Usefulness of multiple-site venous sampling in the treatment of adrenocorticotropic hormone-producing pituitary adenomas.

Background: While venous sampling for adrenocorticotropic hormone (ACTH) may be the most accurate way to establish a diagnosis of Cushing's disease, its usefulness for lateralization of adenomas is limited even in combination with simultaneous bilateral sampling methods. Therefore, to increase accuracy in predicting the lateralization of adenomas, we performed a trial in which we carried out simultaneous venous sampling from multiple sites of the cavernous sinus (CS) and inferior petrosal sinus (IPS). Here we report on the usefulness of our method in the correct tumor lateralization in patients with Cushing's disease.

Methods: Eighteen patients with Cushing's disease underwent simultaneous bilateral ACTH sampling. The samples were obtained from the anterior, middle, and posterior CS and the IPS. CS sampling after stimulation with corticotropin-releasing hormone (CRH) was also performed. The central-to-peripheral ACTH ratio (c/p ratio) was calculated using sampling data from each site; the lateralizing gradients (right versus left) were calculated using the c/p ratio. Instead of the conventional method where the lateralization gradient is based on sampling data from a single site, we used the distribution of the c/p ratio determined from multiple-site data.

Results: There was no significant difference in the mean lateralization gradient obtained from each set of sampling data (p > 0.05). With the conventional method, correct tumor lateralization was obtained in 50% of tumors in the IPS; 72.2 to 77.8% of tumors in the CS; and 77.8% of tumors in the middle CS after CRH. Our method using ACTH contour analysis based on multiple sites produced correct results in all 18 of the patients examined. The difference in correct calls between the conventional method and our method was significant (p < 0.05).

Conclusions: Multiple-site sampling of ACTH is valuable for lateralizing the adenoma in patients with Cushing's disease; it produces more correct results than does single venous sampling.