Pituitary magnetic resonance imaging (MRI) revealed a 3.5 mm microadenoma and inferior petrosal sinus sampling of adrenocorticotropic hormone (ACTH) after corticotropin releasing hormone (CRH) stimulation confirmed ACTH-dependent CD.
Its diagnosis relies on both biochemical tests (high-dose dexamethasone suppression test, ACTH level, corticotropin-releasing hormone test) to confirm ACTH-dependent CD and image studies (CT or MRI of chest, abdomen, and/or pelvis) for source localization.
IPSS with desmopressin is a sensitive approach in the diagnosis of CD and has moderate accuracy in tumour lateralization, making it an alternative choice to IPSS with CRH.
Investigations suggested Cushing's disease; there was suppression after high-dose dexamethasone (<20 nmol/liter) and a 950% increase in ACTH after stimulation with CRH.
Based on existing data, the desmopressin test is regarded as an alternative to the CRH stimulation test and, when given in combination with CRH, it has been suggested to completely discriminate between patients with CD and EAS.