Prospective Phenotyping of Autonomous Aldosterone Secretion

Primary aldosteronism is a disorder wherein aldosterone is secreted by the adrenal gland(s) independent of its physiologic regulators and cannot be appropriately suppressed with sodium/volume loading. Primary aldosteronism is a common cause of hypertension and has a relatively high prevalence. This is important since the excessive mineralocorticoid receptor activation in primary aldosteronism contributes to adverse cardiovascular and renal outcomes and death. For these reasons, it is critical that autonomous aldosteronism be detected early in its course since appropriate treatment interventions may prevent cardiovascular disease. In addition to severe and overt primary aldosteronism in hypertension, human studies have shown that milder forms of primary aldosteronism can exist even among normotensive individuals. Detailed physiologic studies have shown that normotensive individuals with a phenotype of autonomous aldosterone secretion have greater cardiometabolic risk factors, impaired renal-vascular function, and a higher risk for developing incident hypertension. Further, older age is associated with greater autonomous aldosterone secretion, suggesting that autonomous aldosterone secretion may progress over time. A better understanding of the prevalence and progression of this type of "subclinical" autonomous aldosterone secretion may inform our understanding of the pathogenesis of hypertension and cardiometabolic diseases. This protocol is designed to be a prospective longitudinal study that will carefully characterize the degree of autonomous aldosterone secretion among high-risk normotensive individuals and follow them longitudinally with repeated phenotyping study visits to assess the progression and severity of autonomous aldosterone secretion over time and its relevance to cardiovascular health. Phenotyping visits will include measurements of the renin-angiotensin-aldosterone system under controlled posture and variable sodium intakes and repeated assessments of blood pressure. This prospective cohort study will provide insights into normal and abnormal aldosterone physiology over time and how it may contribute to time- or age-dependent hypertension and cardiometabolic risk.