Association between obesity and kidney disease: a systematic review and meta-analysis

Trends in estimated kidney function: the FINRISK surveys

We evaluated the temporary trend in estimated glomerular filtration rate (eGFR) of subjects aged from 25 to 74 years between two cross-sectional population surveys in 2002 and in 2007. The mean eGFR across age-groups, the prevalences of eGFR categories, and the prevalence of chronic kidney disease (CKD) stage 3–5 defined by eGFR\60 mL/min/1.73 m2 were defined in sex- and age-specific groups using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) Study equation. The eGFR decreased from year 2002 to 2007 across the age-groups in both genders. The prevalence of CKD stage 3–5 (eGFR\60 mL/min/1.73) increased in women from 1.8 to 3.1% (P=0.017), but not in men. In the combined analysis of both genders, CKD stage 3–5 was markedly more common in 2007 compared to 2002, with odds ratio (OR) 1.59 (95% confidence interval (CI) 1.22–2.08) remaining significant after adjusting the model for age, gender, study area, hypertension, obesity, prior cardiovascular disease, and diabetes mellitus, and being at lowest when only age, gender and waist circumference were included in the model (OR 1.34; 95% CI 1.02–1.76). To conclude, the mean eGFR decreased significantly during 2002–2007 in both sexes, and CKD stage 3–5 increased in women. This trend was concurrent with increases in mean waist circumference and in the prevalence of diabetes mellitus.

Reducing the load: the evolution and management of obesity and nonalcoholic steatohepatitis before liver transplantation

1. Obesity is common in patients with end-stage liver disease of any cause. 2. Obesity is associated with comorbidities that can affect liver transplant candidacy, such as metabolic syndrome (diabetes, hyperlipidemia, and hypertension), cardiovascular disease, pulmonary disorders (related to obstructive sleep apnea), renal dysfunction, and malignancies. 3. Nonalcoholic steatohepatitis is the only indication for transplantation that is increasing in frequency, and it may soon become the leading indication. 4. There is no set body mass index above which liver transplantation is contraindicated. Transplant candidacy and outcomes depend on the cumulative comorbidities of the individual patient. 5. Weight loss is an important component of metabolic syndrome management and is recommended before liver transplantation. 6. Bariatric surgery may be considered in carefully selected patients with well-compensated cirrhosis but is not recommended in patients with decompensated cirrhosis.

Effects of bariatric surgery on diabetic nephropathy after 5 years of follow-up

BACKGROUND

Studies have reported that the benefits of bariatric surgery extend beyond durable weight loss and include significant improvement in glycemic control. We hypothesized that improving diabetes control may have positive effects on end-organ complications of this disease, such as diabetic nephropathy (DN).

METHODS

We identified all patients with type 2 diabetes mellitus (T2DM) who underwent bariatric surgery at our institution and had completed a 5-year follow-up. Patients' current diabetes status (remission, improvement, or no change) was determined by biochemical analyses and medication review. The presence of DN, preoperatively and postoperatively, was determined by urinary albumin/creatinine ratio (uACR).

RESULTS

Fifty-two T2DM patients underwent bariatric surgery and had completed 5-year follow-up, including serial uACR measurements (25% male; age 51.2 ± 10.1 years). Preoperative body mass index (BMI) was 49 ± 8.7 kg/m(2), mean duration of T2DM was 8.6 years (range .3-39), and baseline HbA(1c) was 7.7% ± 1.4%. DN, as indicated by microalbuminuria (30-300 mg/g) or macroalbuminuria (>300 mg/g), was present in 37.6% preoperatively. Of these, DN resolved in 58.3% at a mean follow-up of 66 months (range 60-92 ). Among those with no evidence of DN preoperatively, albuminuria proceeded to develop 5 years later in only 25%. The 5-year remission and improvement rates for T2DM were 44% and 33%, respectively. Mean reductions in fasting glucose and glycosylated hemoglobin (HbA(1c)) were 36.6 mg/dL and 1.2%, respectively.

CONCLUSION

Bariatric surgery can induce a significant and sustainable improvement in T2DM and improve or halt the development of microvascular complications such as nephropathy. Considering that diabetes is often a progressive disease, these results are clinically important and warrant further investigation.

