The effects of bariatric surgery on cardiac function: a systematic review and meta-analysis

INTRODUCTION

Obesity is associated with alterations in cardiac structure and haemodynamics leading to cardiovascular mortality and morbidity. Culminating evidence suggests improvement of cardiac structure and function following bariatric surgery.

OBJECTIVE

To evaluate the effect of bariatric surgery on cardiac structure and function in patients before and after bariatric surgery.

METHODS

Systematic review and meta-analysis of studies reporting pre- and postoperative cardiac structure and function parameters on cardiac imaging in patients undergoing bariatric surgery.

RESULTS

Eighty studies of 3332 patients were included. Bariatric surgery is associated with a statistically significant improvement in cardiac geometry and function including a decrease of 12.2% (95% CI 0.096-0.149; p < 0.001) in left ventricular (LV) mass index, an increase of 0.155 (95% CI 0.106-0.205; p < 0.001) in E/A ratio, a decrease of 2.012 mm (95% CI 1.356-2.699; p < 0.001) in left atrial diameter, a decrease of 1.16 mm (95% CI 0.62-1.69; p < 0.001) in LV diastolic dimension, and an increase of 1.636% (95% CI 0.706-2.566; p < 0.001) in LV ejection fraction after surgery.

CONCLUSION

Bariatric surgery led to reverse remodelling and improvement in cardiac geometry and function driven by metabolic and haemodynamic factors.

Cardiac function, structural, and electrical remodeling by microgravity exposure

Space medicine is key to the human exploration of outer space and pushes the boundaries of science, technology, and medicine. Because of harsh environmental conditions related to microgravity and other factors and hazards in outer space, astronauts and spaceflight participants face unique health and medical challenges, including those related to the heart. In this review, we summarize the literature regarding the effects of spaceflight on cardiac structure and function. We also provide an in-depth review of the literature regarding the effects of microgravity on cardiac calcium handling. Our review can inform future mechanistic and therapeutic studies and is applicable to other physiological states similar to microgravity such as prolonged horizontal bed rest and immobilization.

The Impact of Bariatric Surgery on Cardiac Structure, and Systolic and Diastolic Function in Patients with Obesity: A Systematic Review and Meta-analysis

The purpose of this study was to provide pooled data from all studies on the impact of bariatric surgery on cardiac structure, and systolic and diastolic function evaluated by either echocardiography or cardiac magnetic resonance. PubMed, Web of Science, Embase, and Scopus databases were searched. Almost all of cardiac left-side structural indices improved significantly after bariatric surgery. However, right-side structural indices did not change significantly. Left ventricular ejection fraction and most of the diastolic function indices improved significantly after the bariatric surgery. The subgroup analysis showed that the left ventricular mass index decreased more in long-term follow-up (≥ 12 months). In addition, subgroup analysis of studies based on surgery type did not reveal any difference in outcomes between gastric bypass and sleeve gastrectomy groups.

Bariatric Surgery Improves Heart Geometry and Plasticity

BACKGROUND

Obesity is commonly associated with increased sympathetic tone, changes in heart geometry, and mortality. The aforementioned translates into a higher and potentially modifiable mortality risk for this specific population.

OBJECTIVES

The aim of the study was to analyze the extent of changes in the heart ventricular structure following rapid weight loss after bariatric surgery.

SETTING

Academic, university-affiliated hospital.

METHODS

We retrospectively reviewed all the patients that underwent bariatric surgery at our institution between 2010 and 2015. Data analyzed included demographics, BMI, and associated medical problems. Preoperative and postoperative echography readings were compared looking at the heart geometry, cardiac volumes, and wall thickness.

RESULTS

Fifty-one patients who had bariatric surgery and had echocardiography before and after the surgery were identified. There were 33 females (64.7%). The mean age was 63.4 ± 12.0 years with an average BMI of 40.3 ± 6.3. The mean follow-up was 1.2 years after the procedure. At 1 year follow-up 25 patients (49%, p = 0.01) showed normal left ventricular geometry. The left ventricular mass (229 ± 82.1 vs 193.2 ± 42.5, p<0.01) and the left ventricular end diastolic volume (129.4 ± 53 vs 96.4 ± 36.5, p = 0.01) showed a significant modification following the procedure. There was a significant improvement in the interventricular septal thickness (p = 0.01) and relative wall thickness (p < 0.01) following surgery.

