Gale Encyclopedia of Medicine Vol 3 (G M) pdf
GALE The
ENCYCLOPEDIA
M EDICINE ofThe GALE
ENCYCLOPEDIA
ofM EDICINE
SECOND EDITION
J A C Q U E L I N E L . L O N G E , E D I T O R
D E I R D R E S . B L A N C H F I E L D , A S S O C I A T E E D I T O R
V O L U M E
G-M
3
STAFF Jacqueline L. Longe, Project Editor Deirdre S. Blanchfield, Associate Editor Christine B. Jeryan, Managing Editor Donna Olendorf, Senior Editor Stacey Blachford, Associate Editor Kate Kretschmann, Melissa C. McDade, Ryan
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II. Blanchfield, Deirdre S. III. Gale Research Company. RC41.G35 2001 616’.003—dc21
1. Internal medicine—Encyclopedias. I. Longe, Jacqueline L.
ISBN 0-7876-5489-2 (set: hardcover) — ISBN 0-7876-5490-6 (vol. 1) — ISBN 0-7876-5491-4 (vol. 2) — ISBN 0-7876-5492-2 (vol. 3) — ISBN 0-7876-5493-0 (vol. 4) — ISBN 0-7876-5494-9 (vol. 5)
Library of Congress Cataloging-in-Publication Data Gale encyclopedia of medicine / Jacqueline L. Longe, editor; Deirdre S. Blanchfield, associate editor — 2nd ed. p. cm. Includes bibliographical references and index. Contents: Vol. 1. A-B — v. 2. C-F — v. 3. G-M — v. 4. N-S — v. 5. T-Z.
ISBN 0-7876-5489-2 (set) 0-7876-5490-6 (Vol. 1) 0-7876-5491-4 (Vol. 2) 0-7876-5492-2 (Vol. 3) 0-7876-5493-0 (Vol. 4) 0-7876-5494-9 (Vol. 5) Printed in the United States of America 10 9 8 7 6 5 4 3 2 1
ENCYCLOPEDIA of MEDICINE
SECOND EDITION
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Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Advisory Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Entries
Volume 1: A-B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 Volume 2: C-F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625
Volume 3: G-M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1375
Volume 4: N-S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2307
Volume 5: T-Z . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3237
Organizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3603
General Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3625
CONTENTS The Gale Encyclopedia of Medicine 2 is a medical ref- erence product designed to inform and educate readers about a wide variety of disorders, conditions, treatments, and diagnostic tests. The Gale Group believes the product to be comprehensive, but not necessarily definitive. It is intended to supplement, not replace, consultation with a physician or other healthcare practitioner. While the Gale Group has made substantial efforts to provide information that is accurate, comprehensive, and up-to-date, the Gale Group makes no representations or warranties of any kind, including without limitation, warranties of mer- chantability or fitness for a particular purpose, nor does it guarantee the accuracy, comprehensiveness, or timeliness of the information contained in this product. Readers should be aware that the universe of medical knowledge is constantly growing and changing, and that differences of medical opinion exist among authorities. Readers are also advised to seek professional diagnosis and treatment for any medical condition, and to discuss information obtained from this book with their health care provider.
PLEASE READ—IMPORTANT INFORMATION
INTRODUCTION
Definition Definition Description Purpose Causes and symptoms Precautions Diagnosis Description Treatment Preparation Alternative treatment Aftercare Prognosis Risks Prevention Normal/Abnormal results Resources Resources Key terms Key terms
print hyperlinks that point the reader to related entries in the encyclopedia.
The Gale Encyclopedia of Medicine 2 has been designed with ready reference in mind.
The essays were compiled by experienced medical writers, including physicians, pharmacists, nurses, and other health care professionals. GEM2 medical advisors reviewed the completed essays to insure that they are appropriate, up-to-date, and medically accurate.
A preliminary list of diseases, disorders, tests and treat- ments was compiled from a wide variety of sources, including professional medical guides and textbooks as well as consumer guides and encyclopedias. The general advisory board, made up of public librarians, medical librarians and consumer health experts, evaluated the top- ics and made suggestions for inclusion. The list was sorted by category and sent to GEM2 medical advisors, certified physicians with various medical specialities, for review. Final selection of topics to include was made by the med- ical advisors in conjunction with the Gale Group editor.
Alternative treatment sections for diseases and condi- tions that may be helped by complementary therapies.
In recent years there has been a resurgence of interest in holistic medicine that emphasizes the connection between mind and body. Aimed at achieving and main- taining good health rather than just eliminating disease, this approach has come to be known as alternative medi- cine. The Gale Encyclopedia of Medicine 2 includes a number of essays on alternative therapies, ranging from traditional Chinese medicine to homeopathy and from meditation to aromatherapy. In addition to full essays on alternative therapies, the encyclopedia features specific
Disorders/Conditions Tests/Treatments
The Gale Encyclopedia of Medicine 2 (GEM2) is a one-stop source for medical information on nearly 1,700 common medical disorders, conditions, tests, and treat- ments, including high-profile diseases such as AIDS, Alzheimer’s disease, cancer, and heart attack. This ency- clopedia avoids medical jargon and uses language that laypersons can understand, while still providing thor- ough coverage of each topic. The Gale Encyclopedia of
Many common drugs are also covered, with generic drug names appearing first and brand names following in parentheses, eg. acetaminophen (Tylenol). Throughout the Gale Encyclopedia of Medicine 2, many prominent individuals are highlighted as sidebar biographies that accompany the main topical essays. Articles follow a standardized format that provides information at a glance. Rubrics include:
Gale Encyclopedia of Medicine 2 , including disorders/ conditions, tests/procedures, and treatments/therapies.