The impact of renal function on outcomes of bariatric surgery

The effect of CKD on the risks of bariatric surgery is not well understood. Using the American College of Surgeons National Surgical Quality Improvement Program Participant Use File, we analyzed 27,736 patients who underwent bariatric surgery from 2006 through 2008. Before surgery, 34 (0.12%) patients were undergoing long-term dialysis. Among those not undergoing dialysis, 20,806 patients (75.0%) had a normal estimated GFR or stage 1 CKD, 5011 (18.07%) had stage 2 CKD, 1734 (6.25%) had stage 3 CKD, 94 (0.34%) had stage 4 CKD, and 91 (0.33%) had stage 5 CKD. In an unadjusted analysis, CKD stage was directly associated with complication rate, ranging from 4.6% for those with stage 1 CKD or normal estimated GFR to 9.9% for those with stage 5 CKD (test for trend, P<0.001). Multivariable logistic regression demonstrated that CKD stage predicts higher complication rates (odds ratio for each higher CKD stage, 1.30) after adjustment for diabetes and hypertension. Although patients with higher CKD stage had higher complication rates, the absolute incidence of complications remained <10%. In conclusion, these data demonstrate higher risks of bariatric surgery among patients with worse renal function, but whether the potential benefits outweigh the risks in this population requires further study.

Epidemiology of chronic kidney disease in children

In the past 30 years there have been major improvements in the care of children with chronic kidney disease (CKD). However, most of the available epidemiological data stem from end-stage renal disease (ESRD) registries and information on the earlier stages of pediatric CKD is still limited. The median reported incidence of renal replacement therapy (RRT) in children aged 0-19 years across the world in 2008 was 9 (range: 4-18) [corrected] per million of the age-related population). [corrected] The prevalence of RRT in 2008 ranged from 18 to 100 per million of the age-related population. Congenital disorders, including congenital anomalies of the kidney and urinary tract (CAKUT) and hereditary nephropathies, are responsible for about two thirds of all cases of CKD in developed countries, while acquired causes predominate in developing countries. Children with congenital disorders experience a slower progression of CKD than those with glomerulonephritis, resulting in a lower proportion of CAKUT in the ESRD population compared with less advanced stages of CKD. Most children with ESRD start on dialysis and then receive a transplant. While the survival rate of children with ERSD has improved, it remains about 30 times lower than that of healthy peers. Children now mainly die of cardiovascular causes and infection rather than from renal failure.

Overweight and obesity accelerate the progression of IgA nephropathy: prognostic utility of a combination of BMI and histopathological parameters

BACKGROUND

Although more than 40 years have passed since IgA nephropathy (IgAN) was first reported, predicting the renal outcome of individual IgAN patients remains difficult. Emerging epidemiologic evidence indicates that overweight and obesity are risk factors for end-stage renal disease. We aimed to elucidate the outcome of overweight IgAN patients and improve our ability to predict the progression of IgAN based on a combination of body mass index (BMI) and histopathological parameters, including maximal glomerular area (Max GA).

METHODS

Forty-three adult IgAN patients whose estimated glomerular filtration rate was ≥50 ml/min/1.73 m(2) were enrolled in this study. Renal biopsy specimens were evaluated according to the Oxford classification of IgAN. A Kaplan-Meier analysis and the multivariate Cox proportional hazards method were used to evaluate 10-year kidney survival and the impact of covariates. The ability of factors to predict the progression of IgAN was evaluated by their diagnostic odds ratio (DOR).

RESULTS

A BMI ≥25 kg/m(2) was found to be an independent predictor of a ≥1.5-fold increase in serum creatinine value (DOR 7.4). The combination of BMI ≥25 kg/m(2), Max GA ≥42,900 μm(2), and presence of mesangial hypercellularity (Oxford M1) optimally raised predictive power for disease progression of IgAN (DOR 26.0).

CONCLUSION

A combination of BMI ≥25 kg/m(2), the Oxford classification M1, and a Max GA ≥42,900 μm(2) can serve as a predictor of long-term renal outcome of IgAN.

Overweight, obesity and intentional weight loss in chronic kidney disease: NHANES 1999-2006

Objective

Obesity and chronic kidney disease (CKD) have emerged as major public health problems. We aimed to examine: a) lifestyle and behavioral factors, b) factors related to pursuing weight loss, and c) weight loss modalities pursued by CKD and non-CKD individuals who are overweight and obese.

Methods

Cross-sectional analysis of 10,971 overweight and obese adult participants in the National Health and Nutrition Examination Surveys conducted between 1999-2006. We examined the differences in lifestyle and behavioral factors between CKD and non-CKD participants and factors associated with pursuing weight loss using survey regression models.

