Endocrine Abstracts

Introduction: Adrenal vein sampling (AVS) is considered gold-standard for diagnosis of unilateral primary aldosteronism (PA), and necessary pre-surgery. Imaging-AVS discordance may occur in up to 30-40% of PA-AVS series, and presents a diagnostic dilemma which may preclude surgery. Lateralization by AVS is defined as the ratio of aldosterone concentrations normalized by cortisol from each adrenal vein, and is thus sensitive to any pathologic asymmetry in cortisol production. Unsuspected primary adrenal cortisol excess may explain cases of imaging-AVS discordance. Dynamic nuclear adrenal imaging could solve AVS-imaging discordance.

Methods: Retrospective study from the Calgary-AVS database, 2017-2023. Included patients had 1) biochemical and clinical presentation of PA with adrenal mass, 2) technically successful AVS with lateralization results discordant to cross-sectional imaging, and 3) dexamethasone-suppressed NP59-iodocholesterol adrenal scintigraphy. Concordance between cross-sectional imaging, AVS, and NP59 lateralization data was examined, as well as PASO-related outcomes for patients who ultimately underwent surgery.

Results: The database yielded 25 cases meeting the inclusion criteria. Despite discordant lateralization on AVS, functional lateralization with NP59 scanning was concordant with CT imaging in 80% of cases (20/25). 13 cases subsequently underwent surgical adrenalectomy (guided by CT-NP59 results) – in 62% of cases (8/13) the diagnosis after pathology and final biochemical and clinical outcomes was cortisol producing adenoma in bilateral (persistent) primary aldosteronism, while the final diagnosis in the remaining 38% of cases (5/13) was cortisol/aldosterone co-secreting adenoma with complete biochemical response. All cases had pre-operative low/suppressed ACTH with rise post adrenalectomy.

Conclusions: In cases of hypertension with adrenal mass and hyperaldosteronism, subtle cortisol excess may not be clinically recognized or meet biochemical thresholds of cortisol excess, yet may jeopardize the reliability of AVS, leading to treatment inertia, or inappropriate contralateral adrenalectomy. Functional nuclear imaging can be used to solve apparent discordance between adrenal anatomical abnormalities and unexpected AVS lateralization results.