CONCLUSION

The patients with obesity present a significant cardiac remodeling from concentric remodeling to normal geometry after bariatric surgery. The decrease in BMI has a direct effect on improvement of the left ventricular structure. Further studies must be carried out to define the damage of obesity to diastolic function.

A low serum iron level is a potential predictor of poor renal function in patients following laparoscopic sleeve gastrectomy: a retrospective study

This study aimed to assess the association of serum iron level (Iron) with the estimated glomerular filtration rate (eGFR) after bariatric surgery (BS). We reviewed 210 patients with mean age of 39.1 ± 10.6 years (body mass index, 41.4 ± 5.5 kg/m²) undergoing BS. The primary outcome was the relationship between Iron and eGFR at 12-month after surgery. Multiple linear regression analyses were performed using postoperative eGFR as dependent variables and using Iron and other variables (i.e., age) as independent variables. At 12-month follow-up, 94 patients were analyzed. BMI significantly decreased, whereas serum iron level significantly increased. Although the percentage of patients with eGFR of < 90 mL/min/1.73 m² increased during the study period, no significant difference was found in postoperative 12-month eGFR. No correlations were noted between Iron and eGFR at baseline and postoperative 1 and 6 months, whereas a significant relationship was observed between Iron and postoperative 12-month eGFR. Multiple linear regression analyses revealed that Iron and presence of diabetes were the independent predictors of postoperative 12-month eGFR. This pilot study showed a positive association of postoperative serum iron level with renal function in this patient population. Further large-scale trials are needed to confirm the findings.

Perioperative Risks of Sleeve Gastrectomy Versus Roux-en-Y Gastric Bypass Among Patients With Chronic Kidney Disease: A Review of the MBSAQIP Database

OBJECTIVE

To determine whether patients with CKD experience higher rates of perioperative complications after RYGB compared to sleeve gastrectomy.

SUMMARY OF BACKGROUND DATA

For obese CKD patients who qualify for bariatric surgery, sleeve gastrectomy is often preferred to RYGB based on perceptions of prohibitively-high perioperative risks surrounding RYGB. However, some patients with CKD are not candidates for sleeve gastrectomy and the incremental increased-risk from RYGB has never been rigorously tested in this population.

METHODS

CKD patients who underwent RYGB or sleeve gastrectomy between 2015 and 2017 were identified from the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program Participant Use File. RYGB patients were 1:1 propensity-score matched with sleeve gastrectomy patients based on preoperative factors that influence operative choice. Primary outcomes included 30-day readmissions, surgical complications, medical complications, and death. Secondary outcomes included the individual complications used to create the composite surgical/medical complications. Univariate logistic regression was used to compare outcomes. E-value statistic was used to test the strength of outcome point estimates against possible unmeasured confounding.

RESULTS

Demographics were similar between RYGB (n = 673) and sleeve gastrectomy (n = 673) cohorts. There were no statistically significant differences in primary outcomes. Among secondary outcomes, only acute kidney injury was statistically-significantly higher among RYGB patients (4.9% vs 2.7%, P = 0.035, E-value 1.27).

CONCLUSIONS

Among well-matched cohorts of RYGB and sleeve gastrectomy patients, incidence of primary outcomes were similar. Among secondary outcomes, only acute kidney injury was statistically-significantly higher among RYGB patients; however, the E-value for this difference was small and relatively weak confounder(s) could abrogate the statistical difference. The perception that RYGB has prohibitively-high perioperative risks among CKD patients is disputable and operative selection should be weighed on patient candidacy and anticipated long-term benefit.

Improvement of Renal Function After Bariatric Surgery: a Systematic Review and Meta-analysis

BACKGROUND/OBJECTIVE

The effect of bariatric surgery in renal function varies and the postoperative benefit time point remains unclear. We aim to assess the changes of renal function after bariatric surgery (BS) in different postoperative periods and subgroups.

METHODS

We searched the databases of PubMed and Cochrane from inception to December 14, 2020. Articles included in the study were drawn from all recipients of BS that provided assessments of renal function pre and post-surgery. Meta-analysis was performed to compare glomerular filtration rate (GFR), serum creatinine, albumin-to-creatinine ratio (ACR), and albuminuria before and after BS.

RESULTS

The study included 49 articles involving 8515 patients. Compared with pre-operative renal function, the overall analysis showed that bariatric surgery significantly reduced serum creatinine levels, ACR, and albuminuria. There was significant increase of GFR in the CKD subgroup, yet a noticeable decrease in the hyperfiltration subgroup. The most significant improvement in GFR was seen 6-12 months after BS, while ACR dropped most dramatically 12-24 months after BS.

