This study consisting of 221 black and 276 white subjects with previously diagnosed essential hypertension was conducted between 1996 and 2000. Antihypertensive drugs were withdrawn for at least 4 weeks; PAC and PRA were measured while subjects were supine and then seated after 30 minutes of ambulation. The seated measurements were repeated after 4 weeks of oral diuretic therapy with hydrochlorothiazide (25 mg/d). In patients with previously diagnosed essential hypertension, calculation of the aldosterone-renin ratio does not provide a renin-independent measure of circulating aldosterone that is suitable for determining whether PAC is elevated relative to PRA. Because elevation of the aldosterone-renin ratio is predominantly an indicator of low PRA, its perceived value in screening for primary aldosteronism most likely derives from additional diagnostic tests being done in patients with low-renin hypertension.