Results

The total daily energy intake of the CKD population was lower than the non-CKD group (1987 kcal/day vs. 2063 kcal/day, p=0.02) even after adjusting for relevant covariates. However, the percentage of energy derived from protein was similar between the groups. Sixty-six percent of the CKD population did not meet the minimum recommended leisure time physical activity goals compared to 57% among non-CKD (p<0.001). Fifty percent of CKD participants pursued weight loss (vs. 55% of non-CKD individuals, p=0.01), but the presence of CKD was not independently associated with the pursuit of weight loss in the multivariate model. Among participants pursuing weight loss, modalities including dietary interventions utilized by CKD and non-CKD participants were similar. Eight percent of CKD participants used medications to promote weight loss.

Conclusions

Among the overweight and obese population, lifestyle and behavioral factors related to obesity and weight loss are similar between CKD and non-CKD participants. Insufficient data exist on the beneficial effects of intentional weight loss in CKD and these data show that a significant proportion of the CKD population use diets that may have high protein content and medications to promote weight loss that may be harmful. Future clinical trials evaluating the efficacy and optimal modalities to treat obesity in the CKD population are warranted.

Obesity-related glomerulopathy and podocyte injury: a mini review

Obesity-related glomerulopathy (ORG) is morphologically defined as focal segmental glomerulosclerosis and glomerulomegaly. Podocyte hypertrophy and reduced density are related to proteinuria which in a portion of patients is in the nephrotic range and evolvs towards renal failure. This article reviews the pathogenetic mechanisms of podocyte injury or dysfunction and lists new possible antiproteinuric strategies based on pharmaceutical targeting of the reported pathogenetic mechanisms. The pathogenetic mechnisms discussed include: renin angiotensin system, plasminogen activation inhibitor-1 (PAI-1), lipid metabolism, adiponectin, macrophages and proinflammatory cytokines, oxidative stress. The proposed antiproteinuric strategies include: AT2 receptor blockers; adipokine complement C19 TNF-related protein-1 blocker; selective PAI-1 inhibitor; farnesoid x receptor activation; increase of circulating adiponectin; selective antiinflammatory drugs; more potent antioxidants (Heme oxigenase, NOX4 inhibitors). However, because ORG is a rare disease, the need for a long term pharmaceutical approach in obese proteinuric patients should be carefully evaluated and limited to the cases with progressive loss of renal function.

Management of obesity-induced kidney disease: a critical review of the literature

It is well established that obesity is a risk factor for the development of chronic kidney disease (CKD) and may promote the progression to end stage renal disease (ESRD). Therefore, it is strongly suggested that reduction of body weight can be an important intervention in order to reduce the prevalence of renal impairment. The current article describes extensively the already published trials which have studied the association between weight loss and kidney disease. The weight management programs include surgical and non-surgical interventions (low-calorie diet, aerobic exercise, drug-induced weight loss, combination treatment). The focus has been placed on the following renal function markers: albuminuria, proteinuria, glomerular filtration rate (GFR), and creatinine clearance. This review also aims to clarify challenges that clinicians have to deal with in everyday practice regarding the management of obesity-induced kidney disease (degree of weight loss, duration of the weight loss program, early initiation of the intervention).

Evaluation of microalbuminuria in obese children and its relation to metabolic syndrome

Several epidemiologic studies have clearly demonstrated that obesity increases the risk of kidney diseases. We have attempted to evaluate the association of obesity with albuminuria, an early marker of kidney disease, among obese children and its relation to metabolic syndrome. This study included 150 obese children. Blood pressure, fasting blood glucose, plasma insulin and the lipid profile were assessed. The homeostasis model assessment of insulin resistance (HOMA-IR) was used to calculate in vivo insulin resistance. Urinary albumin and creatinine were estimated. Microalbuminuria was detected in 22 (14.7%) of the obese children. Waist circumference, blood pressure, triglyceride, low-density lipoprotein (LDL), insulin resistance and fasting blood glucose were significantly higher in obese children with microalbuminuria than in those with normoalbuminuria and showed significant positive correlations with microalbuminuria. High-density lipoprotein (HDL) was significantly lower in obese children with microalbuminuria than in those with normoalbuminuria, with a significant negative correlation with microalbuminuria. We found that body mass index, abdominal obesity, hypertension, impaired fasting glucose level and insulin resistance significantly increased the odds of microalbuminuria in the obese children enrolled in this study. Moreover, high triglyceride, high LDL and low HDL were significantly associated with microalbuminuria. In our patient group, childhood obesity was a risk factor for the development of microalbuminuria, which in turn was significantly associated with metabolic syndrome and its different constituents.

