Aldosterone is Aberrantly Regulated by Various Stimuli in a High Proportion of Patients with Primary Aldosteronism

Abstract

Context: In primary aldosteronism (PA), aldosterone secretion is relatively independent of the renin-angiotensin system, but can be regulated by several other stimuli.

Objective: To evaluate aldosterone response to several stimuli in a series of patients with PA secondary either to bilateral adrenal hyperplasia (BAH) or unilateral aldosterone-producing adenoma (APA).

Design and setting: Prospective cohort study conducted in a university teaching hospital research center.

Patients: Forty-three patients with confirmed PA and subtyped by adrenal vein sampling (n = 39) were studied, including 11 with BAH, 28 with APA, and 4 with undefined etiology. We also studied 4 other patients with aldosterone and cortisol cosecretion.

Interventions: We systematically explored aberrant regulation of aldosterone using an in vivo protocol that included the following stimulation tests performed over 3 days under dexamethasone suppression: upright posture, mixed meal, adrenocorticotropin (ACTH) 1-24, gonadotropin-releasing hormone (GnRH), vasopressin, and serotonin R4 agonist.

Main outcome measures: Positive response was defined as >50% renin or ACTH-independent increase in plasma aldosterone/cortisol concentration following the various stimulation tests.

Results: Renin-independent aldosterone secretion increased in response to several aberrant stimuli (upright posture, GnRH) in up to 83% of patients with APA or BAH in whom ACTH 1-24 and HT4R agonists also produced aldosterone oversecretion in all patients. The mean significant aberrant responses per patient was similar in BAH (4.6) and in APA (4.0).

Conclusions: Aldosterone secretion in PA is relatively autonomous from the renin-angiotensin system, but is highly regulated by several other stimuli, which contributes to the large variability of aldosterone levels in PA patients.

Keywords: G-protein coupled receptor; aberrant regulation; aldosterone; cortisol cosecretion; primary aldosteronism.