Determination of cortisol cut-off limits and steroid dynamics in the ACTH stimulation test: a comparative analysis using Roche Elecsys Cortisol II immunoassay and LC-MS/MS

Measurement of cortisol concentrations is method dependent. The study aimed to establish assay-specific cut-off limits for cortisol after adrenocorticotropic hormone (ACTH) stimulation, comparing Roche Elecsys Cortisol II immunoassay to liquid chromatography-mass spectrometry (LC-MS/MS), and to assess the impact of patient characteristics, estrogen containing oral contraceptives as well as relation to other adrenocortical steroid hormone dynamics. One hundred healthy participants underwent a 250 μg ACTH-test, with plasma samples analyzed using ElecsysCortI, ElecsysCortII, and LC-MS/MS. Cortisone, corticosterone, 17-OH-progesterone, dehydroepiandrosterone sulfate (DHEAS), androstenedione, and testosterone were additionally analyzed with LC-MS/MS. Cut-off limit for a normal cortisol response to the ACTH-test was defined as: 2.5th percentile–1.96 × SE. ElecsysCort II measured cortisol concentrations 21