Coping with perceived racism: a significant factor in the development of obesity in African American women?

BACKGROUND

African American women have the highest rates of obesity in the United States. The prevalence of obesity in this group calls for the identification of psychosocial factors that increase risk. Psychological stress has been associated with obesity in women; however, there is scant literature that has explored the impact of racism on body mass index (BMI) in African American women.

OBJECTIVE

The current study aimed to determine whether emotional responses and behavioral coping responses to perceived racism were associated with BMI in African American women.

METHODS

A sample of 110 African American women participated in a community-based study. Height and weight measurements were taken to calculate BMI and participants completed the Perceived Racism Scale and the Perceived Stress Scale.

RESULTS

Hierarchical regression analyses demonstrated a significant relationship between BMI and behavioral coping responses to perceived racism. Findings for emotional responses to perceived racism and appraisal of one's daily life as stressful were nonsignificant. Mean comparisons of BMI groups showed that obese African American women used more behavioral coping responses to perceived racism as compared to normal-weight and overweight women in the sample.

CONCLUSION

Findings suggest that behavioral coping responses better explained increased risk for obesity in African American women. A biobehavioral pathway may explain this finding with a stress-response process that includes cortisol reactivity. Maladaptive behavioral coping responses may also provide insight into obesity risk. Future research is needed to determine which behavioral coping responses place African American women at greater risk for obesity.

Metabolic syndrome and kidney disease: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

Observational studies have reported an association between metabolic syndrome (MetS) and microalbuminuria or proteinuria and chronic kidney disease (CKD) with varying risk estimates. We aimed to systematically review the association between MetS, its components, and development of microalbuminuria or proteinuria and CKD. DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS AND POPULATION: We searched MEDLINE (1966 to October 2010), SCOPUS, and the Web of Science for prospective cohort confidence interval (CI) studies that reported the development of microalbuminuria or proteinuria and/or CKD in participants with MetS. Risk estimates for eGFR <60 ml/min per 1.73 m(2) were extracted from individual studies and pooled using a random effects model. The results for proteinuria outcomes were not pooled because of the small number of studies.

RESULTS

Eleven studies (n = 30,146) were included. MetS was significantly associated with the development of eGFR <60 ml/min per 1.73 m(2) (odds ratio, 1.55; 95% CI, 1.34, 1.80). The strength of this association seemed to increase as the number of components of MetS increased (trend P value = 0.02). In patients with MetS, the odds ratios (95% CI) for development of eGFR <60 ml/min per 1.73 m(2) for individual components of MetS were: elevated blood pressure 1.61 (1.29, 2.01), elevated triglycerides 1.27 (1.11, 1.46), low HDL cholesterol 1.23 (1.12, 1.36), abdominal obesity 1.19 (1.05, 1.34), and impaired fasting glucose 1.14 (1.03, 1.26). Three studies reported an increased risk for development of microalbuminuria or overt proteinuria with MetS.

CONCLUSIONS

MetS and its components are associated with the development of eGFR <60 ml/min per 1.73 m(2) and microalbuminuria or overt proteinuria.

AMPK mediates the initiation of kidney disease induced by a high-fat diet

The mechanisms underlying the association between obesity and progressive renal disease are not well understood. Exposure to a high-fat diet decreases levels of the cellular energy sensor AMPK in many organs, including the kidney, but whether AMPK contributes to the pathophysiology of kidney disease induced by a high-fat diet is unknown. In this study, we randomly assigned C57BL/6J mice to a standard or high-fat diet. After 1 week, mice fed a high-fat diet exhibited an increase in body weight, renal hypertrophy, an increase in urine H(2)O(2) and urine MCP-1, and a decrease in circulating adiponectin levels and renal AMPK activity. Urine ACR progressively increased after 4 weeks of a high-fat diet. After 12 weeks, kidneys of mice fed a high-fat diet demonstrated a marked increase in markers of fibrosis and inflammation, and AMPK activity remained significantly suppressed. To determine whether inhibition of AMPK activity explained these renal effects, we administered an AMPK activator along with a high-fat diet for 1 week. Although AMPK activation did not abrogate the weight gain, it reduced the renal hypertrophy, urine H(2)O(2), and urine and renal MCP-1. In vitro, AMPK activation completely inhibited the induction of MCP-1 by palmitic acid in mesangial cells. In conclusion, these data suggest that the energy sensor AMPK mediates the early renal effects of a high-fat diet.

