title: Determinants of glomerular filtration rate following bariatric surgery in individuals with severe, otherwise uncomplicated, obesity: an observational, prospective study.
abstract: OBJECTIVE
  Obesity-induced nephropathy is an established clinical entity arising from a "maladaptive" response to lipid accumulation at the nephron level. Bariatric surgery positively affects renal function, reducing or increasing glomerular filtration rate (GFR) in subjects with hyperfiltration and renal impairment, respectively. The effect of this surgery in patients with normal estimated GFR (eGFR) is less clear.
  
  
  METHODS
  A complete clinical and biochemical assessment of 135 severely obese, otherwise healthy subjects, was obtained before Roux-en-Y gastric bypass (RYGB). All subjects underwent an OGTT with plasma glucose and insulin determinations. Follow-up data were recorded at 6, 12, 24 and 48 months after intervention.
  
  
  RESULTS
  Baseline eGFR was 98.2 ± 13.6 ml/min/1.73 m2; hyperfiltration (>120 ml/min/1.73 m2) was present in 7% of the cohort. No eGFR variation over the follow-up emerged, except at the last visit (-3.6 ± 1.4 ml/min/1.73 m2at month 48, p = 0.01 vs baseline). In the univariate analysis, the renal performance at 48 months was inversely related to baseline eGFR (r = -0.17, p = 0.04) and plasma triglycerides (r = -0.04, p = 0.05). Fasting and OGTT-derived variables did not impact eGFR. By multiple regression analysis, eGFR time course was independently predicted only by baseline eGFR (p = 0.03). Interestingly, patients having a baseline eGFR >100 ml/min/1.73 m2(median value) showed, after 48 months, an average loss of -8.3 ± 2.2 ml/min/1.73 m2, while those with eGFR <100 exhibited a slight increase (+1.8 ± 2.3 ml/min/1.73 m2, p < 0.01).
  
  
  CONCLUSIONS
  Long-term data confirm the safety of RYGB on renal function. Interestingly, a subtle hyperfiltration, i.e., occurring in high-normal range of eGFR, is attenuated by surgical procedure. Lastly, high serum triglycerides may track an unfavorable renal outcome.
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Seghieri
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors.forename: Edoardo
authors.initials: E
authors.lastname: Vitolo
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors.forename: Livia
authors.initials: L
authors.lastname: Giannini
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Santini
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Rossi
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Salvati
authors.affiliation: Department of Surgical, Medical, Molecular and Critical Area Pathology, University of Pisa, 56126, Pisa, Italy. anna.solini@med.unipi.it.
authors.forename: Anna
authors.identifier: http://orcid.org/0000-0002-7855-8253
authors.initials: A
authors.lastname: Solini
mesh_terms: D000328:Adult; D050110:Bariatric Surgery / Q000534:rehabilitation; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000503:physiopathology* / Q000601:surgery*; D011446:Prospective Studies; D055815:Young Adult
keywords: Bariatric surgery; Estimated glomerular filtration rate (eGFR); Hyperfiltration; Obesity-induced nephropathy; Renal function outcome