CONCLUSIONS

Bariatric surgery can improve renal function in obese patients with kidney dysfunction, especially 1 year after surgery.

Comparative Effectiveness of Roux-en-Y Gastric Bypass vs. One Anastomosis Gastric Bypass on Kidney Function

PURPOSE

Obesity and its associated medical problems increase risk of kidney function decline while prior studies suggest that bariatric surgery may improve kidney outcomes. However, little is known about the comparative effectiveness of different types of bariatric surgery on kidney function. In this study, we compare the effects of laparoscopic one anastomosis gastric bypass (LOAGB) and laparoscopic Roux-en-Y gastric bypass (LRYGB) on kidney function one year after surgery.

MATERIALS AND METHODS

The patients' demographic, medical, and surgical data were prospectively collected and retrospectively reviewed. Type 2 diabetes mellitus, hypertension, and dyslipidemia, body mass index (BMI), and kidney function tests were obtained before and one year after surgery. Kidney function was evaluated by estimated glomerular filtration rate (eGFR) and spot urine albumin to creatinine ratio (ACR). Changes in eGFR and ACR were compared between LRYGB vs. LOAGB after adjustment for confounders (age, sex, remission of associated medical problems, preoperative BMI, and percentage of excess BMI loss) using ANCOVA model.

RESULTS

Both surgical techniques significantly decreased the post-surgery presence of diabetes, hypertension, and dyslipidemia (p < 0.001 for all paired comparisons). The eGFR level significantly increased and the ACR level significantly decreased in both groups (p < 0.001 for all paired comparisons before and after adjustment). However, eGFR and ACR mean differences between LRYGB and LOAGB were not significantly different after adjustment for confounding variables (p = 0.9 and 0.4, respectively).

CONCLUSION

Both LOAGB and LRYGB improved 1-year eGFR and ACR equally independently from weight loss and other confounders.

[Variations in echocardiography after bariatric surgery. Biliopancreatic diversion vs vertical gastrectomy]

Introduction

Introduction: obesity has become a worldwide health problem due to its relationship with cardiovascular morbimortality, thus bariatric surgery is considered as one of the main solutions for the correction of excess weight and, consequently, the improvement of its associated heart diseases. Objective: to compare vertical gastrectomy (VG) and biliopancreatic diversion (BPD) by observing echocardiographic characteristics both before and after surgery, as well as to evaluate surgical outcome in terms of the BAROS scale. Methods: results were collected from the echocardiographic testing requested for the preoperative study of patients who underwent surgery over the course of 24 months (from January 2014 to December 2015), as well as their anthropometric data. These were compared with postoperative parameters measured at 3 years after surgery. Results: finally, 26 patients were selected (13 VG and 13 BPD) with a mean age of 42 yrs. VG: initial BMI: 44.6 ± 7.1; final BMI: 31.8 ± 11.3 (p < 0.01); BPD: initial BMI: 48.1 ± 14.2; final BMI: 32.7 ± 10.4 (p < 0.01). Echocardiography: normal systolic function: 100% vs 92%; normal diastolic function: 88.5% vs 69.2%; no valvulopathy: 80% vs 69%; normal left atrium: 76.9% vs 73.1% (p > 0.05); HTA: 38.5% vs 19.2% (p < 0.05), preoperatively and postoperatively, respectively. Conclusions: no significant differences were found between the two groups studied with different techniques, although a slight deterioration in diastolic function was found in both groups. The comorbidities associated with obesity improved in both groups, and the surgery was scored as positive. The scant variation revealed by echocardiography prompts to reconsider its systematic preoperative use in these patients given the low cost-benefit ratio.