Almost 1,700 full-length articles are included in the
SCOPE
fills a gap between basic consumer health resources, such as single-volume family medical guides, and highly technical professional materials.
Medicine 2
- Straight alphabetical arrangement allows users to locate information quickly.
- Bold-faced terms function as
Cross-references placed throughout the encyclopedia Resources section directs users to additional sources
- direct readers to where information on subjects with- of medical information on a topic. out entries can be found. Synonyms are also cross-ref-
- A comprehensive general index allows users to easily
oduction erenced.
target detailed aspects of any topic, including Latin
Intr names.
- A list of key terms are provided where appropriate to define unfamiliar terms or concepts.
GRAPHICS
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Director
Contributors Galactorrhea is the secretion of breast milk in men, or in women who are not breastfeeding an infant.
Lactation, or the production of breast milk, is a nor- mal condition occurring in women after delivery of a baby. Many women who have had children may even be able to express a small amount of breast milk from the nipple up to two years after childbirth. Galactorrhea, or hyperlactation, however, is a rare condition that can occur in both men and women, where a white or grayish fluid is secreted by the nipples of both breasts. While this condition is not serious in itself, galactorrhea can indi- cate more serious conditions, including hormone imbal- ances or the presence of tumors.
Causes Galactorrhea is associated with a number of condi- tions. The normal production of breast milk is controlled by a hormone called prolactin, which is secreted by the pituitary gland in the brain. Any condition that upsets the balance of hormones in the blood or the production of hormones by the pituitary gland or sexual organs can stimulate the production of prolactin.
Often, a patient with galactorrhea will have a high level of prolactin in the blood. A tumor in the pituitary gland can cause this overproduction of prolactin. At least 30% of women with galactorrhea, menstrual abnormali- ties, and high prolactin levels have a pituitary gland tumor. Other types of brain tumors, head injuries, or encephalitis (an infection of the brain) can also cause galactorrhea.
Tumors or growths in the ovaries or other reproduc- tive organs in women, or in the testicles or related sexual organs of men, can also stimulate the production of pro- lactin. Any discharge of fluid from the breast after a woman has passed menopause may indicate breast can- cer. However, most often the discharge associated with breast cancer will be from one breast only. In galactor- rhea both breasts are usually involved. The presence of blood in the fluid discharged from the breast could indi- cate a benign growth in the breast tissue itself. In approx- imately 10–15% of patients with blood in the fluid, carci- noma of the breast tissue is present.
A number of medications and drugs can also cause galactorrhea as a side-effect. Hormonal therapies (like oral contraceptives), drugs for treatment of depression or other psychiatric conditions, tranquilizers, morphine, heroin, and some medications for high blood pressure can cause galactorrhea.
Several normal physiologic situations can cause pro- duction of breast milk. Nipple stimulation in men or women during sexual intercourse may induce lactation, for women particularly during or just after pregnancy.
Even after extensive testing, no specific cause can be determined for some patients with galactorrhea.
Symptoms The primary symptom of galactorrhea is the dis- charge of milky fluid from both breasts. In women, galactorrhea may be associated with infertility, menstru- al cycle irregularities, hot flushes, or amenorrhea—a condition where menstruation stops completely. Men may experience loss of sexual interest and impotence.
Headaches and visual disturbances have also been asso- ciated with some cases of galactorrhea.
Galactorrhea is generally considered a symptom that may indicate a more serious problem. Collection of a thorough medical history, including pregnancies, surg- eries, and consumption of drugs and medications is a
G
Galactorrhea Definition
Description
Causes and symptoms
Diagnosis
Prognosis
K E Y T E R M S
Prevention
first step in diagnosing the cause of galactorrhea. A
physical examination, along with a breast examination,
Galactosemia
Galactosemia is an inborn error of metabolism. “Metabolism” refers to all chemical reactions that take
Galactosemia is a rare but potentially life-threaten- ing disease that results from the inability to metabolize galactose. Serious consequences from galactosemia can be prevented by screening newborns at birth with a sim- ple blood test.
Galactosemia is an inherited disease in which the transformation of galactose to glucose is blocked, allow- ing galactose to increase to toxic levels in the body. If galactosemia is untreated, high levels of galactose cause vomiting, diarrhea, lethargy, low blood sugar, brain damage, jaundice, liver enlargement, cataracts, suscep- tibility to infection, and death.
Altha Roberts Edgren
16th ed. Ed. Robert Berkow. Rahway, NJ: Merck Research Laboratories, 1992.
