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[rey-dee-oh-im-yuh-noh-as-ey, -a-sey, -i-myoo-] /ˌreɪ di oʊˌɪm yə noʊˈæs eɪ, -æˈseɪ, -ɪˌmyu-/
a test procedure that integrates immunologic and radiolabeling techniques to measure minute quantities of a substance, as a protein, hormone, or drug, in a given sample of body fluid or tissue.
Origin of radioimmunoassay
1960-65; radio- + immunoassay Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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British Dictionary definitions for radioimmunoassay


a sensitive immunological assay, making use of antibodies and radioactive labelling, for the detection and quantification of biologically important substances, such as hormone concentrations in the blood
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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radioimmunoassay in Medicine

radioimmunoassay ra·di·o·im·mu·no·as·say (rā'dē-ō-ĭm'yə-nō-ās'ā, -ĭ-myōō'-)
Abbr. RIA
The immunoassay of a substance, such as a hormone or an enzyme that has been radiolabeled.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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radioimmunoassay in Science
  (rā'dē-ō-ĭm'yə-nō-ās'ā, -ĭm-y'-)   
An immunoassay in which the substance to be identified or quantified is labelled with a radioactive substance (called a tracer), such as an ion. See also immunoassay, tracer.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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