The Spectrum of Dysregulated Aldosterone Production: An International Human Physiology Study

Abstract

Context: Primary aldosteronism is a form of low-renin hypertension characterized by dysregulated aldosterone production.

Objective: To investigate the contributions of renin-independent aldosteronism, and ACTH-mediated aldosteronism, in individuals with a low-renin phenotype representing the entire continuum of blood pressure.‏.

Design/participants: Human physiology study of 348 participants with a low-renin phenotype with severe and/or resistant hypertension, hypertension with hypokalemia, elevated blood pressure and stage I/II hypertension, and normal blood pressure.

Setting: 4 international centers.‏.

Interventions/main outcome measures: Saline suppression test (SST) to quantify the magnitude of renin-independent aldosteronism; dexamethasone suppression and ACTH-stimulation tests to quantify the magnitude of ACTH-mediated aldosteronism; adrenal venous sampling to determine lateralization.

Results: There was a continuum of non-suppressible and renin-independent aldosterone production following SST that paralleled the magnitude of the blood pressure continuum and transcended conventional diagnostic thresholds. In parallel, there was a full continuum of ACTH-mediated aldosteronism wherein post-SST aldosterone levels were strongly correlated with ACTH-stimulated aldosterone production (r = 0.75, P < 0.0001) and non-suppressible aldosterone production post-dexamethasone (r = 0.40, P < 0.0001). Beyond participants who met criteria for primary aldosteronism (post-SST aldosterone of ≥10 ng/dL or ≥277 pmol/L), the continuum of non-suppressible and renin-independent aldosterone production persisted below this diagnostic threshold, wherein 15% still had lateralizing aldosteronism amenable to surgical adrenalectomy, and the remainder were treated with mineralocorticoid receptor antagonists.

Conclusions: In the context of a low-renin phenotype, there is a continuum of dysregulated aldosterone production that is prominently influenced by ACTH. A large proportion of individuals with low-renin have dysregulated aldosterone production and may benefit from aldosterone-directed therapy.

Keywords: ACTH; aldosterone; hypertension; low-renin hypertension; primary aldosteronism.