed, other tests are used to find the exact location of the abnormality that leads to excess cortisol production. These tests could include dexamethasone suppression test, CRH stimulation test, direct visualization of the endocrine glands (radiologic imaging), petrosal sinus sampling and the dexamethasone-CRH test. |
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KEY | | Highly recommended |
GLOSSARY
Adrenal (Adrenal Gland, Adrenal Glands, Adrenals)
The adrenal glands sit on top of each kidney and consist of an outer cortex and an inner medulla. Of the 50 or so hormones the adrenals make, only cortisone and adrenaline are recognized by most people. Some of these hormones must be produced to preserve life, while others help resist stress. Other hormones from the adrenals control normal energy output (along with the thyroid) and govern the breakdown of stored energy into quick energy sources. The medulla produces epinephrine and norepinephrine, which are specifically designed to help the body deal with stressful situations. The adrenals control the body's potassium/sodium balance, which is vital for energy production. They also produce sex hormones in minute amounts, which is important for later years when the gonads drop or cease their production.
Androgen
Any steroid hormone that increases male characteristics.
Anti-inflammatory (Antiinflammatory)
Reducing inflammation by acting on body mechanisms, without directly acting on the cause of inflammation, e.g., glucocorticoids, aspirin.
Benign
Literally: innocent; not malignant. Often used to refer to cells that are not cancerous; they tend to grow slowly and don't spread (metastasize) like cancer tumors do.
Cancer
Refers to the various types of malignant neoplasms that contain cells growing out of control and invading adjacent tissues, which may metastasize to distant tissues.
Chemotherapy
A treatment of disease by any chemicals. Used most often to refer to the chemical treatments used to combat cancer cells. Chemotherapy is usually given in cycles: a treatment period followed by a recovery period, then another treatment period, and so on. Most anticancer drugs are given by injection into a blood vessel (IV); some are given by mouth. Chemotherapy is a systemic therapy, meaning that the drugs enter the bloodstream and travel throughout the body. Usually, a patient has chemotherapy as an outpatient (at the hospital, at the doctor's office, or at home). However, depending on which drugs are given and the patient's general health, a short hospital stay may be needed.
Cholesterol
A waxy, fat-like substance manufactured in the liver and found in all tissues, it facilitates the transport and absorption of fatty acids. In foods, only animal products contain cholesterol. An excess of cholesterol in the bloodstream can contribute to the development of atherosclerosis.
Chronic (Chronicity)
Usually referring to chronic illness: Illness extending over a long period of time.
Cortisol
A hormone. Its most important function is to help the body respond to stress. It also helps regulate your body's use of protein, carbohydrates and fat; it helps maintain blood pressure and cardiovascular function; it stems inflammation.
Diabetes Mellitus (Diabetes, Diabetic, Diabetics)
A disease with increased blood glucose levels due to lack or ineffectiveness of insulin. Diabetes is found in two forms; insulin-dependent diabetes (juvenile-onset) and non-insulin-dependent (adult-onset). Symptoms include increased thirst; increased urination; weight loss in spite of increased appetite; fatigue; nausea; vomiting; frequent infections including bladder, vaginal, and skin; blurred vision; impotence in men; bad breath; cessation of menses; diminished skin fullness. Other symptoms include bleeding gums; ear noise/buzzing; diarrhea; depression; confusion.
Ectopic
Located outside normal position, e.g., location of fetus in pregnancy.
Endocrine Glands
A set of glands including the pituitary, hypothalamus, pineal, thyroid, parathyroid, thymus and adrenal glands, as well as the pancreas, ovaries and testes.
Gland (Glands)
The glandular system is one of the most important and complicated systems of the body. Gland tissue can be either an organ or general tissue that secretes chemicals and there are two types of gland: exocrine and endocrine. Those glands which secrete chemicals through tubules or ducts are called exocrine and include sweat, tear and salivary glands. Ductless glands - part of the endocrine system - secrete special chemicals (hormones) directly into the blood.
Glucocorticoid
Any steroid-like compound capable of significantly influencing intermediary metabolism, such as promotion of deposition of glycogen in the liver, and of exerting a useful antiinflammatory effect.
Hormones (Hormone)
Chemical substances secreted by a variety of body organs that are carried by the bloodstream and usually influence cells some distance from the source of production. Hormones signal certain enzymes to perform their functions and, in this way, regulate such body functions as blood sugar levels, insulin levels, the menstrual cycle, and growth. These can be prescription, over-the-counter, synthetic or natural agents. Examples include adrenal hormones such as corticosteroids and aldosterone; glucagon, growth hormone, insulin, testosterone, estrogens, progestins, progesterone, DHEA, melatonin, and thyroid hormones such as thyroxine and calcitonin.
Hypertension
High blood pressure. Hypertension increases the risk of heart attack, stroke, and kidney failure because it adds to the workload of the heart, causing it to enlarge and, over time, to weaken; in addition, it may damage the walls of the arteries.
Hypothalamus (Hypothalmus)
Tucked deep inside the brain, this gland is an important supervisory center, regulating many body functions. It is important for longevity and coordinates the entire endocrine system, especially in connection with the pituitary. The hypothalamus is located immediately below the thalamus at the center of the brain, and controls many automatic functions of the body. This means it has the power to govern the autonomic (automatic or subconscious) nervous system. The hypothalamus also controls pituitary output by secreting specific chemicals to the pituitary's front lobe. Despite its importance in maintaining homeostasis, the hypothalamus in humans accounts for only 1/300 of total brain weight, and is about the size of an almond.
