Local Experience in Inferior Petrous Sinus Sampling

Background: Measurement of adrenocorticotropin levels in plasma from the inferior petrosal sinuses of patients with Cushing's syndrome can distinguish adrenocorticotropin-secreting pituitary tumors (Cushing's disease) from other causes of the syndrome, principally ectopic adrenocorticotropin secretion from an occult tumor.

Materials and Methods: We prospectively studied 54 patients with Cushing's syndrome to evaluate the diagnostic efficacy of the procedure. Bilateral sampling was successfully accomplished in 53 patients, with no major morbidity; all patients underwent sampling without administration of ovine CRH. The adrenocorticotropin levels in the samples were used to calculate the ratio of the concentration in plasma from the inferior petrosal sinuses to the concentration in peripheral-blood plasma (the IPS:P ratio).

Results: The diagnosis of 54 patients was confirmed surgically as Cushing's disease in 21, as ectopic adrenocorticotropin syndrome in 2, and 31 patients are waiting for surgery. An IPS:P ratio ≥2.0 in basal samples identified 21 of the 21 patients with Cushing's disease (sensitivity, 100%), with no false positive results (specificity, 100%). The sensitivity was much lower when the adrenocorticotropin concentrations in the samples from one sinus were considered alone. In patients with Cushing's disease a difference of ≥1.4-fold between the concentrations in the two sinuses (the adrenocorticotropin gradient) predicted the location of the microadenoma in 8% of 21 patients during basal sampling.

Conclusion: Simultaneous bilateral sampling of plasma from the inferior petrosal sinuses, even without the adjunctive use of CRH, may distinguishes patients with Cushing's disease from those with ectopic adrenocorticotropin secretion with high diagnostic accuracy.

Publication History

Article published online:
14 December 2021