BILATERAL SEQUENTIAL INFERIOR PETROSAL SINUS SAMPLING WITH CORTICOTROPIN-RELEASING HORMONE STIMULATION IN THE DIAGNOSIS OF CUSHINGS-DISEASE

Objective: The demonstration of a central to peripheral ACTH gradient in a hypercortisolaemic patient is diagnostic of Gushing's disease. We tried to determine whether single blood samples for ACTH obtained seq uentially from each of the inferior petrosal sinuses following human c orticotrophin-releasing hormone (hCRH) stimulation can reliably establ ish such a gradient. Design: Prospective study. Patients: Seventeen pa tients with clinical and biochemical features of Gushing's syndrome. M ethods: After the administration of hCRH, the patients underwent bilat eral sequential inferior petrosal sinus sampling, with a single blood sample obtained from each of the inferior petrosal sinuses sequentiall y, along with a peripheral venous sample. The petrosal sinus catheter was withdrawn immediately after obtaining a blood sample. Patients did not require indwelling catheters in the petrosal sinuses, nor heparin isation. Results: Bilateral sequential inferior petrosal sinus samplin g correctly identified a pituitary source of ACTH, as shown by a centr al to peripheral ACTH ratio >2, in all patients in whom the procedure was successfully carried out. All patients underwent transsphenoidal p ituitary surgery resulting in remission. Conclusions: The simplified m ethod of inferior petrosal sinus sampling, using a single sequential s ample from each of the inferior petrosal sinuses, following initial hC RH stimulation, is as accurate as the more complex test using multiple bilateral simultaneous inferior petrosal sinus samples. It avoids the use of indwelling cerebral venous catheters and is therefore unlikely to cause brain stem damage.