Cautions

In very rare instances of the ectopic corticotropin (previously adrenocorticotropic hormone: ACTH) syndrome, the elevated ACTH may be biologically active but not detected by the immunometric assay.

In rare cases, some individuals can develop antibodies to mouse or other animal antibodies (often referred to as human anti-mouse antibodies [HAMA] or heterophile antibodies), which may cause interference in some immunoassays. The presence of antibodies to streptavidin or ruthenium can also rarely occur and may also interfere in this assay. Caution should be used in interpretation of results and the laboratory should be alerted if the result does not correlate with the clinical presentation.

Under ACTH 1-24 medication, ACTH measurement is not recommended, due to negative interference with the sandwich assay.

Patients taking glucocorticoids may have suppressed levels of ACTH with an apparent high level of cortisol. This may be due to cross-reactivity with the cortisol immunoassays. If exogenous Cushing is suspected, a cortisol level determined by liquid chromatography tandem mass spectrometry (eg, CINP / Cortisol, Mass Spectrometry, Serum) should be used with the ACTH level for the interpretation.

Values obtained with different assay methods or kits may be different and cannot be used interchangeably. Test results cannot be interpreted as absolute evidence for the presence or absence of malignant disease.