Metabolic syndrome, insulin resistance and kidney function in non-diabetic individuals

BACKGROUND

Metabolic syndrome has been recently identified as a risk factor for chronic kidney disease (CKD). Since the five individual components of the metabolic syndrome have also been identified as risk factors for CKD, the metabolic syndrome diagnosis may represent an aggregate of CKD risk factors. On the other hand, the components of the metabolic syndrome are also associated with insulin resistance, which may directly mediate the increased CKD risk.

METHODS

This study was a cross-sectional evaluation of the relationship between metabolic syndrome, insulin resistance and estimated glomerular filtration rate (eGFR) in 574 non-diabetic individuals. Insulin resistance was directly quantified using the insulin suppression test, and the metabolic syndrome components were measured. eGFR was calculated using the three validated estimation equations: the Chronic Kidney Disease Epidemiology Collaboration equation, the Mayo quadratic equation and the Modification of Diet in Renal Disease study equation.

RESULTS

While CKD prevalence was higher and mean eGFR was lower in individuals who met the metabolic syndrome criteria compared with those who did not, we did not observe a significant relationship between insulin resistance and eGFR. Of all of the components of the metabolic syndrome, only hypertension was significantly associated with CKD prevalence [odds ratio (95% confidence interval), 3.5 (1.2-10.1), P=0.02].

CONCLUSION

Although CKD is more common among individuals with the metabolic syndrome, insulin resistance is not a common factor.

Metabolic syndrome, insulin resistance and kidney function in non-diabetic individuals

BACKGROUND

Metabolic syndrome has been recently identified as a risk factor for chronic kidney disease (CKD). Since the five individual components of the metabolic syndrome have also been identified as risk factors for CKD, the metabolic syndrome diagnosis may represent an aggregate of CKD risk factors. On the other hand, the components of the metabolic syndrome are also associated with insulin resistance, which may directly mediate the increased CKD risk.

METHODS

This study was a cross-sectional evaluation of the relationship between metabolic syndrome, insulin resistance and estimated glomerular filtration rate (eGFR) in 574 non-diabetic individuals. Insulin resistance was directly quantified using the insulin suppression test, and the metabolic syndrome components were measured. eGFR was calculated using the three validated estimation equations: the Chronic Kidney Disease Epidemiology Collaboration equation, the Mayo quadratic equation and the Modification of Diet in Renal Disease study equation.

RESULTS

While CKD prevalence was higher and mean eGFR was lower in individuals who met the metabolic syndrome criteria compared with those who did not, we did not observe a significant relationship between insulin resistance and eGFR. Of all of the components of the metabolic syndrome, only hypertension was significantly associated with CKD prevalence [odds ratio (95% confidence interval), 3.5 (1.2-10.1), P=0.02].

CONCLUSION

Although CKD is more common among individuals with the metabolic syndrome, insulin resistance is not a common factor.

A diet with 35% of energy from protein leads to kidney damage in female Sprague-Dawley rats

High-protein (HP) diets for weight loss remain popular despite questions surrounding overall safety. In a recent study using the pig model, we showed that long-term intakes from whole proteins at 35 % energy (en %) cause moderate renal histological damage. To examine whether this observation may be species specific or more generalisable, the effect of this diet in rats was examined. Using plant and animal whole proteins, 70-d-old female Sprague-Dawley rats were randomised to either a normal-protein (NP; 15 en %) or a HP (35 en %) diet for 4, 8, 12 and 17 months. Renal function was assessed by creatinine clearance and urinary protein levels, and pathology was assessed by examination of glomerular hypertrophy, glomerulosclerosis and tubulointerstitial fibrosis. Rats consuming the HP diet had 17 % higher kidney weights (P < 0·0001), three times higher proteinuria (P < 0·0001) and 27 % higher creatinine clearance (P = 0·0012) compared with those consuming the NP diet. Consistent with this, HP-fed rats had larger glomeruli (P < 0·0001) and more glomerulosclerosis (P = 0·0003) compared with NP-fed rats. The HP diet also resulted in altered levels of free monocyte chemoattractant protein-1 (P < 0·0001). The histological changes are consistent with those observed in the pig model. In contrast to the pig model, the elevated proteinuria and creatinine clearance observed in the rat model are also usually observed with HP consumption in human subjects. These results indicate that the rat is a useful model for HP effects on the kidney and, along with previous results using the pig model, suggest that long-term intake of high levels of protein may be detrimental to renal health.

