Renin Phenotypes Characterize Vascular Disease, Autonomous Aldosteronism, and Mineralocorticoid Receptor Activity.

Context: Mild cases of autonomous aldosterone secretion may go unrecognized using current diagnostic criteria for primary aldosteronism (PA). Objective: To investigate whether the inability to stimulate renin serves as a biomarker for unrecognized autonomous aldosterone secretion and mineralocorticoid receptor (MR) activation. Participants: Six hundred sixty-three normotensive and mildly hypertensive participants, who were confirmed to not have PA using current guideline criteria and were on no antihypertensive medications. Design: Participants had their maximally stimulated plasma renin activity (PRA) measured while standing upright after sodium restriction. Tertiles of maximally stimulated PRA were hypothesized to reflect the degree of MR activation: lowest PRA tertile = "Inappropriate/Excess MR Activity;" middle PRA tertile = "Intermediate MR Activity;"; and highest PRA tertile = "Physiologic MR Activity." All participants underwent detailed biochemical and vascular characterizations under conditions of liberalized sodium intake, and associations with stimulated PRA phenotypes were performed.
Results: Participants with lower stimulated PRA had greater autonomous aldosterone secretion [higher aldosterone-to-renin ratio (P = 0.002), higher urine aldosterone excretion rate (P = 0.003), higher systolic blood pressure (P = 0.004), and lower renal plasma flow (P = 0.04)] and a nonsignificant trend toward lower serum potassium and higher urine potassium excretion, which became significant after stratification by hypertension status. Conclusions: In participants without clinical PA, the inability to stimulate renin was associated with greater autonomous aldosterone secretion, impaired vascular function, and suggestive trends in potassium handling that indicate an extensive spectrum of unrecognized MR activation.