5th ed. Springhouse, PA: Springhouse Corpora- tion, 1995. “Galactorrhea.” In The Merck Manual of Diagnosis and Thera- py.
37th ed. Stamford: Appleton & Lange, 1997. “Galactorrhea (Hyperprolactinemia).” In Professional Guide to Diseases.
Philadelphia: W. B. Saunders Co., 1996. “Galactorrhea.” In Current Medical Diagnosis & Treatment, 1998.
Resources BOOKS Bennett, J. Claude, and Fred Plum, eds. Cecil Textbook of Med- icine.
There is no way to prevent galactorrhea. If the con- dition is caused by the use of a particular drug, a patient may be able to switch to a different drug that does not have the side-effect of galactorrhea.
Treatment with bromocriptine is usually effective in stopping milk secretion, however, symptoms may recur if drug therapy is discontinued. Surgical removal or radia- tion treatment may correct the problem permanently if it is related to a tumor. Frequent monitoring of hormone status and tumor size may be recommended.
Hyperlactation—Another term for galactorrhea. Lactation—The production of breast milk.
Bromocriptine—Also known as Parlodel, the main drug used to treat galactorrhea by reducing levels of the hormone prolactin.
Amenorrhea —Abnormal cessation of menstrua- tion.
Treatment
Galactorrhea is more of a nuisance than a real threat to health. While it is important to find the cause of the condition, even if a tumor is discovered in the pituitary gland, it may not require treatment. With very small, slow-growing tumors, some physicians may suggest a “wait and see” approach.
Treatment for galactorrhea will depend on the cause of the condition and the symptoms. The drug bromocrip- tine is often prescribed first to reduce the secretion of prolactin and to decrease the size of pituitary tumors. This drug will control galactorrhea symptoms and in many cases may be the only therapy necessary. Oral estrogen and progestins (hormone pills, like birth control pills) may control symptoms of galactorrhea for some women. Surgery to remove a tumor may be required for patients who have more serious symptoms of headache and vision loss, or if the tumor shows signs of enlarge- ment despite drug treatment. Radiation therapy has also been used to reduce tumor size when surgery is not pos- sible or not totally successful. A combination of drug, surgery, and radiation treatment can also be used.
ic resonance imaging (MRI) scan to locate tumors or abnormalities in tissues.
A mammogram (an x ray of the breast) or an ultra- sound scan (using high frequency sound waves) might be used to determine if there are any tumors or cysts present in the breasts themselves. If a tumor of the pituitary gland is suspected, a series of computer assisted x rays called a computed tomography scan (CT scan) may be done. Another procedure that may be useful is a magnet-
will usually be conducted. Blood and urine samples may be taken to determine levels of various hormones in the body, including prolactin and compounds related to thy- roid function.
Galactosemia Definition
Description
place in living organisms. A metabolic pathway is a series of reactions where the product of each step in the series is the starting material for the next step. Enzymes are the chemicals that help the reactions occur. Their ability to function depends on their structure, and their structure is determined by the deoxyribonucleic acid (DNA) sequence of the genes that encode them. Inborn errors of metabolism are caused by mutations in these genes which do not allow the enzymes to function properly.
Galactosemia
Causes and symptoms
Every cell in a person’s body has two copies of each gene. Each of the forms of galactosemia is inherit- ed as a recessive trait, which means that galactosemia is only present in individuals with two mutated copies of one of the three genes. This also means that carriers, with only one copy of a gene mutation, will not be aware that they are carrying a mutation (unless they have had a genetic test), as it is masked by the normal gene they also carry and they have no symptoms of the disease. For each step in the conversion of galactose to glucose, if only one of the two copies of the gene con- trolling that step is normal (i.e. for carriers), enough functional enzyme is made so that the pathway is not blocked at that step. If a person has galactosemia, both copies of the gene coding for one of the enzymes required to convert glucose to galactose are defective and the pathway becomes blocked. If two carriers of the same defective gene have children, the chance of any of their children getting galactosemia (the chance of a child getting two copies of the defective gene) is 25% (one in four) for each pregnancy.
Classic galactosemia occurs in the United States about one in every 50,000–70,000 live births.
Galactosemia I
Galactosemia I (also called classic galactosemia), the first form to be discovered, is caused by defects in both copies of the gene that codes for an enzyme called galactose-1-phosphate uridyl transferase (GALT). There are 30 known different mutations in this gene that cause GALT to malfunction.
Newborns with galactosemia I appear normal at birth, but begin to develop symptoms after they are given milk for the first time. Symptoms include vomiting, diar- rhea, lethargy (sluggishness or fatigue), low blood glu- cose, jaundice (a yellowing of the skin and eyes), enlarged liver, protein and amino acids in the urine, and susceptibility to infection, especially from gram negative bacteria. Cataracts (a grayish white film on the eye lens) can appear within a few days after birth. People with galactosemia frequently have symptoms as they grow older even though they have been given a galactose-free diet. These symptoms include speech disorders, cataracts, ovarian atrophy and infertility in females, learning disabilities, and behavioral problems.