Renal hemodynamics and fatty acid uptake: effects of obesity and weight loss

Human studies of renal hemodynamics and metabolism in obesity are insufficient. We hypothesized that renal perfusion and renal free fatty acid (FFA) uptake are higher in subjects with morbid obesity compared with lean subjects and that they both decrease after bariatric surgery. Cortical and medullary hemodynamics and metabolism were measured in 23 morbidly obese women and 15 age- and sex-matched nonobese controls by PET scanning of [¹⁵O]-H₂O (perfusion) and 14(R,S)-[¹⁸F]fluoro-6-thia-heptadecanoate (FFA uptake). Kidney volume and radiodensity were measured by computed tomography, cardiac output by MRI. Obese subjects were re-studied 6 mo after bariatric surgery. Obese subjects had higher renal volume but lower radiodensity, suggesting accumulation of water and/or lipid. Both cardiac output and estimated glomerular filtration rate (eGFR) were increased by ~25% in the obese. Total renal blood flow was higher in the obese [885 (317) (expressed as median and interquartile range) vs. 749 (300) (expressed as means and SD) ml/min of controls, P = 0.049]. In both groups, regional blood perfusion was higher in the cortex than medulla; in either region, FFA uptake was ~50% higher in the obese as a consequence of higher circulating FFA levels. Following weight loss (26 ± 8 kg), total renal blood flow was reduced (P = 0.006). Renal volume, eGFR, cortical and medullary FFA uptake were decreased but not fully normalized. Obesity is associated with renal structural, hemodynamic, and metabolic changes. Six months after bariatric surgery, the hemodynamic changes are reversed and the structural changes are improved. On the contrary, renal FFA uptake remains increased, driven by high substrate availability.

The Effects of Bariatric Surgery on Renal Outcomes: a Systematic Review and Meta-analysis

BACKGROUND/OBJECTIVE

Although promising, data regarding the renal impact and safety of bariatric surgery (BS) are insufficient. We aimed at investigating the benefits and harms of BS for weight loss on kidney function.

METHODS

A systematic review and meta-analysis of observational studies reporting data about the impact of BS (any techniques) on serum/plasma creatinine, creatinine clearance, glomerular filtration rate (GFR), proteinuria, nephrolithiasis, and need for renal replacement therapy (RRT)) was performed. Obese adults (non-chronic kidney disease (CKD), CKD or transplanted patients) that underwent BS for weight loss were included. After searching MEDLINE (inception to August 2017), the Cochrane Library (Issue 10-12, October 2017), and the websiteclinicaltrials.gov (August 2017), data were extracted and summarized using a random-effects model.

RESULTS

The final analysis included 23 cohort studies, comprising 3015 participants. Compared with renal function before treatment, BS significantly decreased serum creatinine level (mean difference (MD), - 0.08 mg dl^-1; 95% confidence interval (CI), - 0.10 to - 0.06); p < 0.001) and proteinuria (MD, - 0.04 g 24 h^-1; 95% CI, - 0.06 to - 0.02; p < 0.001) in the overall group. GFR significantly improved 6 months or more after BS both in the hyperfiltration and CKD subgroups. Renal function also tended to improve in renal transplant patients. Data on nephrolithiasis and the need for RRT were scarce or not reported.

CONCLUSIONS

BS apparently has positive effects on kidney function and tends to normalize GFR across different categories of renal impairment (hyperfiltration and CKD patients).

Metabolic risk factors in nondiabetic adolescents with glomerular hyperfiltration

BACKGROUND

In adults, glomerular hyperfiltration is associated with abnormalities related to metabolic syndrome (MetS). We investigated if glomerular hyperfiltration was associated with metabolic abnormalities in US adolescents without diabetes.

METHODS

We analyzed data from the National Health and Nutrition Examination Survey, a nationally representative sample of US adolescents ages 12-17 years. Estimated glomerular filtration rate (eGFR) was determined using the bedside Schwartz equation; adolescents with hyperfiltration (eGFR >120 mL/min/1.73 m 2 ) were compared to those with normal eGFR (90-120 mL/min/1.73 m 2 ). We calculated mean levels of factors related to MetS, insulin resistance and diabetes risk, adjusting for age, race/ethnicity, sex, socioeconomic status, and BMI z -score.

RESULTS

Overall, 11.8% of US adolescents had hyperfiltration [95% confidence interval (CI) 10.6-13.0]. Hyperfiltration prevalence varied by race (20.2% in Hispanics versus 9.8% non-Hispanic whites and 7.4% non-Hispanic blacks; P< 0.001). Compared to those with normal eGFR, adolescents with hyperfiltration had higher adjusted mean levels of triglyceride (83 versus 77 mg/dL; P = 0.05), fasting insulin (15.1 versus 12.9; P< 0.001) and homeostatic model assessment of insulin resistance (3.52 versus 3.01; P = 0.001). These differences persisted after adjusting for BMI z- score. Adolescents with hyperfiltration had increased odds for hypertriglyceridemia [odds ratio 1.58 (95% CI 1.11-2.23)]. These relationships varied by racial/ethnic group.

