ObesityOBBYSSNCT02218112
Impact of Weight Loss After a Bypass Surgery on Renal Hemodynamic Under Stress Conditions
An observational study of Obesity and Bariatric Surgery, run by Centre Hospitalier Universitaire Vaudois at 1 site in Switzerland.
Trial summary
The sympathetic nervous (SNS) and the renin angiotensin aldosterone system (RAS) have a direct impact on renal hemodynamic, hormonal secretion and vasoactive peptide. Many mechanisms including the SNS, RAS and renal sodium handling could explain the pathogenesis of hypertension in obese patients. Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- Obesity, Bariatric Surgery, Blood Pressure
- What is being tested?
- bariatric surgery (gastric bypass)
- Type of treatment
- Surgery or procedure
- How many people
- 36 participants
- Where
- 1 siteSwitzerland
- Study dates
- Jun 2014to 31 Jul 2017
- How long will I take part?
- 1 Year
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Patient will briefly be informed about the study during their follow-up at the obesity consultation (Medical Universitary Polyclinic) and the they will be recruited at the Nephrology center in CHUV (Lausanne).
Who may be able to join
- BMI >35 Kg/m2
- Understanding and signing the informed consent
- Estimated glomerular filtration rate >60 ml/min/1.73 m2
Who cannot join
- Acute disease
- Asthma or history of asthma
- Patient participating in another clinical trial 30 days before the beginning of the study
- Blood donation (450ml) 2 months before the beginning of the study
- Chronic medication which influence renal function (NSAIDS, Others)
- Allergy
Show all 18Show fewer
- Documented renal arterial stenosis
- History of symptomatic orthostatic hypotension
- Kidney transplantation
- Kidney malformation / polycystic kidney disease
- Impaired judgement
- Liver failure with ascitis
- Hip circumference at the upper anterior iliac spine > 130cm
- Waist circumference >180cm and weighing > 220kg
- Contraindication/Allergy to furosemide, PAH or Inulin
- Contraindication to MRI if the patient is going to undergo BOLD-MRI
- Postprandial glycemia > 11.0 mmol/L in diabetic patients
- Blood pressure > 180/110 assessed by 24 hour blood pressure measurement
Trial locations and contacts
1 site in 1 country.
Switzerland1 site
Centre Hospitalier Universitaire Vaudois
Lausanne, Canton of Vaud, 1004
About this study
Official title: Effect of Weight Loss Induced by a Bypass Surgery on Renal Salt Excretion, Renal Hemodynamic and on Neurohormonal Responses During an Induced Orthostatic Stress in Obese Patients
The sympathetic nervous (SNS) and the renin angiotensin aldosterone system (RAS) have a direct impact on renal hemodynamic, hormonal secretion and vasoactive peptide. Many mechanisms including the SNS, RAS and renal sodium handling could explain the pathogenesis of hypertension in obese patients. Lifestyle changes and bariatric surgery induce weight loss, which is associated with blood pressure lowering in obese patients. A diminution in the renal sympathetic stimulation and RAS activation could explain this effect.
The AIM of this study is to show that weight loss induced by bypass surgery in obese patients affects renal salt excretion under " low body negative pressure (LBNP)" conditions .
Read more
Secondary objectives are to investigate the impact of weight loss on renal hemodynamic (glomerular filtration rate (GFR), renal plasma flow) and neurohormonal responses under " low body negative pressure conditions ". We will also analyse renal blood oxygenation with Blood Oxygenation dependant IRM (BOLD-IRM) technique before and after weight loss.
The population of this study will consist in two groups including 36 patients. The first one will include 24 obese patients that are going to undergo a bariatric surgery. The second one will include 12 obese patients without any weight loss associated surgery.
Both group will undergo 3 investigation days. Each patient will have to undergo a screening visit that will provide dietary advice to ensure a standardized salt intake (120-180 mmol/day) for the duration of the study. The first investigation will define baseline, the second and third day of investigation will take place after 3 month and 12 month after bariatric surgery for surgical patients or after baseline for patients without surgery. One to two weeks before phase 1 and 3 patients will perform a BOLD-MRI. The surgery group will undergo bariatric surgery between the first investigation phase (baseline) and the second. An ambulatory blood pressure and 24-hour urine collection will precede each investigation day. An investigation day consists in renal hemodynamics, neurohormonal and natriuretic response measurements before, during and after 60 min of LBNP at -30mbar . The duration of the study per subject is going to take 12 months.
