Bilateral inferior petrosal sinus sampling in the diagnosis of ACTH-dependent Cushing's syndrome: experience in a tertiary hospital.

OBJECTIVES: Bilateral inferior petrosal sinus sampling (BIPSS) is a useful test for differential diagnosis of central vs. ectopic adrenocorticotropic hormone (ACTH)-dependent Cushing's syndrome (CS). We provide a description of the protocol used in our Center and an analysis of its diagnostic accuracy.

METHODS: A retrospective study was conducted of 28 patients who underwent BIPSS combined with corticotropin-releasing hormone (CRH) stimulation. The procedure is performed in an interventional neuroradiology suite, involving a multidisciplinary team of neuroradiologists, endocrinologists and laboratory professionals. The two petrosal sinuses are catheterized and a peripheral blood sample is obtained simultaneously, at baseline and at 3, 6 and 10 min following stimulation. ACTH and prolactin are determined by immunochemiluminescence.

RESULTS: A total of 19 cases of Cushing's disease (CD) and 1 case of ectopic CS were confirmed. In all cases, BIPSS provided accurate diagnostic guidance, with a sensitivity and specificity of 100%. In 8 patients, remission was not achieved after surgery. In 84% of catheterizations, ACTH ratio peaked at 3-6 min following stimulation. Patients with histologically-confirmed CD exhibited higher sinus ACTH ratios and values. Prolactin ratio helped us identify and exclude 28.6% of the samples with inconsistent results.

CONCLUSIONS: In our series, BIPSS combined with CRH stimulation demonstrated to be a safe, effective procedure. Prolactin emerges as a useful marker of correct catheterization. The participation of a multidisciplinary team is essential.