CONCLUSIONS

Glomerular hyperfiltration is associated with hypertriglyceridemia and increased insulin resistance independent of BMI z- score in a nationally representative sample of US adolescents. Hispanic adolescents are more likely to have hyperfiltration than other racial/ethnic groups. These findings could have significance in evaluations of renal function and MetS in adolescents to identify related risks and target interventions.

Bariatric surgery is associated with renal function improvement

INTRODUCTION

Weight loss after bariatric surgery improves both blood pressure and glycemic control following surgery. The effect of bariatric surgery on renal function is not well characterized. In this study, we sought to quantify the change in renal function over time following surgery.

METHODS

We retrospectively reviewed all patients who underwent laparoscopic Roux-en-Y gastric bypass (LRYGB) or laparoscopic sleeve gastrectomy (LSG) between 2012 and 2014 at our institution. The glomerular filtration rate (GFR, mL/min) was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Body mass index (BMI, kg/m²) and percent weight loss (%WL) were calculated following the surgery.

RESULTS

A total of 149 patients who underwent bariatric surgery were included in this study: LRYGB (n = 86 and LSG (n = 63). In LRYGB group, baseline BMI (kg/m², ±SD) and GFR (mL/min, ±SD) were 48.5 ± 6.8 and 94.7 ± 23.8, respectively. In comparison, BMI and GFR were 49.1 ± 11.9 kg/m² and 93.1 ± 28.0 mL/min in the LSG group, respectively. Over the follow-up period (19.89 ± 10.93 months), the patients who underwent LRGYB lost a larger percentage of weight as compared to those in the LSG group (29.9 ± 11.7% vs 22.3 ± 10.7%; p = <0.0001). Overall, GFR improved in both LRYGB (101.0 ± 25.8 mL/min) and LSG groups (97.9 ± 25.8 mL/min) and was not significantly different between the two groups. Of patients with a GFR < 90 mL/min prior to weight loss surgery (n = 62), 42% had improvement of their GFR to > 90 mL/min postoperatively (p < 0.001). There was no relationship between weight loss percentage and GFR improvement (p = 0.8703).

CONCLUSIONS

Bariatric surgery was associated with improvement in postoperative renal function at almost two years following surgery but was not different for LRYGB versus LSG. The gain in GFR was independent of percentage of weight lost suggesting an alternate mechanism in the improvement of renal function other than weight loss alone.

Determinants of glomerular filtration rate following bariatric surgery in individuals with severe, otherwise uncomplicated, obesity: an observational, prospective study

AIMS

Obesity-induced nephropathy is an established clinical entity arising from a "maladaptive" response to lipid accumulation at the nephron level. Bariatric surgery positively affects renal function, reducing or increasing glomerular filtration rate (GFR) in subjects with hyperfiltration and renal impairment, respectively. The effect of this surgery in patients with normal estimated GFR (eGFR) is less clear.

METHODS

A complete clinical and biochemical assessment of 135 severely obese, otherwise healthy subjects, was obtained before Roux-en-Y gastric bypass (RYGB). All subjects underwent an OGTT with plasma glucose and insulin determinations. Follow-up data were recorded at 6, 12, 24 and 48 months after intervention.

RESULTS

Baseline eGFR was 98.2 ± 13.6 ml/min/1.73 m²; hyperfiltration (>120 ml/min/1.73 m²) was present in 7% of the cohort. No eGFR variation over the follow-up emerged, except at the last visit (-3.6 ± 1.4 ml/min/1.73 m² at month 48, p = 0.01 vs baseline). In the univariate analysis, the renal performance at 48 months was inversely related to baseline eGFR (r = -0.17, p = 0.04) and plasma triglycerides (r = -0.04, p = 0.05). Fasting and OGTT-derived variables did not impact eGFR. By multiple regression analysis, eGFR time course was independently predicted only by baseline eGFR (p = 0.03). Interestingly, patients having a baseline eGFR >100 ml/min/1.73 m² (median value) showed, after 48 months, an average loss of -8.3 ± 2.2 ml/min/1.73 m², while those with eGFR <100 exhibited a slight increase (+1.8 ± 2.3 ml/min/1.73 m², p < 0.01).

CONCLUSIONS

Long-term data confirm the safety of RYGB on renal function. Interestingly, a subtle hyperfiltration, i.e., occurring in high-normal range of eGFR, is attenuated by surgical procedure. Lastly, high serum triglycerides may track an unfavorable renal outcome.

