Comment on: GFR in the early postoperative period in bariatric surgery

Letter to the Editor

Dear Editor,
We read with great interest the study by Karahisar Şirali et al. published in the Annals of Clinical and Analytical Medicine, which investigated the effects of postoperative changes in vitamin and iron parameters on glomerular filtration rate (GFR) in patients undergoing sleeve gastrectomy.¹ The authors demonstrated that vitamin and iron fluctuations did not negatively affect short-term renal function, and that the transient GFR decline at one month largely recovered by the third postoperative month. We congratulate the authors for addressing this clinically relevant topic; however, we would like to draw attention to an important dimension not discussed in the study: the emerging role of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) as both a weight-loss modality and a direct renal protective agent in obese patients.
Obesity is a well-established risk factor for chronic kidney disease (CKD) through mechanisms including glomerular hyperfiltration, inflammation, and metabolic dysregulation. While bariatric surgery effectively addresses these pathways, GLP-1 RAs have emerged as a pharmacological alternative with comparable cardiometabolic benefits and, importantly, pleiotropic renal protective effects that extend beyond weight reduction.² At the hemodynamic level, GLP-1 RAs reduce intraglomerular pressure via natriuresis and afferent arteriolar vasodilation. Additionally, they attenuate renal inflammation through NF-κB inhibition, suppress TGF-β1-mediated tubulointerstitial fibrosis, and reduce oxidative stress in podocytes and proximal tubular cells — mechanisms largely independent of systemic glycemic improvement.³
These mechanistic benefits are now supported by robust clinical evidence. The landmark FLOW trial demonstrated that semaglutide 1.0 mg weekly reduced the composite renal endpoint — including a ≥50% sustained eGFR decline, kidney failure, and renal death — by 24% in patients with type 2 diabetes and CKD.⁴ Importantly, these benefits were observed across all albuminuria and CKD severity subgroups, suggesting broad applicability.
In the context of the study by Karahisar Şirali et al., many obese patients undergoing bariatric surgery share overlapping risk profiles — insulin resistance, hypertension, and early CKD — with those who would benefit from GLP-1 RA therapy. As GLP-1 RAs become increasingly integrated into obesity management, future studies examining their impact on perioperative and long-term renal outcomes in bariatric surgery candidates would be of significant clinical value. Incorporating GLP-1 RAs into nephroprotective strategies for obese patients — whether as a surgical adjunct or alternative — warrants further investigation. Furthermore, unlike bariatric surgery, which is an irreversible intervention, GLP-1 RA therapy offers the advantage of reversibility: treatment can be discontinued in the event of adverse outcomes, providing greater flexibility in long-term management strategies for obese patients with early CKD.

Declarations

References

1. Karahisar Şirali S, Büberci R, Ocaklı S. GFR in the early postoperative period in bariatric surgery. Ann Clin Anal Med. 2026;17(5):433-438. doi:10.4328/acam.22848
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2. Bae JH. SGLT2 inhibitors and GLP-1 receptor agonists in diabetic kidney disease: evolving evidence and clinical application. Diabetes Metab J. 2025;49(3):386-402. doi:10.4093/dmj.2025.0220
   Article · PubMed · Google Scholar
3. Kawanami D, Takashi Y. GLP-1 receptor agonists in diabetic kidney disease: from clinical outcomes to mechanisms. Front Pharmacol. 2020;11:967. doi:10.3389/fphar.2020.00967
   Article · PubMed · Google Scholar
4. Perkovic V, Tuttle KR, Rossing P, et al. Effects of semaglutide on chronic kidney disease in patients with type 2 diabetes. N Engl J Med. 2024;391(2):109-121. doi:10.1056/nejmoa2403347
   Article · PubMed · Google Scholar

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