Work

Weight loss following gastric bypass increases aldosterone reactivity to orthostatic stress in patients with obesity

Year: 2025

Type: article

Abstract: Background Weight loss after gastric bypass is associated with blood pressure reduction. However, the precise role of the sympathetic nervous system and renin-angiotensin-aldosterone system in this reduction remains unclear. We investigated the effect of RYGB-induced weight loss on the hemodynamic, hormonal, and renal responses to an orthostatic stress induced by lower body negative pressure (LBNP).Methods We conducted a monocentric study comparing response to LBNP (-30 mbar) in two groups of obese participants: the first group underwent RYGB surgery (RYGB group) and the second group received lifestyle counselling (control group). We studied urinary sodium excretion, hemodynamic and hormonal responses before, during and one hour after orthostatic stress induced by LBNP at three timelines: one month before planned RYGB (intervention group), and 3 and 12 months after the intervention.Results Thirty-seven adult participants were enrolled: 25 patients (72% women, age: 42.1 ± 10.5 years old, BMI 43.0 ± 5.1kg/m2) in the RYGB group and 12 in control group (58% women, age: 44.8 ± 13.6 years old, BMI 43.3 ± 5.3kg/m2). At 12 months, mean weight decreased from 126.3 ± 23.2kg to 116 ± 20.7kg in the control group and from 120.9 ± 19.4kg to 78.6 ± 14.0kg in the RYGB group (p-value < 0.01 between groups). During LBNP, the reduction in urinary sodium excretion (-1.98 mmol/h; CI95%: -3.72 to -0.30, p-value = 0.02) and the increase in plasma aldosterone concentration (+9.94pg/ml, CI95%: 0.317 to 19.569, p-value = 0.043) were more pronounced in the RYGB group.Conclusion Our study suggests that weight loss induced by RYGB increases aldosterone responsiveness to orthostatic stress and enhances the sodium tubular response during orthostatic stress.ClinicalTrials.gov ID NCT02218112

Source: Blood Pressure

DOI: 10.1080/08037051.2025.2555452