Abstract Disclosure: A. Attre: None. A. Syeda: None. A. Khan: None. B. Esayag-Tendler: None. Dynamic Clinical Evolution: Why Patients Require Long-Term Follow-up Over Time Introduction Primary Hyperaldosteronism (PHA) is an increasingly recognized cause of secondary hypertension amenable to specific therapy. We describe a case of PHA with change in management trajectory over time. Case A 48-year-old woman was diagnosed with PHA in 2009 based on an aldosterone level of 42.7 ng/dL, plasma renin activity of <0.1 ng/mL/hr, and a low potassium of 3.4 mmol/L. At that time, simultaneous adrenal venous sampling (AVS) had revealed a bilateral etiology of aldosterone excess. Original imaging with CT scan had shown fullness on both adrenal glands, and she was treated with 50mg daily spironolactone. Follow-up with CT scan in 2018 revealed similar imaging phenotype. When she established care with us in 2020, the abdomen MRI revealed a 2.5 cm x 1.9 cm right adrenal nodule. In addition, the blood pressure readings were noted to be high despite increasing doses of spironolactone to 150mg. Her laboratory results revealed aldosterone 151 ng/dL [< 31 ng/dL], cortisol 0.8 µg/dL, plasma renin activity 0.8 ng/mL/hr [0.2 ng/mL/hr - 1.6 ng/mL/hr], ACTH 12.5 pg/mL [7.2 pg/mL - 63.3 pg/mL], normal plasma metanephrine and a normal thyroid panel. A decision was made to repeat AVS in 2023 following Dr. Doppman’s protocol. The patient’s spironolactone was held before AVS and the plasma renin activity before the procedure was 0.4-0.8 ng/mL/hr. Results: Repeat AVS in 2023 showed mean pre-ACTH right to left lateralization index (LI) of 29.9 and mean post-ACTH LI of 9.7 (cutoff >4). This is concordant with the right adrenal nodule noted on imaging. The selectivity index confirmed adequate adrenal venous sampling data. Analysis of our findings confirmed right adrenal excess and left adrenal suppression compared to the IVC results. This patient underwent a laparoscopic right adrenalectomy in 2023. This patient's aldosterone levels were measured two days postoperatively and were found to be 4.2 ng/dL, showing immediate improvement. Six months postoperatively, our patient’s home and clinic blood pressures are in 120s/60s mmHg range without any medications. The aldosterone remains less than 6 ng/dL and the plasma renin activity is no longer low. Her potassium remains around 4.9 mmol/L. Discussion Based on current literature, surgical treatment is preferred when there is a confirmed unilateral cause of PHA. Adrenalectomy is recommended in patients with confirmed unilateral hyperaldosteronism especially when they do not achieve clinical and biochemical goals (renin plasma activity >1 ng/mL/hr, resolution of hypokalemia and optimal BP control) despite the use of MRA at appropriate doses. Suppressed renin is known to be associated with increased cardiovascular morbidity. This case serves as an important example of the need to follow patients long-term because PHA is a dynamic clinical entity that affects quality of life. Presentation: 6/3/2024