Body mass index predicts aldosterone production in normotensive adults on a high-salt diet

Context: The mechanisms underlying obesity- mediated cardiovascular disease are not fully understood. Aldosterone and insulin resistance both are associated with obesity and cardiovascular disease. Objectives: The objectives of this study were to test the hypotheses that aldosterone production is elevated and associated with insulin resistance in overweight adults on a high- sodium diet. Participants/ Interventions: Healthy normotensive adults were categorized as lean body mass index ( BMI) less than 25 kg/ m(2) ( n = 63) or overweight BMI 25 kg/ m(2) or greater ( n = 57). After 7 d of a high- sodium diet, participants fasted overnight and remained supine throughout hemodynamic and laboratory assessments and angiotensin II ( AngII) stimulation. Results: The overweight group, compared with the lean group, had higher 24- h urinary aldosterone ( 9.0 +/- 0.8 vs. 6.6 +/- 0.5 mu g per 24 h; P = 0.003) and higher AngII- stimulated serum aldosterone ( 11.4 +/- 1.0 vs. 9.0 +/- 0.6 ng/ dl; P = 0.04). There were no differences in 24- h urinary cortisol or sodium or supine measurements of plasma renin activity, serum aldosterone, or serum potassium. The homeostasis model assessment of insulin resistance was predicted by urinary aldosterone excretion ( r = 0.32, P = 0.03) and serum aldosterone response to AngII stimulation ( r = 0.28, P = 0.02) independent of age and BMI. Conclusion: Urinary aldosterone excretion and AngII- stimulated aldosterone are increased in overweight, compared with lean, normotensive adults. The correlation of these measures of aldosterone production with insulin resistance suggests a potential role for aldosterone in the pathophysiology of obesity- mediated insulin resistance.