SAT-462 Usefulness of Confirmatory Saline Loading Test in Diagnosing Primary Hyperaldosteronism among Patients Suspected for Cyclical or Periodic Excess Aldosterone Secretion

Abstract Disclosure: M.G. Famorcan: None. J.P. de Leon: None. F.C. Yap: None. J.Z. Lacson: None. J.V. Chua: None. J.L. Reyes: None. J.G. Sazon: None. J.F. Robles: None. L.B. Mercado-Asis: None. Background: Primary aldosteronism (PA) is responsible for 5–10% of all hypertension cases, with an even higher prevalence among patients with refractory hypertension. Precise evaluation of PA is crucial not only for optimizing medical therapy but also for diagnosing individuals who will benefit from surgery and thus prevent long-term adverse cardiovascular outcomes. However, single time-point testing may fail to detect patients with intermittent (cyclical/periodic) aldosterone secretion— a pattern well-documented in other endocrine hypersecretory disorders but not widely recognized in PA. Hence, the report of this case series. Cases: We are reporting three (3) cases with the clinical and hormonal features as follows: Case 1; 67 years old, female, Case 2; 51 years old, male, and Case 3; 24 years old, male. At initial consult the following were aged, 27, 35, and 17 years old, respectively. All manifested with high BP (150-190/90-120 mmHg) and hypokalemia (3.0-3.7 mmol/L). Case 1 was diagnosed with bilateral adrenal hyperplasia forty years ago and underwent unilateral adrenalectomy of the dominant side. In the interim, the patient was noncompliant with consult visits and discontinued her spironolactone that led to recurrence of symptomatology. Both Case 2 and Case 3 were referred for resistant hypertension and further work up. Cyclical or periodic excess aldosterone secretion was suspected because on initial basal hormonal tests all had nondiagnostic or equivocal ARR (Case 1; 5.0, Case 2; 5.0, Case 3; 17.0).With high clinical suspicion, saline infusion loading test was done. All yielded positive results with post-infusion plasma aldosterone concentration (PAC) value of >10 ng/dL (Case 1; 29.2, Case 2; 62.7, Case 3; 15.0) confirming the diagnosis of primary hyperaldosteronism. On repeat basal hormonal measurements only Case 1 showed increased ARR value of 22 while the other two (2) cases seemed to be in their lower scale of cyclicity with unsuppressed PRA (Case 2; 8.0, Case 3; 9.3 ng/mL/hr). With nondiagnostic CT scan findings, Case 2 underwent bilateral adrenal venous sampling (BAVS) with ACTH stimulation and underwent systemic hormonal unloading with unilateral adrenalectomy of the dominant side, a procedure done with Case 1 forty years ago. Histologic finding was adrenal hyperplasia. Case 1 opted to be on medical therapy with anti-HTN medications and spironolactone. Case 3 has been scheduled for BAVS. Currently, all have controlled blood pressure and normalized potassium levels with calcium channel blocker and betablocker, and spironolactone administration, respectively. Conclusion and Recommendation: The three (3) reported cases suggest that cyclical or periodic secretion of aldosterone in patients with primary hyperaldosteronism may not be uncommon. With high index of suspicion, intravenous saline infusion test must be performed so as not to miss the diagnosis. Presentation: Saturday, July 12, 2025