Table 1.

The 3 cardinal features that define primary aldosteronism

1. Suppression of baseline renin secretion

Primary aldosteronism is a state of extracellular fluid volume expansion (specifically expansion of the effective arterial blood volume) that results in suppression of renin secretion and consequently decreased generation of angiotensin II.

2. Inability to stimulate renin secretion normally

The degree of renin suppression by volume expansion due to excess mineralocorticoid activity can be quantified by an inadequate rise in renin in response to common physiologic stimuli, including upright posture, sodium/volume contraction with diuresis or dietary sodium restriction, or the effect of an angiotensin-converting enzyme inhibitor. Patients with primary aldosteronism have a blunted rise in renin to these stimuli.

3. Inappropriate and nonsuppressible aldosterone production

Aldosterone production in primary aldosteronism is independent of renin and is relatively nonsuppressible despite volume expansion, inhibition of angiotensin II, and hypokalemia.