Extracellular fluid volume: A suitable indexation variable to assess impact of bariatric surgery on glomerular filtration rate in patients with chronic kidney disease.

Caroline Grangeon-Chapon,Coralie Cruzel,Audrey Laurain,Guillaume A Favre,Antonio Iannelli,Vincent L M Esnault,Petter Bjornstad

doi:10.1371/journal.pone.0256234

Abstract

BackgroundBariatric surgery (BS) might be a nephroprotective treatment in obese patients with chronic kidney disease (CKD), and the non-linear relation between body surface area (BSA) and extracellular fluid volume (ECFV) in obese people raises the question of the most relevant way to scale glomerular filtration rate (GFR) for assessing renal function changes after BS.MethodsWe screened 1774 BS candidates and analysed 10 consecutive participants with CKD stage 3. True GFR (mGFR), measured by the renal clearance of 51Cr-ethylenediaminetetraacetic acid (EDTA), was scaled either to BSA (mGFRBSA) or to ECFV measured by 51Cr-EDTA distribution volume (mGFRECFV) before and one year after BS.ResultsThe 10 candidates for BS had a mean body mass index of 43.3 ± 3.6 kg/m2 and a mean GFR of 48 ± 8 mL/min/1.73 m2. Six participants had a sleeve gastrectomy and four had a Roux-en-Y gastric bypass. One year after BS, ECFV decreased (23.2 ± 6.2 to 17.9 ± 4.3 L, p = 0.001), absolute mGFR was not significantly modified (74 ± 23 versus 68 ±19 mL/min), mGFRBSA did not change significantly (53 ± 18 versus 56 ± 17 mL/min/1.73 m2) whereas mGFRECFV significantly increased (42 ± 13 versus 50 ± 14 mL/min/12.9 L, p = 0.037). The relation between mGFRECFV and mGFRBSA was different from the identity line before (p = 0.014) but not after BS (p = 0.09).ConclusionThere is a difference between mGFRBSA and mGFRECFV following BS and the latter might better reflect the adequacy between renal function and corpulence.

Highlights

In the United States, 7.4 million people with chronic kidney disease (CKD) are deemed to be severely or morbidly obese [1], and about 13,000 of them were waitlisted for kidney transplantation between 1995 and 2006 [2]
The relation between mGFRECFV and mGFRBSA was different from the identity line before (p = 0.014) but not after Bariatric surgery (BS) (p = 0.09)
There is a difference between mGFRBSA and mGFRECFV following BS and the latter might better reflect the adequacy between renal function and corpulence

Summary

Introduction

In the United States, 7.4 million people with chronic kidney disease (CKD) are deemed to be severely or morbidly obese [1], and about 13,000 of them were waitlisted for kidney transplantation between 1995 and 2006 [2]. Only one study analysed mGFR changes after BS using the renal clearance of 125I-iothalamate in a cohort of 13 individuals with CKD stage 3 or 4. Absolute mGFR (mL/min) remained unchanged, suggesting the presence of a poor functional renal reserve [7]; mGFR scaled to body surface area (mGFRBSA, mL/min/1.73 m2) increased following weight loss [8]. Bariatric surgery (BS) might be a nephroprotective treatment in obese patients with chronic kidney disease (CKD), and the non-linear relation between body surface area (BSA) and extracellular fluid volume (ECFV) in obese people raises the question of the most relevant way to scale glomerular filtration rate (GFR) for assessing renal function changes after BS

Objectives

Methods

Results