Tumour lateralization in Cushing's disease by inferior petrosal sinus sampling with desmopressin

Bilateral inferior petrosal sinus sampling (IPSS) with corticotropin-releasing hormone (CRH) is currently the gold standard in the diagnosis of Cushing's disease (CD) and has also been used in tumour lateralization. Our objective was to determine the diagnostic value and lateralization accuracy of IPSS with desmopressin.

We retrospectively analysed 91 patients with Cushing's syndrome who had either negative findings on pituitary dynamic enhanced magnetic resonance imaging (MRI) or nonsuppressed high-dose dexamethasone suppression tests (HDDST). Thin-slice thoracoabdominal computed tomography (CT) and octreotide receptor imaging of whole body were also negative to rule out ectopic adrenocorticotropin hormone (ACTH) syndrome. All patients went through IPSS with desmopressin. Afterwards, transsphenoidal pituitary surgery, light microscope pathology and immunohistological staining for ACTH were performed in all patients.

Diagnosis of CD. Among the 91 patients included, 90 were confirmed with CD, of whom 89 had positive IPSS findings, therefore the sensitivity was 98.9%. The one patient who was negative for CD also had negative IPSS findings, therefore the specificity was 100%. Tumour lateralization. Among the 51 patients who were ultimately diagnosed with CD and whose lateralization by IPSS and surgery was either left or right, 37 had IPSS lateralization in concordance with surgery, therefore the concordance rate was 72.5%. Patients in the concordant group had a higher frequency of right lateralization by surgery.

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.