Changes in plasma aldosterone level after weight loss by bariatric surgery in morbidly obese patients.

Background: Overactivation of renin-aldosterone-angiotensin system (RAS) is part of the pathogenesis of obesity-associated hypertension. Evidences have shown that weight loss can result in reduction in blood pressure and RAS. This study was aim to investigate changes of plasma aldosterone concentration (PAC) after bariatric surgery.

Methods: A prospective study was done in 14 morbidly obese patients undergoing bariatric surgery. Patients who were taking medications that can interfere with PAC and renin levels were excluded. Collection of blood samples were done at baseline and at 3 and 6-month post-bariatric surgery.

Results: Four out of 14 patients had hypertension at baseline. Mean body mass index (BMI) was 56.7 ± 13.5 kg/m. PAC were significantly decreased at 3-and 6-month post-bariatric surgery from 14.3 ± 8.0 to 7.5 ± 5.5 [reduction of 36% from baseline (P < 0.01)] and 8.0 ± 6.6 ng/dl [reduction of 32% from baseline (P < 0.05)] respectively. The reduction of PAC at 3-month post-surgery was correlated with the reduction of body weight (r = 0.46, P < 0.05), waist circumference (r = 0.73, P < 0.05) and percent of body fat (r = 0.58, P < 0.05).

Conclusions: Maximal reduction of PAC in obese patients underwent bariatric surgery occurred during the first 3 months after bariatric surgery. The reduction of PAC was associated with the reduction of body weight, waist circumference and percent of body fat suggesting the link between RAS and obesity-mediated hypertension.