The Role of ACTH in Adrenal Vein Sampling: Experience at Two Tertiary Hospitals

Presentation Number: SUN 510
Date of Presentation: April 2nd, 2017

Azni Lihawa Abdul Wahab*1, Nicholas Yong Nian Chee2, James Doery2, Kay Weng Choy3, Winston Chong4, Peter J Fuller4, Cherie Ying Chiang5 and Jun Yang6
1Austin Health, Heildelberg, Australia, 2Monash Health, Melbourne, Australia, 3Monash Health, Melbourne, AUSTRALIA, 4Monash Health, Victoria, Australia, 5Austin Health, Heidelberg, Australia, 6Monash Health, Clayton, Victoria, Australia

Abstract

Objective:

Adrenal vein sampling (AVS) is crucial for differentiating between unilateral and bilateral causes of primary aldosteronism (PA). However, there is a lack of uniform agreement regarding the use of adrenocorticotropic hormone (ACTH) stimulation during AVS. This study compares basal and post-ACTH aldosterone and cortisol values to evaluate the role of ACTH stimulation in AVS.

Methods:

An audit was conducted of 127 AVS procedures performed at Austin Health (Jan 2001–Dec 2015) and Monash Health (Jan 2010-Dec 2015). Both centres performed AVS pre- and post-ACTH using sequential catheterization. Patient demographics, screening aldosterone and renin concentrations, AVS aldosterone and cortisol levels pre- and post-ACTH stimulation, adrenal imaging and surgical outcomes including adrenal histology were retrieved. Successful cannulation and lateralization were defined by the selectivity index (SI) and the lateralization index (LI) respectively. Suppression of the non-dominant adrenal site was defined as contralateral suppression index (CSI) <1.

Results:

ACTH significantly increased the rate of successful cannulation (SI > 2 pre- or > 3 post-ACTH), from 70% to 95% on the left (p<0.001), and from 54% to 68% on the right (p=0.029). However, ACTH stimulation significantly lowered the LI (p=0.03). Using LI> 3 pre-ACTH and LI > 4 post-ACTH as thresholds for lateralization, the number of unilateral cases decreased from 71% pre-ACTH to 52% post-ACTH. 6 cases were discordant, whereby the cases would have been re-classified as bilateral despite basal lateralization. Despite being discordant, all underwent unilateral adrenalectomy, 4 of those had adrenal adenomas confirmed on histology and had clinical improvement and normalization or improvement in blood pressure. All 4 patients had post-ACTH LI > 2 and basal CSI<1.

Conclusion:

ACTH stimulation increased the rate of successful cannulation in AVS but masked lateralization in four cases of proven adenoma. Basal LI appears to be the more robust in predicting histological and clinical outcome of surgery, although a post-ACTH LI using a lower threshold of >2 also supports the diagnosis of an aldosterone-producing adenoma. CSI was also useful in making the surgical decision.

 

Nothing to Disclose: ALA, NYN, JD, KWC, WC, PJF, CYC, JY