FRI128 Hiding In Plain Sight: Late Diagnosis Of Primary Hyperaldosteronism In Patient With Atypical Presentation

Disclosure: R.A. Zielinski: None. A. Syeda: None. B. Esayag-Tendler: None. Background: Primary hyperaldosteronism (PHA) can go undiagnosed in patients with primary hypertension without hypokalemia and increased plasma aldosterone concentration (PAC). Case: The patient is a 72-year-old male with a history of hypertension (HTN) diagnosed at age 55 who presented to the endocrinology clinic for further evaluation. He was asymptomatic. His antihypertensive regimen included atenolol 25 mg daily and amlodipine-benazepril 10-40 mg daily. Blood pressure (BP) was well-controlled with a goal BP under 130/80 mm Hg. Physical exam was without AV nicking in a limited retina exam, no abdominal tenderness, and no peripheral edema. Family history is notable for HTN in his father and HTN complicated by stroke in a sister and a brother, all diagnosed at an older age. Labs done 5 years prior showed potassium (K) of 4.3 mmol/L [3.6 - 5.1 mmol/L], PAC of 3.2 ng/dl [upright 4.0 - 31.0 ng/dl], and plasma renin activity (PRA) of 0.1 ng/ml/hr [upright 0.5-4.0 ng/ml/hr]. More recent labs showed K of 3.8 mmol/L, PAC of 21.5 ng/dl and PRA of 0.3 ng/ml/hr. Repeat labs 6 months later showed K of 3.4 mmol/L, PAC of 15 ng/dL and PRA of 0.2 ng/mL/hr. A 3-day dexamethasone suppression test was performed to exclude familial hyperaldosteronism or glucocorticoid remediable aldosteronism. Following the test, K was 3.6 mmol/L, PAC was 11.3 ng/dl, and cortisol was undetectable. CT abdomen showed bilateral nodular thickening of the adrenal glands without a distinct adenoma. Adrenal venous sampling was done before and after ACTH stimulation. Prior to ACTH stimulation, the mean ratio of the dominant adrenal aldosterone concentration corrected with cortisol from left to right was 1.32. Following ACTH stimulation, the ratio was 2.79. A ratio greater than 4 is consistent with a good outcome after adrenalectomy. Hence, it was decided to pursue medical management. The cause of our patient’s primary hyperaldosteronism is likely due to bilateral idiopathic hyperplasia. He was started on eplerenone 25 mg twice daily and salt restriction with a goal of increasing the PRA above 1 ng/ml/hr. Discussion and Conclusion: It was initially thought that PHA represents 1% of all patients with primary HTN. However, more recent studies indicate that the prevalence is significantly higher. Additionally, the PAC in patients with PHA can fluctuate and patients can present with normokalemia, making the diagnosis more difficult to establish. It is an important diagnosis to establish and treat appropriately because there is a higher risk of cardiovascular morbidity and mortality in patients with PHA compared to patients with primary HTN. Presentation: Friday, June 16, 2023