Insulin
A hormone secreted by the pancreas in response to elevated blood glucose levels. Insulin stimulates the liver, muscles, and fat cells to remove glucose from the blood for use or storage.
Lung (Lungs, Pulmonary)
Organ of the body, located in the chest cavity which is designed to bring oxygen from the air into the blood stream, while also expelling carbon dioxide and other waste gases out of the body. Pulmonary: Related to the lungs.
Malignant (Cancerous)
Dangerous. Mainly used to describe a cancerous growth -- when used this way, it means the growth is cancerous and predisposed to spreading.
Menstruation (Menses, Menstrual, Menstrual Cycle, Menstrual Cycles, Menstrual Flow, Menstrual Phase, Monthly Cycle)
The periodic discharge of blood, tissue fluid and mucus from the endometrium (lining of the uterus) that usually lasts from 3 - 5 days. It is caused by a sudden reduction in estrogens and progesterone.
Metabolism (Metabolic, Metabolize, Metabolizes, Metabolizing)
The chemical processes of living cells in which energy is produced in order to replace and repair tissues and maintain a healthy body. Responsible for the production of energy, biosynthesis of important substances, and degradation of various compounds. Also defined as the sum total of changes in an organism in order to achieve a balance (homeostasis): Catabolic burns up, anabolic stores and builds up; the sum of their work is metabolism.
Microgram (mcg, Micrograms, ug)
0.000001 or a millionth of a gram.
Neoplasia
The presence of abnormal cells forming a growth or tumor, unable to perform their normal functions, and replacing healthy cells.
Pancreas (Pancreatic)
Opposite the liver and behind the stomach, the pancreas has two main functions - to manufacture various enzymes for digestion, and to release hormones to help control the body's use of carbohydrates. It releases insulin to help each cell absorb glucose to burn as energy. In this way, insulin controls the amount of sugar (glucose) in the blood. Proper pancreatic function is very important: too much, too little, or no insulin production can be life-threatening. Some of the chemicals released by the pancreas are not hormones, but stimulate other glands to make hormones. Once again, balance is necessary. Nutritional requirements for the pancreas are many. Research indicates that chromium vitamins C, E, B-complex, calcium, magnesium and potassium are especially important.
Parathyroid (Parathyroid Gland, Parathyroid Glands, Parathyroids)
The four parathyroid glands are embedded near the thyroid, with two attached to each thyroid lobe, on opposites sides of the throat. Hormones from the parathyroid glands help control calcium and phosphorous levels in the body. These glands oversee the breaking down of bone cells to release more of these minerals into the blood; a hormone from the thyroid has the opposite effect, and builds up the bones. Control of this system depends on blood levels of calcium ions: low levels "turn on" hormone production to break down bone tissue, so that blood levels remain stable. It is important to absorb enough dietary calcium to avoid this breakdown of bone tissue.
Pituitary (Pituitary Gland)
The pituitary gland is a small (half-inch), bean-shaped organ that hangs down from the lower center of the brain on a stalk attached to another gland, the hypothalamus. Weighing less than one gram, the pituitary gland is often called the "master gland" since it controls the secretion of hormones by other endocrine glands. It regulates many body activities, and is partitioned into front and back lobes. The front lobe is stimulated by the hypothalamus, and produces any one of six different hormones that in turn stimulate the thyroid, adrenal and reproductive glands, and also breast milk production.
Sinuses (Sinus)
Four pairs of air pockets lined with membranes in the bones around the nose. The ethmoid sinuses are located on each side of the nose between the eyes; the maxillary sinuses are located in the cheek above the teeth and below the eyes; the sphenoid sinuses are located deeply behind the eyes; the frontal sinuses are located in the forehead.
Syndrome
A medical condition characterized by a collection of related symptoms (what the patient feels) and signs (what a doctor can observe or measure).
Thyroid (Thyroid Gland)
The thyroid gland is an organ with many veins, anchored around the front of the throat near the voice box. It is essential to normal body growth in infancy and childhood. It absorbs iodine from the diet and releases thyroid hormones - iodine-containing compounds that help govern the rate of the body's metabolism (its total life processes), affecting body temperature, and regulating protein, fat and carbohydrate catabolism in all cells. They keep up growth hormone release, skeletal maturation, and heart rate, force, and output. They promote central nervous system growth, stimulate the making of many enzymes, and are necessary for muscle tone and vigor. To a high degree, metabolism is regulated by the hormone thyroxine, which can be made by the thyroid if enough organic iodine is available. An enlarged thyroid gland that is not cancer is sometimes called goitre.
Triglyceride (Triglycerides)
The main form of fat found in foods and the human body. Containing three fatty acids and one unit of glycerol, triglycerides are stored in adipose cells in the body, which, when broken down, release fatty acids into the blood. Triglycerides are fat storage molecules and are the major lipid component of the diet.
X-rays (X-ray)
High-energy radiation used to take pictures of areas inside the body.
Last updated: Jun 15, 2008
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