Internal jugular vein adrenocorticotropic hormone estimation for diagnosis of adrenocorticotropic hormone-dependent Cushing's syndrome: Ultrasound-guided direct jugular vein sample collection

AIM OF STUDY: To assess the utility of internal jugular vein (IJV) / peripheral adrenocorticotropic hormone (ACTH) gradient in determining the etiology of ACTH- dependent Cushing's syndrome. MATERIALS AND METHODS: Patients with ACTH-dependent Cushing's syndrome, (except children less than 12 years), had IJV blood collection under ultrasound guidance using a linear 7 MHZ probe. Blood was collected with a 21 G needle at the level of mandible with the patient in supine position. Six ml of blood was collected sequentially from right and left internal jugular veins for ACTH and prolactin estimation. Peripheral blood for ACTH and prolactin was taken from a previously placed IV cannula in the antecubital vein. RESULTS: Thirty patients (20 F, 10 M, age 14 to 50 yrs) were enrolled for this study. Source of ACTH excess was pituitary in 22, ectopic ACTH in 4, and unknown in 4 cases. Using an IJV: Peripheral ACTH ratio of ≥ 1.6, 15 out of 22 Cushing's disease patients were correctly identified. However, 1 out of 4 ectopic Cushing also had IJV: Peripheral ratio ≥ 1.6. Overall, it had sensitivity of 68% with specificity of 75% while MRI pituitary and HDDST had sensitivity of 86% and 59%, respectively, with specificity of 100% each. CONCLUSION: IJV: Peripheral ACTH gradient was observed in 68% of patients with Cushing's disease. Simultaneous IJV and peripheral sample collection with CRH stimulation may improve sensitivity and specificity of this test.