Gold-Standard Test Shows High Rates of Primary Aldosteronism

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Primary aldosteronism is more common than previously recognized, and prevalence rises with severity of hypertension, reports a study in the Annals of Internal Medicine.

The cross-sectional study included participants from studies at four US medical centers: 298 with normotension, 115 with stage 1 hypertension, 203 with stage 2 hypertension, and 408 with resistant hypertension. All underwent an oral sodium suppression test, regarded as a gold-standard confirmatory test for primary aldosteronism. The study definition of “biochemically overt” primary aldosteronism was a urinary aldosterone level greater than 12 µg/24 h.

In all four blood pressure categories, participants with higher renin-independent aldosterone production had higher blood pressure, increased potassium excretion, and lower serum potassium. Mean adjusted urinary aldosterone level was 6.5 µg/24 h in the normotensive group, 7.3 µg/24 h in participants with stage 1 hypertension, 9.5 µg/24 h in those with stage 2 hypertension, and 14.6 µg/24 h in those with resistant hypertension.

Adjusted prevalence of biochemically overt primary aldosteronism was 11.3% in the normotensive group, 15.7% in participants with stage 1 hypertension, 15.7% in those with stage 2 hypertension, and 22.0% in those with resistant hypertension. The aldosterone–renin ratio had low sensitivity and negative predictive value for biochemically overt primary aldosteronism.

Patients with primary aldosteronism have nonsuppressible, renin-independent aldosterone production, associated with hypertension and adverse cardiovascular outcomes. The aldosterone–renin ratio is the currently recommended screening test for primary aldosteronism.

The new study, using the oral sodium suppression test, finds a high prevalence of unrecognized, biochemically overt primary aldosteronism. The findings “show the existence of a pathologic continuum of nonsuppressible renin-independent aldosterone production that parallels the severity of hypertension,” the researchers write. They believe that primary aldosteronism should not be regarded as a “rare and categorical disease,” but rather as a common contributor to hypertension across the full range of severity [Brown JM, et al. The unrecognized prevalence of primary aldosteronism: a cross-sectional study. Ann Intern Med 2020; 173:10–20].