Clinical and analytical evaluation of an immunoradiometric assay for corticotropin

Thomas G. Rosano, Laurence M. Demers, Robyn Hillam, Marian T. Dybas, Matthew Leinung

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


We evaluated a new IRMA developed commercially for the measurement of corticotropin (ACTH) in human plasma. The assay involves purified polyclonal goat capture antibodies specific for ACTH 26-39 and an 125I-labeled monoclonal signal antibody specific for ACTH 1-17. CVs for intraassay and total precision at ACTH concentrations between 9 and 801 ng/L ranged from 2.5% to 4.7% and from 3.3% to 9.3%, respectively, with an assay detection limit of 1.7 ng/L. The reference interval determined for adults with the new method (16-52 ng/L) differed significantly (P <0.05) from that for an established ACTH IRMA (9-54 ng/L). Method comparison with clinical samples (n = 179) revealed a correlation coefficient of 0.970 and a best-fit equation of y (new IRMA) = (1.011 ± 0.019)x + (4.17 ± 3.31) with S(y/x) = 40.2. Both methods showed equivalent clinical sensitivity in evaluating Cushing disease, adrenal tumors, ectopic ACTH-producing tumors, hypopituitarism, steroid suppression, surgical adrenalectomy, Nelson syndrome, Addison disease, and corticotropin-releasing hormone stimulation. We conclude that the new IRMA is technically simple to perform and provides a specific and sensitive method for evaluating of adrenocortical function.

Original languageEnglish (US)
Pages (from-to)1022-1027
Number of pages6
JournalClinical chemistry
Issue number7
StatePublished - 1995

All Science Journal Classification (ASJC) codes

  • General Medicine


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