Does bariatric surgery really prevent deterioration of renal function?

BACKGROUND

Obesity is related to impaired renal function; bariatric surgery is associated with an improvement in renal function.

OBJECTIVES

We investigated obesity-related changes in renal function after bariatric surgery and identified related clinical factors.

SETTING

Soonchunhyang University Seoul Hospital, Korea.

METHODS

From December 2011 to February 2014, 493 consecutive patients who met the criteria underwent bariatric surgery. Of these patients, 136 patients were enrolled. The exclusion criteria were as follows: revisional bariatric surgery, laparoscopic adjustable gastric banding, significant chronic kidney disease, macroalbuminuria, nephrotic range proteinuria, and absence of laboratory data on renal function. Overall, there were 126 patients with Roux-en-Y gastric bypass and 10 with sleeve gastrectomy. Preoperative and postoperative 1-year renal function was evaluated by the estimated glomerular filtration rate, urinary albumin-to-creatinine ratio (UACR), and urinary protein-to-creatinine ratio (UPCR).

RESULTS

Of 136 patients, 101 were women, and the mean age was 35.9±11.2 years. UACR was significantly lower postoperatively than preoperatively (27.0±47.2 versus 9.0±8.6 mg/g; P<.001). Microalbuminuria was present in 22.1% of patients preoperatively, decreasing to 4.4% 1-year postoperatively. A significant reduction was observed in the UPCR (90.7±101.2 versus 64.6±34.8 mg/g; P = .004). The mean value of estimated glomerular filtration rate improved from 117.8 to 119.6 mL/min/1.73 m(2), although this was not significant.

CONCLUSION

In obese patients, bariatric surgery significantly improves microalbuminuria and decreases the UACR and UPCR. Therefore, bariatric surgery should be considered as an early treatment for obesity with renal impairment and may prevent the progression to overt disease.

Deleterious Effects of Increased Intra-Abdominal Pressure on Kidney Function

Elevated intra-abdominal pressure (IAP) occurs in many clinical settings, including sepsis, severe acute pancreatitis, acute decompensated heart failure, hepatorenal syndrome, resuscitation with large volume, mechanical ventilation with high intrathoracic pressure, major burns, and acidosis. Although increased IAP affects several vital organs, the kidney is very susceptible to the adverse effects of elevated IAP. Kidney dysfunction is among the earliest physiological consequences of increased IAP. In the last two decades, laparoscopic surgery is rapidly replacing the open approach in many areas of surgery. Although it is superior at many aspects, laparoscopic surgery involves elevation of IAP, due to abdominal insufflation with carbonic dioxide (pneumoperitoneum). The latter has been shown to cause several deleterious effects where the most recognized one is impairment of kidney function as expressed by oliguria and reduced glomerular filtration rate (GFR) and renal blood flow (RBF). Despite much research in this field, the systemic physiologic consequences of elevated IAP of various etiologies and the mechanisms underlying its adverse effects on kidney excretory function and renal hemodynamics are not fully understood. The current review summarizes the reported adverse renal effects of increased IAP in edematous clinical settings and during laparoscopic surgery. In addition, it provides new insights into potential mechanisms underlying this phenomenon and therapeutic approaches to encounter renal complications of elevated IAP.

The effect of bariatric surgery on renal function and disease: a focus on outcomes and inflammation

Renal dysfunction and disease, including hyperfiltration, proteinuria and hypofiltration, are commonly associated with obesity. Diabetic kidney disease is also common in obese cohorts. Weight loss interventions, including bariatric surgery, can effectively reduce weight and improve renal outcomes. Some of this effect may be due to the remission of Type 2 diabetes and hypertension. However, other mechanisms, including the resolution of inflammatory processes, may also contribute. The effect of bariatric surgery on renal function has only recently become a focus of particular investigation. In this study, we will review the effects of bariatric surgery on obesity-associated kidney disease. We will discuss the pitfalls in assessing renal function in obese cohorts and will examine the effect of bariatric surgery on renal function and urinary protein excretion using different mechanisms. We will give particular attention to the evidence for bariatric surgery in cohorts with established renal disease and suggest future directions. In particular, we will outline the evidence for inflammation as an important therapeutic target, and the emerging medical therapies being considered to exploit this target in obesity- and diabetes-related kidney disease.