- Conditions
- Obesity, Bariatric Surgery, Blood Pressure
- Being tested
- bariatric surgery (gastric bypass)
- Keywords
- Blood pressure, Obesity, Glomerular filtration rate, Renal Sodium handling
- Medical subject headings
- Obesity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
bariatric surgery (gastric bypass)Procedure or surgery
| Study group | Role | What they receive |
|---|---|---|
| OB - Bariatric surgery (gastric bypass) | Obese patients who will undergo a bariatric surgery (gastric bypass) Receives: Procedure: bariatric surgery (gastric bypass) | |
| OB- Control group | Obese patients who will not undergo surgery - Control group |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in sodium excretion
Change in sodium excretion during LBNP conditions
Measured: up to one year
Secondary outcomes (1)
Blood pressure, renal hemodynamic and neurohormonal response
- 24 hour blood pressure measurement
- Inulin clearance for GFR measurement
- Renal plasma flow measured with p-aminohippuric acid (PAH) administration
- Renin plasmatic activity
- Aldosterone (plasma)
- Leptin (plasma)
- Adiponectin (plasma)
- Plasmatic and urinary electrolytes
- Plasmatic and urinary lithium
Measured: up to one year
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted15 Aug 2014 (estimated)
- Study startJun 2014
- Primary completion31 Jul 2017
- Study completion31 Jul 2017
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for ObesityStudies of the same condition, open and under way.
- More trials run by Centre Hospitalier Universitaire VaudoisThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 36 participants (actual)
- Target duration
- 1 Year
Sponsor and investigators
- Lead sponsor
- Centre Hospitalier Universitaire Vaudois
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, PD Dr. Grégoire Wuerzner, Centre Hospitalier Universitaire Vaudois
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT02218112
- Sponsor's protocol ID
- SNF_ 32003B_149903
- Acronym
- OBBYSS
- Status last verified
- Mar 2018
- First submitted
- 14 Aug 2014
- Last updated
- 16 Mar 2018
- Results posted
- No
- Data monitoring committee
- No
Publications
Zahnd J, Vakilzadeh N, Schwotzer N, Hendriks-Balk M, Mantziari S, Sauser J, Maillard M, Grouzmann E, Favre L, Wuerzner G. Weight loss following gastric bypass increases aldosterone reactivity to orthostatic stress in patients with obesity. Blood Press. 2025 Dec;34(1):2555452. doi: 10.1080/08037051.2025.2555452. Epub 2025 Sep 16.
PubMed 40892437Berney M, Vakilzadeh N, Maillard M, Faouzi M, Grouzmann E, Bonny O, Favre L, Wuerzner G. Bariatric Surgery Induces a Differential Effect on Plasma Aldosterone in Comparison to Dietary Advice Alone. Front Endocrinol (Lausanne). 2021 Oct 5;12:745045. doi: 10.3389/fendo.2021.745045. eCollection 2021.
PubMed 34675881
Study at a glance
From the registry record, last updated by the sponsor on 16 Mar 2018. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effect of Weight Loss Induced by a Bypass Surgery on Renal Salt Excretion, Renal Hemodynamic and on Neurohormonal Responses During an Induced Orthostatic Stress in Obese Patients
- ClinicalTrials.gov ID
- NCT02218112
- Acronym / sponsor ID
- OBBYSS / SNF_ 32003B_149903
- Conditions
- Obesity, Bariatric Surgery, Blood Pressure
- Keywords
- Blood pressure, Obesity, Glomerular filtration rate, Renal Sodium handling
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 36 participants (actual)
- Lead sponsor
- Centre Hospitalier Universitaire VaudoisUniversity, hospital or other
- Study start
- Jun 2014 (actual)
- Primary completion
- 31 Jul 2017 (actual)
- Study completion
- 31 Jul 2017 (actual)
- First posted
- 15 Aug 2014 (estimated)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The sympathetic nervous (SNS) and the renin angiotensin aldosterone system (RAS) have a direct impact on renal hemodynamic, hormonal secretion and vasoactive peptide. Many mechanisms including the SNS, RAS and renal sodium handling could explain the pathogenesis of hypertension in obese patients. Lifestyle changes and bariatric surgery induce weight loss, which is associated with blood pressure lowering in obese patients. A diminution in the renal sympathetic stimulation and RAS activation could explain this effect.
