The DiaSource ACTH-IRMA is a two-step immunoradiometric assay based on coated-tube separation.
It allows the determination of intact human adrenocorticotropic hormone (ACTH) in EDTA plasma. Monoclonal antibodies specific to the 1-24 ACTH fragment (N-terminal fragment) are attached to the lower and inner surface of the plastic tubes. Calibrators or samples are added to the tubes. After 2 hour incubation, washing removes the occasional excess of antigen, mid-regional and C-terminal fragments. 125I labelled polyclonal antibodies specific to the 24-39 ACTH fragment (Cterminal fragment) are added. After 1 hour incubation and washing the remaining radioactivity bound to the tube reflects the intact ACTH concentration.