Allon N Friedman1, Sara K Quinney2, Margaret Inman3, Samer G Mattar4, Zak Shihabi5, Sharon Moe6. 1. Department of Medicine, Indiana University School of Medicine, Indianapolis, IN. Electronic address: allfried@iu.edu. 2. Department of Medicine, Indiana University School of Medicine, Indianapolis, IN; Department of Obstetrics and Gynecology, Indiana University School of Medicine, Indianapolis, IN. 3. Meridian Surgical Group, Inc, Carmel, IN. 4. Department of Surgery, Indiana University School of Medicine, Indianapolis, IN. 5. Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, NC. 6. Department of Medicine, Indiana University School of Medicine, Indianapolis, IN; Department of Medicine, Roudebush Veterans Affairs Medical Center, Indianapolis, IN.
Abstract
BACKGROUND: Obesity-associated elevations in glomerular filtration rate (GFR) are common and may play a role in the development of kidney disease, so identifying the underlying mechanism is important. We therefore studied whether reductions in dietary protein intake, which is known to modulate GFR, explain why GFR decreases after bariatric surgery-induced weight loss. STUDY DESIGN: Cohort study with participants as their own controls. SETTING & PARTICIPANTS: 8 severely obese patients with normal kidney function were recruited from bariatric surgery centers in Indianapolis, IN. All participants were placed on a fixed-protein (50-g/d) diet for 1 week before and after a minimum of a 20-kg weight loss by bariatric surgery and were followed up closely by dieticians for adherence. PREDICTOR: Ad lib versus low-protein diet before versus after bariatric surgery. OUTCOME: Measured GFR, using repeated-measures analysis, was used to estimate the independent effects of diet and surgery. MEASUREMENT: GFR was measured using plasma iohexol clearance. RESULTS: A median of 32.9 (range, 19.5-54.4)kg was lost between the first presurgery visit and first postsurgery visit. Dietetic evaluations and urinary urea excretion confirmed that patients generally adhered to the study diet. GFRs on an ad lib diet were significantly higher before compared to after surgery (GFR medians were 144 (range, 114-178) and 107 (range, 85-147) mL/min, respectively; P=0.01). Although bariatric surgery (-26mL/min; P=0.005) and dietary sodium intake (+7.5mL/min per 100mg of dietary sodium; P=0.001) both influenced GFR, consuming a low-protein diet did not (P=0.7). LIMITATIONS: Small sample size; mostly white women; possible lack of generalizability. CONCLUSIONS: The decrease in GFR observed after bariatric surgery is explained at least in part by the effects of surgery and/or dietary sodium intake, but not by low dietary protein consumption.
BACKGROUND:Obesity-associated elevations in glomerular filtration rate (GFR) are common and may play a role in the development of kidney disease, so identifying the underlying mechanism is important. We therefore studied whether reductions in dietary protein intake, which is known to modulate GFR, explain why GFR decreases after bariatric surgery-induced weight loss. STUDY DESIGN: Cohort study with participants as their own controls. SETTING & PARTICIPANTS: 8 severely obesepatients with normal kidney function were recruited from bariatric surgery centers in Indianapolis, IN. All participants were placed on a fixed-protein (50-g/d) diet for 1 week before and after a minimum of a 20-kg weight loss by bariatric surgery and were followed up closely by dieticians for adherence. PREDICTOR: Ad lib versus low-protein diet before versus after bariatric surgery. OUTCOME: Measured GFR, using repeated-measures analysis, was used to estimate the independent effects of diet and surgery. MEASUREMENT: GFR was measured using plasma iohexol clearance. RESULTS: A median of 32.9 (range, 19.5-54.4)kg was lost between the first presurgery visit and first postsurgery visit. Dietetic evaluations and urinary urea excretion confirmed that patients generally adhered to the study diet. GFRs on an ad lib diet were significantly higher before compared to after surgery (GFR medians were 144 (range, 114-178) and 107 (range, 85-147) mL/min, respectively; P=0.01). Although bariatric surgery (-26mL/min; P=0.005) and dietary sodium intake (+7.5mL/min per 100mg of dietary sodium; P=0.001) both influenced GFR, consuming a low-protein diet did not (P=0.7). LIMITATIONS: Small sample size; mostly white women; possible lack of generalizability. CONCLUSIONS: The decrease in GFR observed after bariatric surgery is explained at least in part by the effects of surgery and/or dietary sodium intake, but not by low dietary protein consumption.
Authors: Chi-yuan Hsu; Charles E McCulloch; Carlos Iribarren; Jeanne Darbinian; Alan S Go Journal: Ann Intern Med Date: 2006-01-03 Impact factor: 25.391
Authors: Allon N Friedman; Matthew Strother; Sara K Quinney; Stephen Hall; Susan M Perkins; Edward J Brizendine; Margaret Inman; Gerardo Gomez; Zak Shihabi; Sharon Moe; Lang Li Journal: Nephron Clin Pract Date: 2010-07-02
Authors: Allon N Friedman; Zhangsheng Yu; Beth E Juliar; James T Nguyen; Matthew Strother; Sara K Quinney; Lang Li; Margaret Inman; Gerardo Gomez; Zak Shihabi; Sharon Moe Journal: Kidney Int Date: 2010-07-21 Impact factor: 10.612
Authors: Allon N Friedman; Sharon Moe; William F Fadel; Margaret Inman; Samer G Mattar; Zak Shihabi; Sara K Quinney Journal: Am J Nephrol Date: 2013-12-19 Impact factor: 3.754
Authors: Alex R Chang; Yuan Chen; Christopher Still; G Craig Wood; H Lester Kirchner; Meredith Lewis; Holly Kramer; James E Hartle; David Carey; Lawrence J Appel; Morgan E Grams Journal: Kidney Int Date: 2016-05-12 Impact factor: 10.612
Authors: Kamyar Kalantar-Zadeh; Connie M Rhee; Jason Chou; S Foad Ahmadi; Jongha Park; Joline Lt Chen; Alpesh N Amin Journal: Kidney Int Rep Date: 2017-02-01