Hypertension in Cardiovascular and Kidney Disease

The relationship between hypertension and chronic kidney disease (CKD) is bidirectional in nature and, generally, management strategies for cardiovascular risk reduction also attenuate progression of CKD. Prevalent hypertension increases with diminishing kidney function, and the management strategy changes with level of kidney function. In this review, we will examine the evidence for management of hypertension, as a modifiable risk factor for cardiovascular disease in CKD, and the impact of this management on progression of CKD.

Bariatric surgery and renal function

Obesity causes a significant healthcare burden and has been shown to be an important risk factor in the development of cardiovascular disease, type 2 diabetes, and increasingly chronic kidney disease. Bariatric surgery is the most effective treatment for obesity and has been shown to drastically improve both blood pressure and diabetic control. However, the interaction of bariatric surgery and renal function is less clear. This review focuses on the effect of bariatric surgery on renal function both in the acute situation, with respect to acute kidney injury, and also on changes in renal function parameters post-bariatric surgery weight loss. The interaction of obesity, bariatric surgery, and nephrolithiasis as a precipitant of acute kidney injury will also be considered. The role of bariatric surgery in pre- and post-renal transplant recipients is discussed as well as possible mechanisms underlying the improvement in renal function.

Glomerular number and size variability and risk for kidney disease

PURPOSE OF REVIEW

This review discusses current understandings of variability in glomerular number and size, and the implications for renal health.

RECENT FINDINGS

The quantitative microanatomy of the normal human kidney varies widely. Of greatest significance, total nephron number varies at least 13-fold, and several genes and environmental factors that regulate human nephron endowment have been identified. Full or partial deletion of more than 25 genes in mice has been shown to result in renal hypoplasia and, when measured, reduced nephron endowment. Many more will likely be identified. As would be expected, some gene abnormalities increase nephron endowment above that found in control mice. Glomerular volume also varies widely, both between and within kidneys, and increased heterogeneity of glomerular volume within kidneys is associated with risk factors for kidney disease, including birth weight, age, race, body size and hypertension.

SUMMARY

Data from several human populations indicate that the quantitative microanatomy of the human kidney varies considerably: total glomerular number varies at least 13-fold, mean glomerular volume varies up to seven-fold and the volumes of individual glomeruli within single kidneys can vary as much as eight-fold. Human glomerular number, size and size distribution are being found to correlate with risk factors for kidney disease. The genetic and fetal environmental regulators of nephrogenesis, and thereby nephron endowment, are being rapidly identified and will provide the bases for future clinical interventions. In contrast, the molecular regulation of glomerular size remains unclear.

The role of obesity in kidney disease: recent findings and potential mechanisms

Obesity epidemic is in rise in almost every industrialized country and continues to be a growing problem worldwide. In fact, obesity per se has been recognized as a chronic disease. Consequently, there has been a cascade of metabolic changes initiated by the markedly risen prevalence that contributes to the increased incidence of diabetes, hypertension, and cardiovascular disease. Moreover, obesity is also associated with an increased risk of chronic kidney disease (CKD). The majority of the studies indicate a direct relationship between body mass index (BMI) and CKD risk. Moreover, current evidence emphasized the fact that central obesity measurements, such as waist circumference, could be a better predictor of CKD progression and mortality than BMI. The detrimental effects of obesity on kidney outcome have been recognized in nondialysis-dependent (NDD)-CKD patients. However, survival in overweight or obese CKD patients undergoing maintenance hemodialysis is paradoxically opposed compared with the general population. This "reverse epidemiology," however, is valid mainly for the inflammated end-stage renal disease (ESRD) patients. In fact, renal transplant recipients with higher BMI have inferior patient and graft survival compared to patients with lower BMI. This review also provides perspectives concerning the mechanisms associated with obesity, such as the renin-angiotensin-aldosterone system (RAAS) activation, and the role of leptin, adiponectin, fetuin-A, and adipose tissue, as factors that contribute to the development of CKD. Prevention strategies for CKD patients are also discussed and should be considered by clinicians.

