Measurement of glomerular filtration rate in patients undergoing obesity surgery.

BACKGROUND: Most studies on obesity surgery have measured renal function using the estimated GFR. However, due to the reduction of muscle mass, and therefore creatinine that accompanies weight loss, such measures can falsely suggest an improvement in renal function. To balance the risks of surgery versus any potential benefits on renal function, we need to be able to determine renal function using valid and reliable methodologies. In this pilot study we aimed to measure renal function in patients with CKD undergoing obesity surgery using the gold standard 51Cr-EDTA GFR clearance methodology which is independent of measures of muscle mass. METHODS: Nine consecutive obese patients with CKD underwent obesity surgery. Their renal function was assessed using 51Cr-EDTA GFR, cystatin C and serum creatinine as well as using eGFR equations including MDRD CKD Epi, Cockcroft Gault and CKD Epi cystatin before and 12 months after surgery. RESULTS: Renal function using the 51Cr-EDTA measured GFR did not change significantly after surgery. Similar results were obtained when Cystatin C, CKD Epi cystatin, CKD Epi cystatin creatinine and adjusted Cockcroft Gault Creatinine clearance methods were used. In contrast there were either trends or significant improvements in renal function measured using the MDRD and CKD Epi equations. CONCLUSIONS: In this pilot study using the gold standard 51Cr-EDTA method we found stabilisation in renal function after obesity surgery. Until further definitive data emerge it is critical to balance the risk and benefits of surgery, especially if renal function may not improve as often as previously suggested. TRIAL REGISTRATION: ClinicalTrials.gov NCT01507350 . Registered June 2011.

Impact of perioperative management of glycemia in severely obese diabetic patients undergoing gastric bypass surgery.

BACKGROUND: Roux-en-Y gastric bypass (RYGB) surgery is associated with rapid postsurgical improvement in glycemic control in patients with type 2 diabetes mellitus (T2 DM). However, there is little outcome-based evidence to guide the glycemic management of this patient group preoperatively. OBJECTIVES: We conducted 2 pilot studies randomizing patients to assess the impact of intensive glucose management pre- and post-RYGB on clinical outcomes after surgery. SETTING: University hospital. METHODS: In the GLUCOSURG-pre randomized controlled trial (RCT), 34 obese T2 DM patients with glycated hemoglobin (HbA1 c) ≥8.5% (69 mmol/mol) undergoing RYGB were randomly assigned to receive either glucose optimization or no optimization 3 months preoperatively. In the GLUCOSURG-post RCT, 35 obese T2 DM patients on insulin were randomly assigned to either intensive or conservative glucose management up to 2 weeks post- RYGB. HbA1c at 1 year post-RYGB was the primary outcome. RESULTS: In GLUCOSURG-pre, the HbA1 c at 1 year postsurgery was -3.0% (51.9 mmol/mol) in the optimized and -4.0% (45.4 mmol/mol) in the nonoptimized groups (P = .06). In GLUCOSURG-post, there were no significant differences in HbA1 c at 1 year postsurgery between the intensive and conservative groups [-2.4% (44.3 mmol/mol)] versus [-2.3% (44.3 mmol/mol), P = .73)]. CONCLUSIONS: Our pilot studies suggested that neither intensive management of glycemia in the 3 months pre- RYGB, nor the first 2 weeks post-RYGB resulted in better glycemic control one year after surgery. RYGB has substantial effects on glucose control, and additional intensive glucose-lowering interventions do not confer clinical benefits compared to conservative approaches.