The objective was to estimate the prevalence of plasma aldosterone concentration:plasma renin activity ratio >30 ng/dL:ng/mL/h in patients with resistant hypertension and to describe the computed tomography findings of adrenal glands in those with elevated ratios. In a cross-sectional design, 492 patients were enrolled. All patients with plasma aldosterone concentration:plasma renin activity ratio ≥30 ng/dL:ng/mL/h (n=77) underwent abdominal computed tomography. Patients with an adrenal image of possible aldosterone-producing adenoma underwent a saline-loading test. The prevalence of elevated plasma aldosterone concentration:plasma renin activity ratio was 15.7% (95% confidence interval, 12.6–19.2). Twelve patients showed adrenal abnormalities on computed tomography. The level of renin was low in 50% of the sample. Results indicate a low prevalence of aldosterone-producing adenoma. Our evidence points out the importance of confirming the hypothesis that essential hypertension, low-renin hypertension, and idiopathic hyperaldosteronism could be the same disease, but at different neurohormonal stages, and aldosterone-producing adenoma may be yet another disease.