The effect of obesity on chronic kidney disease

Overweightness and obesity are associated with many hemodynamic, structural, and histopathologic alterations in the kidney and with metabolic and biochemical changes that predispose to these abnormalities. Consequent to these disorders, these individuals are more likely to develop chronic kidney disease and end-stage renal failure. Overweight and obese people are more prone to develop albuminuria and, for at least some types of kidney disease, a greater amount of albuminuria and more rapid progression of renal failure. These individuals are more likely to develop diabetes mellitus and hypertension. Diabetic nephropathy, hypertensive nephrosclerosis, focal and segmental glomerulosclerosis, renal cell carcinoma, and urate and calcium oxalate urolithiasis are the more common kidney and urological diseases reported in obese people. Preliminary data indicate that many of the clinical and nephropathologic manifestations associated with obesity can be reversed or ameliorated with reductions in body fat induced by dietary energy restriction or surgical procedures that reduce intake and gastrointestinal absorption of calories.

Implications for kidney disease in obese children and adolescents

Increasing attention has been focused on the implications of obesity in adults on the development of kidney disease, but data on the obese pediatric population are lacking. The aim of this study was to investigate whether changes in various renal function indexes/markers, as expressed by the glomerular filtration rate [GFR, as estimated by the Schwartz formula (eGFR)], serum cystatin C (CysC) level, albumin excretion rate (AER), and modifications in nitric oxide (NO; an important modulator of renal function and morphology), urinary isoprostanes (markers of oxidative stress), and blood pressure (BP), can be detected in obese children and adolescents when compared to normal weight controls. Blood and urinary samples were collected to evaluate markers of renal function, serum and urinary NO, and urinary isoprostanes in 107 obese Caucasian subjects and 50 controls. Ambulatory BP monitoring (ABPM) was performed in all cases. Obesity was expressed by the body mass index standard deviation score (SDS-BMI), and insulin resistance by the homeostasis model assessment of insulin resistance (HOMA-IR). CysC and eGFR did not significantly differ between the two groups; AER was increased in obese children. CysC and GFR were related to HOMA-IR, and AER was related to HOMA-IR and SDS-BMI. Obese subjects had reduced NO levels and increased urinary isoprostanes and BP measurements; all three parameters were related to SDS-BMI and insulin resistance. ABPM showed an increased incidence of hypertension and non-dipping in the obese group. Based on our comparison of obese and nonobese children, we conclude that renal involvement is not an early clinically evident manifestation of adiposity in childhood, since no overt changes in eGFR and only a mild albuminuria were detected. A longer exposure to obesity is probably needed before renal function impairment appears.

Weight loss: a neglected intervention in the management of chronic kidney disease

PURPOSE OF REVIEW

Obesity is being increasingly implicated as an independent risk factor for the development of chronic kidney disease (CKD), raising the question whether reversing obesity can be utilized as a mainstay or an adjunct therapy for CKD and possibly for its prevention. The purpose of this review is to examine the impact of treatment of obesity on renal outcomes.

RECENT FINDINGS

Many observations have pointed to improvement in renal parameters following weight loss. In fact, both surgical and nonsurgical approaches appear to be effective at reducing blood pressure and proteinuria. Weight loss has also been shown to lower glomerular filtration rate (GFR) in obese patients, not an insignificant benefit considering that intra-glomerular hypertension and the subsequent hyperfiltration in the setting of obesity might be a main driver for the development of CKD.

SUMMARY

Urinary protein excretion, blood pressure, and GFR improve with surgical and nonsurgical weight loss interventions. Whether improvements in these surrogate outcomes after weight loss actually translate into a reduction in the risk of CKD or amelioration in the rate of progression of established CKD is yet to be determined.

[Renal consequences of obesity]

The steady increase in the prevalence of obesity contributes to the increase in the prevalence of chronic kidney disease, through renal damages associated with type-2 diabetes and hypertension. Obesity is also an independent risk factor for the kidney, since it is associated with an increased risk of albuminuria and glomerulosclerosis, and worsens the course of chronic kidney disease regardless of the primary renal disease. The existence of a metabolic syndrome, constant in type-2 diabetes, and associated with abdominal obesity, is not the only requirement for renal anomalies of which the translation is a functional hyperfiltration, a clinical microalbuminuria and histologically a glomerulomegaly and glomerulosclerosis. The estimated glomerular filtration rate (GFR) in obese patients is strongly influenced by the weight or indexation to body surface area, and it is logical to take into account the value of non-indexed GFR to assess renal risk and treatment effects, especially if they lead to weight loss. Hypertension is promoted by salt sensitivity, potentially reversible, and overactivity of the renin-angiotensin system (RAS) in part due to adipose tissue. The cytokines secreted by adipose tissue (adipokines), induce sympathetic hyperactivity through leptin, and low-grade inflammatory state that contributes to the development of glomerular sclerosis lesions, especially because a resistance to adiponectin. The treatment relies on weight loss, possibly through bariatric surgery, and antagonists of the RAS.

