Mild primary aldosteronism (PA) followed by overt PA are possibly the most common forms of low renin hypertension: a single-center retrospective study.

Low renin hypertension (LRH) is a common condition in hypertensive patients, and mainly includes primary aldosteronism (PA) and low renin essential hypertension. To investigate the distributions and clinical manifestations of the main LRH forms, we reviewed 1267 hypertensive patients who underwent assessment for plasma renin activity (PRA) and plasma aldosterone concentration (PAC) by standardized protocols in our specialized center. LRH was defined as PRA < 1.0 ng/mL/h. A saline infusion test (SIT) was performed when LRH patients showed positive screening results for PA. The main LRH forms were defined as follows: post-SIT PAC > 10 ng/dL as 'overt PA', post-SIT PAC 5-10 ng/dL as 'mild PA', and post-SIT PAC < 5 ng/dL or negative screening results as 'non-PA'. Overall, 760 patients were defined as LRH, with 160 classified as overt PA, 268 as mild PA, and 332 as non-PA. The total proportion of PA amounted to 56.3% with 21.0% overt PA and 35.3% mild PA. Compared with the mild PA, patients with overt PA had higher systolic and diastolic blood pressures, lower serum potassium, higher urine potassium excretion, more frequent incidence of stage 3 hypertension, hypokalemia, diabetes mellitus, and classical unilateral adenoma on computerized tomography (P < 0.05). PA including overt and mild forms is indeed a major form of LRH. Clinical manifestations in mild PA are less severe than those in overt PA. Nevertheless, mild PA is more prevalent than overt PA in LRH and should be recognized.