Archive for June, 2008
Written by dedy on 28 June 2008
Definition
An emotional disorder characterized by severe and potentially life-threatening weight loss through self-induced reduction in total food intake. More than 90% of reported cases occur in women in industrialized countries where thin bodies are considered attractive, though anorexia now occurs in a growing number of men. Although seldom appearing prior to puberty, associated mental disturbances are usually more severe when it does. Mean onset is 17 years; it rarely begins after age 40; onset is often associated with a stressful event; prevalence is 0.5% to 1.0% when full diagnostic criteria are met—higher for subthreshold diagnosis (Eating Disorders Not Otherwise Specified). Death may result—usually caused by starvation, suicide, heart failure, or electrolyte imbalance.
Two subtypes:
Full diagnostic criteria:
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Refusal to maintain minimum body weight for age and height
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Unrealistic fear of weight gain
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Distorted perception of personal body shape and/or size; denial of seriousness of low body weight
- Amenorrhea Read the rest of this entry »
Tags: Anorexia Nervosa
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Written by dedy on 28 June 2008
Definition
Angioedema is a well-circumscribed, nonpitting swelling of the subcutaneous tissues of the skin and mucosa, which is typically nonpruritic. Sites of involvement include eyelids, lips, tongue, larynx, palms, soles, genitalia, and gastrointestinal tract. The condition results from the activity of inflammatory mediators that cause dilation and enhanced permeability of venules and capillaries. Sources of these inflammatory mediators include:
The latter is typically associated with urticaria and pruritis. Angioedema may be distinguished clinically from other types of edema (e.g., congestive heart failure, hypoalbuminemia) by the rapidity of onset (minutes to hours) and by a distribution that is asymmetric and not localized to dependent areas of the body.
Both acquired and inherited forms of the illness exist. Acquired angioedema (AAE) may be acute or chronic (longer than 6 weeks in duration) whereas hereditary angioedema (HAE) is typically chronic and recurrent. Acute AAE is reported to occur in approximately 10% to 20% of the population, while HAE is reported to occur in approximately 0.01% of the population. However, the frequency of angioedema is likely higher than reported because of the self-limited nature of most attacks. Read the rest of this entry »
Tags: Angioedema
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Written by dedy on 28 June 2008
Definition
Angina pectoris, or angina, is chest pain caused by underlying coronary heart disease resulting in myocardial ischemia. Different types include the following.
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Stable angina (“classic”) occurs with exercise, emotional stress, or extreme temperatures. It seldom is associated with permanent damage to the heart muscle.
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Unstable angina occurs even at rest. Patients may present with symptoms resembling a myocardial infarction but with no evidence of heart muscle damage. Unstable angina may progress to acute myocardial infarction and should be treated as an emergency.
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Prinzmetal’s or variant angina is a rare condition that occurs at rest and is caused by coronary artery spasm with electrocardiographic changes. This type of angina should be treated as a medical emergency, because it is often associated with acute myocardial infarction, ventricular tachycardia and fibrillation, and sudden cardiac death.
- Microvascular angina is chest pain in patients with no apparent coronary artery blockages and is caused by poor functioning of smaller blood vessels. Read the rest of this entry »
Tags: Angina, Angina pectoris
Posted in Medical | 2 Comments »
Written by dedy on 28 June 2008
Definition
Anemia is characterized by a reduction in either the hematocrit (red blood cell [RBC] volume <42% in men and <36% in women) or the concentration of hemoglobin (<14 g/dL in men and <12 g/dL in women). The prevalence of anemia is highest among menstruating women (5.8%), infants (5.7%), and the elderly (12%). Anemias can be distinguished morphologically based on the size of the RBCs or the mean corpuscular volume.
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Microcytic anemias are characterized by small RBCs (mean corpuscular volume <80 fL) and include iron-deficiency anemia, anemia of chronic disease, thalassemias, and sideroblastic anemias.
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Macrocytic anemias are characterized by large RBCs (mean corpuscular volume >98 fL) and include megaloblastic anemias (e.g., from vitamin B12 [pernicious anemia] and folic acid deficiencies), myelodysplastic anemias (e.g., from cancer chemotherapy), and liver disease (e.g., alcoholism).
