title: Effect of weight loss after bariatric surgery on kidney function in a multiethnic Asian population.
abstract: BACKGROUND
  Current literature reports improvement in kidney function in obese patients after bariatric surgery in non-Asian centers. It is unclear how kidney function is affected by postoperative body composition changes in obese Asian patients.
  
  
  OBJECTIVE
  To evaluate kidney function and its relationship to body composition in a multiethnic Asian population after bariatric surgery.
  
  
  METHODS
  This study was performed in a university hospital.
  
  
  METHODS
  Data of 68 obese patients who were followed for 1 year after surgery were retrieved from our university hospital clinical care database. Body composition was obtained by bioimpedance analysis. Kidney function was calculated as glomerular filtration rate (GFR) using the following formulas: (1) Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) (estimated GFR [eGFR], mL/min/1.73 m(2)); (2) absolute GFR (aGFR, mL/min); and (3) lean weight-adjusted Cockcroft-Gault creatinine clearance (CG-LBW, mL/min). Patients were further examined by 2 subgroups: eGFR<90 and>90 mL/min/1.73 m(2).
  
  
  RESULTS
  One year after surgery, body mass index (BMI) declined from 41.9±5.7 to 29.6±4.2 kg/m(2) (P<.001), body surface area (BSA) decreased from 2.15±0.23 to 1.86±0.18 m(2) (P<.001), and fat mass (FM) reduced from 45.8±9.4 to 25.6±10.5 kg (P<.001). There were significant differences in percentage excess weight loss (%EWL) among Chinese, Malays, Indians, and other ethnicities. Similar results were found with percentage fat mass loss (%FML). Changes in aGFR were associated with reductions in FM (P = .010), BSA (P = .049), and %EWL (P<.001). In the eGFR>90 subgroup, eGFR decreased from 143±22 to 122±19 mL/min/1.73 m(2). Conversely, in the eGFR<90 subgroup, eGFR had a trend of improvement from 69 to 79 mL/min/1.73 m(2).
  
  
  CONCLUSIONS
  Changes in eGFR after bariatric surgery in the obese Asian patient are strongly associated with reduction in FM, BSA, and %EWL. More work is required to investigate if certain ethnicities have better postoperative renal profiles.
authors.affiliation: Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Clara Lee Ying
authors.initials: CLY
authors.lastname: Ngoh
authors.affiliation: Department of General Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Jimmy Bok Yan
authors.initials: JBY
authors.lastname: So
authors.affiliation: Department of Urology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Ho Yee
authors.initials: HY
authors.lastname: Tiong
authors.affiliation: Department of General Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Asim
authors.initials: A
authors.lastname: Shabbir
authors.affiliation: Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. Electronic address: mdctbw@nus.edu.sg.
authors.forename: Boon Wee
authors.initials: BW
authors.lastname: Teo
mesh_terms: D000273:Adipose Tissue / Q000502:physiology; D000328:Adult; D001208:Asia / Q000208:ethnology; D050110:Bariatric Surgery / Q000379:methods*; D001823:Body Composition / Q000502:physiology; D003404:Creatinine / Q000378:metabolism; D005260:Female; D005743:Gastrectomy / Q000379:methods; D005919:Glomerular Filtration Rate / Q000502:physiology; D006801:Humans; D008297:Male; D009765:Obesity / Q000208:ethnology / Q000503:physiopathology* / Q000601:surgery; D011182:Postoperative Care; D011183:Postoperative Complications / Q000208:ethnology / Q000503:physiopathology; D051436:Renal Insufficiency, Chronic / Q000208:ethnology / Q000503:physiopathology*; D015431:Weight Loss / Q000208:ethnology* / Q000502:physiology
chemical_list: D003404:Creatinine
keywords: Bariatric surgery; Body composition; Ethnicity; Fat mass; Glomerular filtration rate; Hyperfiltration