Observed frequency of primary aldosteronism among adults with low-grade hypertension in routine outpatient practice

Primary aldosteronism (PA) is a treatable but often missed cause of hypertension (HTN). Relying solely on resistant HTN or hypokalemia for screening overlooks many patients with mild disease. We aimed to determine the observed frequency of PA among routine outpatient adults with low grade HTN.

In this single centre observational study, we enrolled 300 consecutive adults (18-70 yrs) with low grade HTN (well controlled BP <140/90 mmHg and Grade 1 HTN <160/100 mmHg). We excluded secondary HTN, eGFR <45 mL/min/1.73 m², resistant HTN and diagnosed diabetes. Interfering antihypertensives were withdrawn. Morning fasting plasma aldosterone concentration (PAC) and direct renin concentration (DRC) were measured. Patients with aldosterone to renin ratio (ARR) >2.5 ng/dL per mU/L (with PAC >10 and DRC ≤8.2) underwent confirmatory saline suppression.

PA was confirmed in 24/300 (8.0%) patients. The mean ARR was significantly higher in PA cases than non PA (3.52 ± 1.1 vs 0.94 ± 0.9 ng/dL per mU/L; p<0.0001). PA patients had lower serum potassium (3.42 vs 4.13 mEq/L), higher fasting glucose (122.1 vs 104.2 mg/dL) and higher frequency of left ventricular hypertrophy, (LVH) (58.3% vs 20.2%), stroke (16.7% vs 1.8%), and obstructive sleep apnea (OSA) (20.9% vs 2.5%). Most PA cases were asymptomatic.

Among routine patients with low grade HTN, the observed frequency of PA was 8%, associated with significantly higher cardiometabolic burden despite similar blood pressure (BP). We strongly reinforce the existing recommendation that every hypertensive patient should be screened for PA at least once. In practical terms, we specifically urge clinicians to ensure this strategy includes routine patients with low grade HTN.