Obesity Surgery

, Volume 29, Issue 1, pp 197–206 | Cite as

Analyzing the Impact of Bariatric Surgery in Kidney Function: a 2-Year Observational Study

  • Daniela S. C. MagalhãesEmail author
  • Jorge M. P. Pedro
  • Pedro E. B. Souteiro
  • João Sérgio Neves
  • Sofia Castro-Oliveira
  • Rita Bettencourt-Silva
  • Maria Manuel Costa
  • Ana Varela
  • Joana Queirós
  • Paula Freitas
  • Davide Carvalho
Original Contributions



Obesity is an independent risk factor for chronic kidney disease (CKD). Our aims were: (1) to evaluate the impact of bariatric surgery (BS) on kidney function, (2) clarify the factors determining postoperative evolution of glomerular filtration rate (ΔGFR) and urinary albumin-to-creatinine ratio (ΔUACR), and (3) access the occurrence of oxalate-mediated renal complications.


We investigated a cohort of 1448 obese patients who underwent BS. Those with baseline-estimated GFR (eGFR0) < 30 mL/min or without information about the 2-year post-surgical eGFR (eGFR2) were excluded.


A total of 725 patients were included. At baseline, 38(5.2%) had hyperfiltration with eGFR0 ≥ 125 mL/min/1.73m2 (G0), 492 (67.9%) had eGFR0 90–124 mL/min/1.73m2 (G1), 178 (24.6%) had eGFR0 60–89 mL/min/1.73m2 (G2), and 17 (2.3%) had eGFR0 < 60 mL/min/1.73m2 (G3). ΔGFR significantly increased in 96.6% (ΔGFR = 23.8 (IQR 15.9–29.8)) and 82.4% (ΔGFR = 18.6 (IQR 3.6–44.0)) of the subjects with G2 and G3 CKD, respectively (p < 0.001). The variables independently associated with ΔGFR were baseline body mass index (BMI) (positively), high blood pressure (HBP) (negatively), and fasting plasma glucose (FPG) (negatively), as well as FPG variation (positively). An overall prevalence of high UACR (≥ 30 mg/g−1) of 17.9% was found, with 81.5% of these subjects presenting A2(30–300 mg/g−1) and 18.5% A3(> 300 mg/g−1) UACR. UACR significantly decreased after BS (p < 0.001). Significant predictors of ΔUACR were BMI, systolic blood pressure, and HbA1c. Urinary excretion of calcium oxalate crystals was found in 77(11.1%) patients, with only 1 presenting oxalate-mediated renal complications.


ΔGFR seems to be influenced by the initial kidney function, as it decreases in subjects with hyperfiltration but tends to increase in those with kidney dysfunction. These results suggest that BS is associated with improvement of kidney outcomes, without a significant increase in renal complications.


Albuminuria Bariatric surgery Glomerular filtration rate Renal function 



Diabetes mellitus


High blood pressure


Chronic kidney disease


Urinary albumin excretion


Bariatric surgery


Estimated glomerular filtration rate


Roux-en-Y gastric bypass


Baseline-estimated glomerular filtration rate


2-Year post-surgery estimated glomerular filtration rate


Body mass index


Waist circumference


Hip circumference


Systolic blood pressure


Diastolic blood pressure


White blood cells count


C-reactive protein


Fasting plasma glucose


Urinary albumin-to-creatinine ratio


Isotope dilution mass spectrometry


Chronic kidney disease epidemiology collaboration formula


Kidney disease improving global outcomes


Glomerular filtration rate variation


Urinary albumin-to-creatinine ratio


High-power field


Variance inflation factor


Adjustable gastric band


Vertical gastrectomy


Excess weight loss


High-density lipoprotein cholesterol




Total cholesterol


Low-density lipoprotein cholesterol


Authors’ Contributions

All authors participated in the collection of data. DM interpreted the data and wrote the manuscript. All authors read and approved the final manuscript.


This research did not receive any specific grant from any funding agency in the public, commercial, or not-for-profit sector.

Compliance with Ethical Standards

Conflict of Interest

The authors declare that they have no conflict of interest.

Ethical Approval

All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed Consent

Informed consent was obtained from all individual participants included in the study.


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  • Daniela S. C. Magalhães
    • 1
    • 2
    • 3
    Email author
  • Jorge M. P. Pedro
    • 1
    • 2
    • 3
  • Pedro E. B. Souteiro
    • 1
    • 2
    • 3
  • João Sérgio Neves
    • 1
    • 2
    • 3
  • Sofia Castro-Oliveira
    • 1
    • 2
    • 3
  • Rita Bettencourt-Silva
    • 1
    • 2
    • 3
  • Maria Manuel Costa
    • 1
    • 2
    • 3
  • Ana Varela
    • 1
    • 2
    • 3
    • 4
  • Joana Queirós
    • 1
  • Paula Freitas
    • 1
    • 2
    • 3
    • 4
  • Davide Carvalho
    • 1
    • 2
    • 3
  1. 1.Endocrinology, Diabetes and Metabolism DepartmentCentro Hospitalar São JoãoPortoPortugal
  2. 2.Faculty of MedicineUniversity of PortoPortoPortugal
  3. 3.Instituto de Investigação e Inovação em SaúdeUniversity of PortoPortoPortugal
  4. 4.Multidisciplinary Group for Surgical Management of ObesityCentro Hospitalar de São JoãoPortoPortugal

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