- Normocytic anemias are characterized by RBCs within the normal size range (mean corpuscular volume, 80 to 98 fL) and include anemias of acute blood loss, acquired and inherited hemolytic anemias (e.g., sickle-cell anemia), mixed micro-macrocytic anemias, and anemias related to renal failure and bone marrow disease. Read the rest of this entry »
Tags: Anemia
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Written by dedy on 28 June 2008
Definition
Anaphylaxis, meaning “without protection,” is a systemic, potentially life-threatening hypersensitivity reaction. It occurs abruptly and variably, as a result of an IgE-mediated release of histamine and other mediators from mast cells and basophils in previously sensitized individuals. The severe allergic response is a medical emergency and is estimated to be responsible for more than 500 deaths annually. Anaphylactoid reactions (sometimes called pseudoanaphylaxis) present clinically like anaphylaxis, but their mechanism is not IgE-mediated. Also, unlike a hypersensitivity reaction, they tend to occur following initial exposure to an offending agent by direct toxic effect to cell mediators or indirect activation of the complement cascade. Read the rest of this entry »
Tags: Anaphylaxis
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Written by dedy on 28 June 2008
Definition
Amyloidosis describes a heterogeneous group of diseases, all characterized by the extracellular deposition of fibrillar, proteinaceous material in organs and tissues, either locally or systemically. The following four major classes of systemic amyloidosis are differentiated by the nature of the precursor plasma proteins that form the fibril deposits:
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Immunoglobulin light chain or “primary” amyloidosis (AL) (associated with monoclonal plasma cell dyscrasias; the most common form of systemic amyloidosis; also known as primary idiopathic amyloidosis)
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Reactive or secondary amyloidosis (AA) (associated with chronic inflammatory disease)
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Hereditary amyloidosis (an autosomal dominant group of diseases, each associated with gene mutations producing different proteins)
- Beta2-microglobulin amyloidosis (associated with long-term dialysis for chronic renal failure)
Localized amyloid deposits are restricted to specific tissues in certain diseases. These include:
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Polypeptide hormone-derived amyloidosis (seen in over 90% of type II diabetes mellitus patients; also seen in the case of medullary carcinoma of the thyroid and other endocrine tumors; approximately 80% of adults over age 80 have this type of deposition in the sarcolemma)
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Amyloidosis associated with Alzheimer’s disease and Down’s syndrome as well as hereditary cerebral hemorrhage with amyloidosis (all caused by a beta-amyloid protein, betaAP)
- Diseases caused by scrapie-associated prion proteins (Creutzfeldt–Jakob disease, kuru, and Gerstmann–Straussler syndrome)
Isolated deposits may be seen in any organ or tissue site. Read the rest of this entry »
Tags: Amyloidosis
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Written by dedy on 28 June 2008
Definition
Amenorrhea is the absence of menses. Primary amenorrhea is defined as the failure of menses to begin once a woman reaches 16 years of age, whether or not other pubertal changes such as breast development/pubic or axillary hair are present. Secondary amenorrhea is the absence of menses for the length of time equal to three consecutive normal menstrual cycles in a woman who has previously experienced cyclical menses. Interference with hypothalamic/pituitary functioning plays a major role in the disorder, and the resultant “hypoestrogenemic amenorrhea” may play a role in the development of cardiovascular disease, osteoporosis, and infertility. Amenorrhea may be present with other conditions or abnormalities, including hirsutism, obesity, and galactorrhea. Incidence of primary amenorrhea in U.S. is 2.5% of female population. Read the rest of this entry »
Tags: Amenorrhea
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Written by dedy on 28 June 2008
Definition
Alzheimer’s disease (AD) is the most common cause of dementia in the elderly, affecting at least three to four million people in the United States. AD is defined as memory loss with at least one other area of cognitive impairment (e.g., language, attention, orientation, self-monitoring, judgment, motor skill, inability to perform daily activities). Memory loss typically begins at about age 65 and slowly progresses to severe impairment over 8 to 10 years, but it may present sooner and advance at a different rate. Language deficits are prominent, including word finding (especially nouns), comprehension, repetition, and fluency. Social graces, which may remain surprisingly intact for years, eventually deteriorate to a loss of inhibition with periods of aggression or withdrawal. Personality and behavioral changes as well as problems in judgment occur with increasing severity. Death usually occurs from malnutrition, heart disease, or infection. Clinical diagnosis cannot be definitively confirmed without autopsy. Read the rest of this entry »
Tags: Alzheimer's disease
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Written by dedy on 28 June 2008
Definition
Alopecia is the absence or thinning of hair in an area of the body where hair formerly grew. It may be caused by physical damage to the hair itself or to the hair follicles, but is most often the result of changes in the natural hair growth cycle.
The average scalp has about 100,000 hairs. Most of these hairs are in the anagen, or growing, phase, which may last as long as five years. In the catagen, or transitional, phase, the hair stops growing and the follicle begins to shrink. The hair then falls out and the follicle lies dormant in the telogen, or resting, phase until a new anagen phase begins. About 10% of the hair follicles on the normal scalp are in the transitional or resting phases, and about 100 hairs are lost every day. In some types of alopecia, the growth cycle is disrupted by some temporary situation such as a chemical imbalance or stress; often the problem may be resolved when the precipitating condition is alleviated. However, 95% of cases of hair loss in both men (male pattern baldness) and women (female diffuse baldness) are genetic in origin. This is called androgenetic alopecia. Read the rest of this entry »
Tags: Alopecia
Posted in Medical | 1 Comment »
Written by dedy on 28 June 2008
Definition
Allergic rhinitis (hay fever) is a reaction to airborne allergens. It affects between 1:6 and 1:10 Americans and is an IgE-mediated disorder of the immune system; 70% of cases occur before age 30. Symptoms resemble those of viral rhinitis but persist and show seasonal variation. This most common form of allergy involves the entire respiratory system—nasal cavity, mouth, throat, bronchi, lungs, and diaphragm. There is an inherited tendency, with a child having a 50% chance of developing such allergy if one parent is allergic and a 75% chance if both parents are allergic. Read the rest of this entry »
Tags: Allergic rhinitism, hay fever
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