Effects of Obesity Surgery on Renal Function

Increasing risk of impaired renal function as a result of obesity is well known. Early data has postulated that weight loss might improve kidney function, but the evidence is rather limited due to the difficulties in measuring glomerular filtration rate(GFR) after weight loss. Cystatin C, GFR measurement using Cockcroft-Gault (CCG) and Modification of Diet in Renal Disease (MDRD) equations, have all yield conflicting results after weight loss surgery.

The study aim to assess:

1. use of 51Cr-EDTA Clearance as the methodological gold standard in evaluating changes in renal function before and after weight loss surgery. 2. the reliability of using MDRD, CCG and Cystatin C in measuring GFR after weight loss surgery 3. the differences in alterations in renal function dependent on the surgical procedures( gastric bypass, gastric band, sleeve gastrectomy). 4. the use of urine albumin/creatinine ratio in detecting alterations in microalbuminuria.

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Key information

Conditions

Impaired Renal Function Female Urogenital Diseases Female Urogenital Diseases and Pregnancy Complications Kidney Diseases Male Urogenital Diseases Renal Insufficiency Urogenital Diseases Urologic Diseases

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Charing Cross Hospital

London, W6 8RF, United Kingdom

About this study

This is a prospective study on obese human subjects undergoing bariatric surgery. Forty-five patients due to undergo gastric bypass (n=15), gastric banding (n=15), and gastric sleeve surgery (n=15) will be recruited.

Subjects will be screened prior to entry into the study with full history, examination, routine bloods (FBC, U+E, liver function tests, and glucose).

Blood samples and 24h urine specimens are taken at four time points: preoperatively as well 6 weeks, 6 and 12 months postoperatively.
The following methods of GFR assessment will be executed the same time point: measurement of serum creatinine concentration, calculation of the abbreviated and extended MDRD formulae, CCG, creatinine clearance, serum Cystatin C concentration and the 51Chromium-EDTA clearance.

Inclusion criteria

Patients with a BMI of >35kg/m2 approved for obesity surgery based on the NICE criteria.
Patients with a GFR <60 mL/min/1.73

Exclusion criteria

Allergy to chromium

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Patients with a BMI of >35kg/m2 approved for obesity surgery based on the NICE criteria.
Patients with a GFR <60 mL/min/1.73 m2

Exclusion criteria

Allergy to chromium

Treatment and study plan

Primary outcomes

Changes in Glomerular Renal Function After Weight Loss Surgery as Measured by 51Cr-EDTA Clearance

Time frame: 12 months

The outcome measure is reported as the number of participants who achieved a change in the glomerular renal function after weight loss surgery as measured by 51Cr-EDTA Clearance.

51Cr-EDTA GFR was ascertained using bolus injection of 1.46-2.66 MBq 51Cr-EDTA, with between 6 and 8 venous blood samples were collected at approximately 15, 30, 60, 90, 120, 180, 240, and 300 min to assess 51Cr-EDTA clearance. 51Cr-EDTA GFR was calculated using the Bi-exponential Fitting Method described in the British Nuclear Medicine Society guidelines. The prepared standard and patient samples were counted for 15 and 60 mins respectively using a Wallac 1470 Wizard Gamma Counter (Perkin Elmer Inc., Waltham, Massachusetts, USA). The measured GFR was scaled to BSA in order to maintain uniformity in comparison to reported eGFR.

Sponsors and collaborators

Lead sponsor

Imperial College London

Other

Registry information

Important dates

Study start: 2011
Primary completion: 2016
Study completion: 2016
First posted: Jan 10, 2012
Registry last updated: Nov 19, 2020

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Published trials that share one or more normalized conditions with this study.

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