LAUSR

Abstract Disclosure: A. Attre: None. P. Sztachelski: None. A. Arigala: None. B. Esayag-Tendler: None. Introduction: Primary Hyperaldosteronism (PA) is a leading cause of secondary hypertension amenable to specific therapy. We describe a case of PA with contrasting findings on imaging and biochemical marker via simultaneous bilateral AVS contrast. Case: A 68-year-old man was diagnosed with PA based on an aldosterone level of 41.7 ng/dL, plasma renin activity of <0.1 ng/mL/hr, and a potassium of 3.4 mmol/L. A pre-AVS CT found a 1.5 cm low-attenuation (<10 HUs) nodule in the left adrenal gland with an unremarkable right adrenal gland. Results: The bilateral simultaneous pre- and post-ACTH adrenal venous sampling (AVS) in 2024 showed a right-to-left lateralization index (LI) of 15.70, discordant with the left adrenal nodule noted on imaging. The patient underwent a right adrenalectomy, and his post-operative aldosterone had decreased to 5.4 ng/dL. The pathology team identified a 1.3 cm right adrenal nodule that was not detected on the CT scan, providing confidence in the AVS findings. Discussion: This case provides an example of the criticality of AVS data in clinical decision-making, especially when imaging is discordant, inconclusive, or misleading. AVS provides quantitative evidence for aldosterone hypersecretion lateralization, which can be more telling than imaging alone. Of course, inaccuracies in AVS results can occur with poor supervision or deviations from standard protocols, so we urge colleagues to remain vigilant and exercise appropriate clinical judgment. This case also highlights the importance of supervising the protocol throughout the entire procedure, including collection, appropriate labeling of samples, and patient monitoring. Not all adrenal nodules in a patient with PA are functional, and it is important to rely on biochemical data. While medication management is common with the use of mineralocorticoid receptor antagonists, surgical management is recommended for cases of PA with a confirmed unilateral etiology. Presentation: Sunday, July 13, 2025