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Parallel Radioimmunoassay for Plasma Cortisol and 11-Deoxycortisol

Parallel Radioimmunoassay for Plasma Cortisol and 11-Deoxycortisol Abstract We describe a direct, rapid, and specific procedure for the parallel radioimmunoassay for cortisol and 11-deoxycortisol in plasma. The plasma sample is used directly, after heat inactivation of the natural cortisol-binding protein. The radioimmunoassay utilizes antibodies generated in rabbits by steroids conjugated at their 3-oxo position to thyroglobulin. Ammonium sulfate is used to separate bound and free steroids. Our cortisol antibody and an 11-deoxycortisol antibody obtained elsewhere cross reacted negligibly with each other or with other steroids that might be present in plasma. Radioimmunoassays were therefore developed for both steroids in only 1.25 µl of plasma. The intra-and interassay coefficients of variation for both steroids were less than 10%, with a sensitivity of 4 µg/liter. Steroid values obtained by a competitive protein binding method were consistently higher than those of the present method, suggesting that the former is measuring total corticosteroids. This simple approach requires only 4 h for the specific measurement of both cortisol and 11-deoxycortisol in 20 samples of plasma This content is only available as a PDF. © 1975 The American Association for Clinical Chemistry, Inc. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Clinical Chemistry Oxford University Press

Parallel Radioimmunoassay for Plasma Cortisol and 11-Deoxycortisol

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References (23)

Publisher
Oxford University Press
Copyright
© 1975 The American Association for Clinical Chemistry, Inc.
ISSN
0009-9147
eISSN
1530-8561
DOI
10.1093/clinchem/21.11.1644
Publisher site
See Article on Publisher Site

Abstract

Abstract We describe a direct, rapid, and specific procedure for the parallel radioimmunoassay for cortisol and 11-deoxycortisol in plasma. The plasma sample is used directly, after heat inactivation of the natural cortisol-binding protein. The radioimmunoassay utilizes antibodies generated in rabbits by steroids conjugated at their 3-oxo position to thyroglobulin. Ammonium sulfate is used to separate bound and free steroids. Our cortisol antibody and an 11-deoxycortisol antibody obtained elsewhere cross reacted negligibly with each other or with other steroids that might be present in plasma. Radioimmunoassays were therefore developed for both steroids in only 1.25 µl of plasma. The intra-and interassay coefficients of variation for both steroids were less than 10%, with a sensitivity of 4 µg/liter. Steroid values obtained by a competitive protein binding method were consistently higher than those of the present method, suggesting that the former is measuring total corticosteroids. This simple approach requires only 4 h for the specific measurement of both cortisol and 11-deoxycortisol in 20 samples of plasma This content is only available as a PDF. © 1975 The American Association for Clinical Chemistry, Inc. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Journal

Clinical ChemistryOxford University Press

Published: Oct 1, 1975

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