6447 Delayed Presentation Of Primary Hyperaldosteronism In The Setting Of An Adrenal Incidentaloma

Disclosure: S.K. Devineni: None. J.L. Gilden: None. Background: Current guidelines for biochemical monitoring in the setting of an adrenal incidentaloma suggest annual laboratory testing up to 4 years. If there is no progression in size and phenotype of adrenal mass, no further workup is generally recommended after 4 years. However, we present a case of delayed primary hyperaldosteronism development nearly 10 years after an adrenal lesion was diagnosed. CASE: A 71-year-old Filipino male was referred to the Endocrinology clinic for evaluation of an incidental finding of an adrenal mass in 2010. Initial imaging showed a right adrenal nodule measuring 1.1 cm with washout and Hounsfield units consistent with a benign adenoma. Biochemical laboratory testing was normal at that time. Family history is relevant for a biological brother who had an unknown type of adrenal tumor that was removed in middle age. Pertinent medical history included essential hypertension, well controlled at that time on dual antihypertensive therapy. Surveillance imaging and laboratory testing were continued annually per guidelines for the next 4 years and were normal. In 2016, nearly 6 years after initial diagnosis of adrenal lesion, patient’s blood pressure worsened thus his PCP added a third antihypertensive medication. At that time, repeat hormonal testing and imaging to rule out secondary hypertension etiologies were normal. Blood pressure remained stable but again started to rise in 2020, thus a fourth antihypertensive medication was added to his regimen. Biochemical evaluation now showed serum aldosterone-to-renin ratio (ARR) increased from normal level (less than 30) to 48, with up-trending aldosterone levels. Patient’s serum ARR continued to rise over the course of the following year (now 11 years from initial diagnosis of adrenal lesion) with levels increasing to 100, up to a peak level of 142. CT adrenal imaging showed bilaterally nodular adrenal glands with an unchanged 1.1 cm right adrenal nodule with absolute washout of 74.8% as well as a new right adrenal lesion measuring 2.0 cm with absolute washout of 65.8%. Due to these imaging findings, decision was made to substitute spironolactone therapy for one of his four antihypertensive medications. Patient remains biochemically and clinically stable and is awaiting adrenal venous sampling for determination of hormonal activity of adrenal lesions. CONCLUSION: We present a rare clinical scenario where an adrenal incidentaloma may be hormonally active nearly a decade after initial diagnosis with a delayed presentation of primary hyperaldosteronism. We hope this case sheds light on considerations for extended surveillance and monitoring of adrenal incidentalomas in the setting of worsening hypertension. Presentation: 6/2/2024