The AIM of this study is to show that weight loss induced by bypass surgery in obese patients affects renal salt excretion under " low body negative pressure (LBNP)" conditions .
Secondary objectives are to investigate the impact of weight loss on renal hemodynamic (glomerular filtration rate (GFR), renal plasma flow) and neurohormonal responses under " low body negative pressure conditions ". We will also analyse renal blood oxygenation with Blood Oxygenation dependant IRM (BOLD-IRM) technique before and after weight loss.
The population of this study will consist in two groups including 36 patients. The first one will include 24 obese patients that are going to undergo a bariatric surgery. The second one will include 12 obese patients without any weight loss associated surgery.
Both group will undergo 3 investigation days. Each patient will have to undergo a screening visit that will provide dietary advice to ensure a standardized salt intake (120-180 mmol/day) for the duration of the study. The first investigation will define baseline, the second and third day of investigation will take place after 3 month and 12 month after bariatric surgery for surgical patients or after baseline for patients without surgery. One to two weeks before phase 1 and 3 patients will perform a BOLD-MRI. The surgery group will undergo bariatric surgery between the first investigation phase (baseline) and the second. An ambulatory blood pressure and 24-hour urine collection will precede each investigation day. An investigation day consists in renal hemodynamics, neurohormonal and natriuretic response measurements before, during and after 60 min of LBNP at -30mbar . The duration of the study per subject is going to take 12 months.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Target follow-up
- 1 Year
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| OB - Bariatric surgery (gastric bypass) | – | Procedure: bariatric surgery (gastric bypass)Obese patients who will undergo a bariatric surgery (gastric bypass) |
| OB- Control group | – | –Obese patients who will not undergo surgery - Control group |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Patient will briefly be informed about the study during their follow-up at the obesity consultation (Medical Universitary Polyclinic) and the they will be recruited at the Nephrology center in CHUV (Lausanne).
Key inclusion criteria (3 listed)
- BMI >35 Kg/m2
- Understanding and signing the informed consent
- Estimated glomerular filtration rate >60 ml/min/1.73 m2
Key exclusion criteria (18 listed)
- Acute disease
- Asthma or history of asthma
- Patient participating in another clinical trial 30 days before the beginning of the study
- Blood donation (450ml) 2 months before the beginning of the study
- Chronic medication which influence renal function (NSAIDS, Others)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| bariatric surgery (gastric bypass) | Procedure or surgery | OB - Bariatric surgery (gastric bypass) |
Primary outcome
Change in sodium excretion
Time frame: up to one year
Change in sodium excretion during LBNP conditions
1 secondary outcome
Blood pressure, renal hemodynamic and neurohormonal response
Time frame: up to one year
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 16 Mar 2018.
- Derived from this study: PubMed 40892437Zahnd J, Vakilzadeh N, Schwotzer N, Hendriks-Balk M, Mantziari S, Sauser J, Maillard M, Grouzmann E, Favre L, Wuerzner G. Weight loss following gastric bypass increases aldosterone reactivity to orthostatic stress in patients with obesity. Blood Press. 2025 Dec;34(1):2555452. doi: 10.1080/08037051.2025.2555452. Epub 2025 Sep 16.
- Derived from this study: PubMed 34675881Berney M, Vakilzadeh N, Maillard M, Faouzi M, Grouzmann E, Bonny O, Favre L, Wuerzner G. Bariatric Surgery Induces a Differential Effect on Plasma Aldosterone in Comparison to Dietary Advice Alone. Front Endocrinol (Lausanne). 2021 Oct 5;12:745045. doi: 10.3389/fendo.2021.745045. eCollection 2021.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Obesity and Bariatric Surgery, run by Centre Hospitalier Universitaire Vaudois at 1 site in Switzerland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 18 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 16 Mar 2018. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in sodium excretion (time frame: up to one year). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT02218112, which also lists 2 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 16 Mar 2018.