UCSF

The effects of body mass index on the diagnostic accuracy of primary aldosteronism (PA) are inconsistent and yet important considering the high prevalence and frequent co-occurrence of obesity and hypertension. The current study included 59 adult patients who underwent a stepwise evaluation for PA, using aldosterone to renin ratio for case detection and plasma aldosterone concentration after saline suppression test and/or 24-hour urinary aldosterone after oral sodium loading for case confirmation. Body mass index had a quadratic (U-shaped) correlation with plasma aldosterone concentration, plasma renin activity, aldosterone to renin ratio, and plasma aldosterone concentration after saline suppression test. Among patients with a body mass index ≥30 kg/m² , the aldosterone to renin ratio yielded lower case detection accuracy of PA. We conclude that obesity results in a nonlinear correlation with plasma aldosterone concentration, plasma renin activity, and aldosterone to renin ratio, which affects the accuracy of case detection for PA. Patients with a body mass index ≥30 kg/m² are less accurately identified as having PA when saline suppression and/or oral salt loading tests are used for case confirmation.