Body mass index predicts plasma aldosterone concentrations in overweight-obese primary hypertensive patients.

CONTEXT

Body mass index (BMI) shows a direct correlation with plasma aldosterone concentration (PAC) and urinary aldosterone excretion in normotensive individuals; whether the same applies to hypertensive patients is unknown.

OBJECTIVE

Our objective was to determine if BMI predicts PAC and the PAC/plasma renin activity ratio [aldosterone renin ratio (ARR)] in hypertensive patients, and if this affects the identification of primary aldosteronism (PA).

DESIGN

This was a prospective evaluation of consecutive hypertensive patients referred nationwide to specialized hypertension centers.

MAIN OUTCOME MEASURES

Sitting PAC, plasma renin activity, and the ARR, baseline and after 50 mg captopril orally with concomitant assessment of parameters, including BMI and daily sodium intake, were calculated.

RESULTS

Complete biochemical data and a definite diagnosis were obtained in 1125 consecutive patients. Of them 999 had primary (essential) hypertension (PH) and 126 (11.2%) PA caused by an aldosterone-producing adenoma in 54 (4.8%). BMI independently predicted PAC (beta = 0.153; P < 0.0001) in PH, particularly in the overweight-obese, but not in the PA group. Covariance analysis and formal comparison of the raw, and the BMI-, sex-, and sodium intake-adjusted ARR with receiver operator characteristic curves, showed no significant improvement for the discrimination of aldosterone-producing adenoma from PH patients with covariate-adjusted ARR.

CONCLUSIONS

BMI correlated with PAC independent of age, sex, and sodium intake in PH, but not in PA patients. This association of BMI is particularly evident in overweight-obese PH patients, and suggests a pathophysiological link between visceral adiposity and aldosterone secretion. However, it does not impact on the diagnostic accuracy of the ARR for discriminating PA from PH patients.