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the first letter of the Greek alphabet, α; used to denote the first position in a classification system; as, in names of chemical compounds, to distinguish the first in a series of isomers, or to indicate the position of substituent atoms or groups; also used to distinguish types of radioactive decay, brain waves or rhythms, adrenergic receptors, and secretory cells that stain with acid dyes, such as the alpha cells of the pancreas.
alpha-adrenergic blocking agent (alpha-blocker) (alpha-blocking agent) any of a group of drugs that selectively inhibit the activity of alpha receptors in the sympathetic nervous system. As with beta-adrenergic blocking agents, alpha-blocking agents compete with the catecholamines at peripheral autonomic receptor sites. This group includes ergot and its derivatives, and phentolamine.
alpha chain disease the most common heavy chain disease, occurring predominantly in young adults in the Mediterranean area, and characterized by plasma cell infiltration of the lamina propria of the small intestine resulting in malabsorption with diarrhea, abdominal pain, and weight loss, or, exceedingly rarely, by pulmonary involvement. The gastrointestinal form is immunoproliferative small intestine disease.
alpha-fetoprotein (AFP) a plasma protein produced by the fetal liver, yolk sac, and gastrointestinal tract and also by hepatocellular carcinoma, germ cell neoplasms, and other cancers in adults; elevated levels may also be seen in benign liver disease such as cirrhosis and viral hepatitis. The serum AFP level is used to monitor the effectiveness of cancer treatment.

During pregnancy some AFP crosses from the amniotic fluid to the mother's blood. If the fetus has a neural tube defect, large amounts of AFP will be found in the amniotic fluid and maternal blood. Blood screening tests for serum AFP can thus be done as a first step in the screening process; if test results are positive, further testing is indicated to diagnose the defect.
alpha particles a type of emission produced by the disintegration of a radioactive substance. The atoms of radioactive elements such as uranium and radium are very unstable, continuously breaking apart with explosive violence and emitting particulate and nonparticulate types of radiation. The alpha particles, consisting of two protons and two neutrons, have an electrical charge and form streams of tremendous energy when they are released from the disintegrating atoms. These streams of energy (alpha rays) can be used in treatment of various malignancies. See also radiation and radiation therapy.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


(ăl′fə-fē′tō-prō′tēn, -tē-ĭn)
n. Abbr. AFP
An antigen produced in the liver of a fetus and that is also present in certain diseases, such as liver cancer. Its level in amniotic fluid can be used to detect certain fetal abnormalities, including Down syndrome and spina bifida.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


A gene on chromosome 4q11-q13 that encodes alpha-fetoprotein, a major plasma protein produced by the yolk sac and the liver during foetal life. AFP is regarded as the foetal counterpart of serum albumin and binds copper, nickel, fatty acids and bilirubin; hereditary persistance of alpha-fetoprotein may be found in individuals with no obvious pathology.

Molecular pathology
AFP is elevated in foetuses with neural tube defects, including spina bifida and anencephaly. It is elevated in adults with hepatocellular carcinomas and germ cell tumours.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.


Fetoglobulin Clinical chemistry A 70 kD glycoprotein, synthesized by the embryonic yolk sac, fetal GI tract and liver, which has 40% homology with albumin, which peaks at 13 wks of fetal age; AFP's role in fetal development is unclear; AFP levels are measured in pregnancy to screen for open neural tube defects–incidence, 1-2/1000 births and for Down syndrome, and in adults to detect liver cancer and germ cell tumors Ref range Non-pregnant adults < 30 ng/mL; maternal serum–13-16 wks, < 1.0-4.4 µg/dL; amniotic fluid–13-16 wks, 0.9-4.1 mg/dL AFP levels in fetal serum are 150-fold > amniotic fluid, which in turn are 200-fold > maternal serum; maternal serum levels are 300-400 µg/L in the 3rd trimester; AFP levels in fetal serum and amniotic fluid peak at 13 wks, while the maternal levels peak at 30 wks; AFP in pregnancy is > in twins and higher multiple pregnancies; if the fetal neural tube fails to close completely, large quantities of AFP enter the amniotic fluid, resulting in ↑ levels in the mother's serum; confirmatory tests such as amniocentesis and/or ultrasonography are used to identify neural tube defects is elevated; after the immediate postnatal period, ↑ serum AFP levels occur only with conditions of abnormal cell multiplication; although AFP measurement is not FDA-approved for cancer screening, in practice, it is used to both detect and monitor therapy in liver cell cancer and germ cell tumors of gonadal, retroperitoneal, or mediastinal origin. See Liver cell carcinoma, Triple screen.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

Alpha-fetoprotein (AFP)

A substance produced by a fetus' liver that can be found in the amniotic fluid and in the mother's blood. Abnormally high levels of this substance suggests there may be defects in the fetal neural tube, a structure that will include the brain and spinal cord when completely developed. Abnormally low levels suggest the possibility of Down' syndrome.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
The mean serum Alfa fetoprotein level was 7641.03665.32 IU/ml.
Conclusion: Serum Alfa fetoprotein levels were a useful tool for the detection of hepatocellular carcinoma in hepatitis C virus patients.
Meningomiyeloseller deri ile ortulu olduklarinda Alfa fetoprotein duzeyleri normal saptanir bu nedenle gebelik oncesi ultrasonografi onem kazanmistir (4,5).
Magnetic resonance imaging and serum alfa fetoprotein have been used to diagnose abdominal pregnancy (9, 10) however there was no justification to perform these tests in this patient as the diagnosis was not suspected.
No statistically significant association was observed with age, gender, presence of co-morbids, basal total bilirubin, platelet levels, transaminases, albumin, sodium, creatinine, alfa fetoprotein, Okuda stage, CTP score or MELD score.
On the basis of alfa fetoprotein level patients were divided in to 3 groups; Group I with normal AFP ( less than 20IU/ml), Group II with moderately elevated AFP (20-399IU/ml), and Group III with markedly elevated AFP ( greater than 400 iu/ml).