Kidney Week

Abstract: SA-PO832

Change in Glomerular Filtration Rate After Bariatric Surgery Varies by Baseline Kidney Function

Session Information

• Health Maintenance, Nutrition, Metabolism - II
  November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Health Maintenance, Nutrition, and Metabolism

• 1300 Health Maintenance, Nutrition, and Metabolism

Authors

• Chang, Alex R., Geisinger Medical Center, Danville, Pennsylvania, United States

Alex R. Chang,

• Inker, Lesley, Tufts Medical Center, Boston, Massachusetts, United States

Lesley Inker,

• Levey, Andrew S., Tufts Medical Center, Boston, Massachusetts, United States

Andrew S. Levey,

• Coresh, Josef, Welch Center for Prevention, Epidemiology & Clinical Research, Baltimore, Maryland, United States

Josef Coresh,

• Grams, Morgan, Johns Hopkins University, Baltimore, Maryland, United States

Morgan Grams,

Background

It is unclear whether GFR decreases after bariatric surgery in individuals with lower baseline GFR who may lack renal functional reserve.

Methods

GFR was measured by plasma iohexol clearance in 27 adults at multiple research visits before and after bariatric surgery (twice pre-surgery, ~6 and 12 months post-surgery). We examined whether changes in GFR after bariatric surgery varied by pre-surgery GFR using generalized estimating equations, clustered by individuals.

Results

Pre-surgery, mean values of body mass index (BMI) and body surface area (BSA) were 49.4 kg/m²and 2.42 m². Mean unindexed and indexed GFR were 117.3 ml/min (range 57.4 to 206.0) and 84.1 ml/min/1.73m² (range 44.3 to 138.0), respectively. Six months after surgery, BMI decreased by 13.9 kg/m² (95% CI: -15.9, -11.8) and BSA decreased by 0.30 m² (95% CI: -0.34, -0.27). Post-surgery changes in GFR varied by pre-surgery GFR (p<0.001 for interaction). Those in the middle and upper tertiles of pre-surgery GFR had declines in unindexed GFR at 6 months post-surgery (upper tertile: -22.6 ml/min, -36.0, -9.2; middle tertile: -12.74, -23.1, -2.4). By contrast, individuals in the lowest tertile (GFR <100 ml/min) did not have a decline in unindexed GFR (8.9 ml/min, -2.2, 20.0). Indexed GFR was unchanged 6 months after surgery in the upper 2 tertiles whereas indexed GFR increased by 15.3 ml/min/1.73m²(95% CI: 6.4, 24.3) in the lowest tertile. Overall, albuminuria tended to decrease (-41%, 95% CI: -67%, 4%). Findings were consistent in additional analyses accounting for regression to the mean, using GFR measurements from the other visits.

Conclusion

GFR did not decrease after bariatric surgery in severely obese individuals with GFR < 100 ml/min. This may reflect less capacity for physiologic changes in GFR, though we lack the ability to discern physiologic from pathologic decline in GFR.

Changes in GFR after Bariatric Surgery, by Baseline Tertile of GFR

Funding

• NIDDK Support