Useful for determining the cause of hypercortisolism and hypocortisolism
Lavender top (EDTA): deliver on ice
Specimen Collection / Processing Instructions
For the 12 hours before specimen collection do not take multivitamins or dietary supplements containing biotin (vitamin B7), which is commonly found in hair, skin, and nail supplements and multivitamins.
Morning (6 a.m.-10:30 a.m.) specimen is desirable.
Collect with a pre-chilled lavender top (EDTA) tube and transport to the laboratory on ice.
Centrifuge at refrigerated temperature within 2 hours and immediately separate plasma from cells.
Immediately freeze plasma.
Frozen (preferred): 28 days Refrigerated: 3 hrs Ambient: 2 hrs
Unacceptable Specimen Conditions
In very rare instances of the ectopic adrenocorticotropic hormone (ACTH) syndrome, the elevated ACTH may be biologically active but not detected by the immunometric assay.
Falsely elevated values may occur in plasma from patients who have developed human antimouse antibodies or heterophilic antibodies.
In rare cases, interference due to extremely high titers of antibodies to analyte-specific antibodies, streptavidin, or ruthenium can occur.
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 (LC-MS/MS) (eg, CINP / Cortisol, Serum, LCMS/MS) 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.