Table 2: Studies which support the concept of primary aldosteronism as a continuum.

Rather than employ categorical thresholds for primary aldosteronism, these studies demonstrated a severity-spectrum of renin-independent aldosterone production that was associated with higher blood pressure or a higher risk for developing incident elevations in blood pressure or hypertension.

Methods	Findings	Population	Reference
Measurement of PRA during sodium restriction	Maximally stimulated PRA inversely correlated with blood pressure	42 normotensive patients	39
Measurement of PAC	Higher aldosterone levels associated with higher blood pressure and more incident HTN	1688 normotensive patients in Framingham cohort	41
Measurement of ARR	Higher ARR associated with higher blood pressure and more incident HTN	3326 normotensive patients in Framingham cohort	42
Double-blind, placebo-controlled, crossover trial comparing efficacy of spironolactone, doxazosin, bisoprolol, and placebo in patients with hypertension despite 3 drugs	Spironolactone most effective fourth anti-hypertensive agent in resistant hypertension, especially in the context of lower renin and higher aldosterone levels	285 participants with resistant hypertension in the UK (PATHWAY-2 and substudy)	37, 38
Measurement of aldosterone and renin	In context of a suppressed renin, higher aldosterone levels associated with a higher incidence of hypertension	850 normotensive patients from the Multi-Ethnic Study of Atherosclerosis cohort	43
Measurement of PRA during sodium restriction	Lower PRA associated with higher blood pressure, lower potassium, and greater autonomous aldosterone production	663 normotensive and mildly hypertensive participants in the U.S.	40