Background: Measuring plasma adrenocorticotropic hormone (ACTH) is a key step in the differential diagnosis of hypothalamic-pituitary-adrenal disorders.
Methods: The recently developed electrochemiluminescence Elecsys ACTH immunoassay (Roche Diagnostics, Mannheim, Germany) was evaluated at six clinical laboratories on the Modular E170 and/or the Elecsys 2010 (Roche Diagnostics) immunoanalysers.
Results: The within-run and between-run imprecision was <or=1.9% and <or=5%, respectively (concentration level 12-971 ng/L). Functional sensitivity was at least 1.8 ng/L. The Elecsys assay correlated well with two established ACTH immunoradiometric assays (Brahms ACTH RIA and Nichols ACTH IRMA) and with the Immulite ACTH assay. Reference values for the Elecsys ACTH assay, determined as the percentile 5 to 95 (2.5 to 97.5) interval in 354 adults without disorder with impact on the hypothalamic-pituitary-adrenal axis, were between 7.2 and 63 ng/L (5.6 and 76 ng/L). The clinical sensitivity of the Elecsys ACTH assay in 57 patients with confirmed disorders of the pituitary-adrenal axis was comparable to the established Brahms ACTH assay.
Conclusion: The non-isotopic Elecsys ACTH immunoassay provides precision and reliability in combination with reduced turnaround time.