SUN-244 - Characterization of Primary Aldosteronism based on Adrenal Venous Sampling and Computed Tomography results

Introduction: Primary aldosteronism (PA) is the most common cause of endocrine hypertension characterized by elevated aldosterone with suppressed renin. Accurate subtype classification is essential to guide definitive therapy. Adrenal venous sampling (AVS) is the gold standard for subtype classification, but is technically demanding, expensive, and available only at specialized centers with experienced interventional radiologists. In contrast, adrenal computed tomography (CT) is widely accessible, however it has lower diagnostic accuracy, with reported sensitivity and specificity of approximately 67% and 60%. The diagnostic performance of these modalities at our institution had not been previously evaluated.

Methods: We conducted a retrospective cohort study of patients who underwent AVS for PA at a tertiary center (2014–2025). Procedural success required a selectivity index ≥5 bilaterally. Disease subtype was defined by lateralization index (LI): unilateral (LI ≥4) or bilateral (LI < 4). CT findings were categorized as unilateral or bilateral based on structural abnormalities, or as normal. The primary outcome was CT diagnostic performance for subtype classification using AVS as the reference standard. Secondary analyses compared procedural, clinical and biochemical characteristics between AVS-defined groups. Statistical significance was set at p< 0.05.

Results: Among 337 patients who underwent AVS, 315 (93.4%) had a successful procedure, with cosyntropin used in 95% of procedures (mean age 52.6 ± 12.2 years; 60.6% male; 96.2% with hypertension). Bilateral disease (non-lateralizing) was identified in 126 (40%), unilateral disease in 189 (60%; 94 right, 95 left). Unilateral (lateralizing) PA was associated with higher plasma aldosterone (32.2 vs. 24.4 ng/dL; p< 0.001), higher aldosterone-to-renin ratio (21.4 vs. 6.7; p< 0.001), and more frequent potassium supplementation (87.6% vs. 72.6%; p< 0.001). Among 306 patients with both AVS and CT, CT sensitivity was 59.1% (95% CI 51.7–66.3) for unilateral disease and only 15.8% (95% CI 9.8–23.6) for bilateral disease. CT was interpreted as normal in 31.7% of bilateral and 11.3% of unilateral cases. A contralateral suppression index (CSI) < 1 was present in 88% of left-unilateral and 89% of right-unilateral cases. Among patients with LI >4 and CSI >1, 52% were treated with MRAs, 10% with adrenalectomy, 36% with combination therapy compared to 14%, 26%, and 59% respectively in those with CSI < 1.

Conclusion: Our findings highlight the limitations of CT imaging alone for subtype classification as previously reported in the literature. Given that treatment strategies differ substantially between lateralizing and non-lateralizing disease, reliance on CT alone could lead to inappropriate management decisions. Expanded access to AVS, or development of reliable non-invasive alternatives such as new nuclear studies, is urgently needed.

*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.*