This is a prospective study (with a target recruitment of 200 participants) designed to evaluate the performance characteristics of the seated saline infusion test and the ultra low-dose ACTH stimulation test for the diagnosis of primary aldosteronism, using disease-specific treatment response as a reference gold standard. Subjects consenting to study participation will undergo a standardized seated saline infusion test, followed by an ultra low-dose ACTH stimulation test. All participants also receive adrenal vein sampling. Individuals who have unilateral disease and desire surgery will receive adrenalectomy (as part of routine care) and the remaining subjects will receive medical treatment with a mineralocorticoid receptor antagonist. Response to targeted treatment will be considered the reference gold standard for the establishing the diagnosis of primary aldosteronism.