Weight loss in obese patients with chronic kidney disease: who and how?

Obesity has adverse consequences in the general population. In patients with chronic kidney disease (CKD), it is associated with increased inflammation, insulin resistance, hypertension and dyslipidaemia, which are important risk factors for CKD progression and death. In adults with CKD stages 1-4, weight loss should be encouraged, it reduces proteinuria and glomerular hyperfiltration, which are frequent in obese patients. Proposals for modifications of lifestyle, physical activity and calorie restriction are the first measures. Pharmacological treatments are generally unsafe in these patients, except orlistat, but that has modest efficacy. Bariatric surgery may be the only option in severe obesity, if all other measures fail. For obese patients on dialysis treatment, who are eligible for kidney transplantation, weight loss is mandatory to prevent obesity-related surgical complications and improve patient and graft survival after transplantation. Interventions should place an emphasis on exercise to increase muscle mass, and calorie but not protein restriction. Bariatric surgery should be carried out by experienced surgeons due to the high risk of complications. For obese patients who are not considered transplant candidates the benefits of weight loss remain uncertain.

Evaluation of metabolic risk marker in obesity-related glomerulopathy

OBJECTIVE

Insulin resistance is a common metabolic abnormality, which increases the risk of renal events in obesity. The present study is aimed to examine the relation between metabolic factors and obesity-related glomerulopathy (ORG), and then compare the risk markers of insulin resistance for clinical prediction.

METHODS

A total of 112 cases with proven renal ORG and 135 age- and gender-matched lean controls were included. The degree of proteinuria, endogenous creatinine clearance rate, body mass index, amylin, fasting glucose, insulin, lipid and lipoprotein concentrations were measured during the steady state.

RESULTS

The patients with ORG were clinically characterized by increased body mass index and proteinuria, with higher levels of amylin, homeostasis model assessment of insulin resistance (HOMA-IR), insulin, glucose, and lipid proteins when compared with the lean controls. Multiple logistic regression analysis revealed that amylin and HOMA-IR were significantly associated with the prevalence of ORG. In patients with ORG, proteinuria level correlated with amylin, total cholesterol, fasting insulin, and HOMA-IR. Moreover, proteinuria correlated positively with HOMA-IR and amylin in a multiple regression analysis. In addition, the endogenous creatinine clearance rate did not correlate with any metabolic marker.

CONCLUSION

This study suggested that screening for HOMA-IR might have predictive value for renal damage in obese patients. In addition to insulin resistance, amylin also showed positive effects on evaluation of such renal impairment.

The burden of kidney disease in indigenous children of Australia and New Zealand, epidemiology, antecedent factors and progression to chronic kidney disease

AIMS

To review and present the most important issues related to kidney disease in Aboriginal, Torres Strait Islander, Maori and Pacific Islander children from Australia and New Zealand.

METHODS

A review of medical literature about: 1. incidence of kidney disease in Indigenous children in Australia and New Zealand, especially where rates are different from the general populations, 2. factors in early life which increase risk for chronic kidney disease in adult life, and 3. early identification and primary and secondary interventions in childhood which may prevent chronic kidney disease in adults.

RESULTS

Kidney diseases, both acute and chronic are more common in Maori, Pacific Islander, Australian Aboriginal and Torres Strait Islander people. The reasons are multiple and include genetic, environmental and socio-economic factors. In childhood post streptococcal glomerulonephritis, haemolytic uraemic syndrome, renal stones and acute kidney injury all occur at higher frequency in at least some of the Indigenous populations. Chronic kidney disease CKD occurs more commonly, and at a younger age in Indigenous than non Indigenous people. Factors involved may include reduced nephron endowment at birth, and subsequent insults including nephritis, obesity, and early onset type 2 diabetes, as well as underlying socioeconomic and environmental determinants.

CONCLUSION

A lifecourse understanding allows one to conceptualise multiple risk factors and target interventions.

Para- and perirenal fat thickness is an independent predictor of chronic kidney disease, increased renal resistance index and hyperuricaemia in type-2 diabetic patients

BACKGROUND

Many interfering factors may reduce the reliability of waist circumference (WC) measurement in estimating the risk for chronic kidney disease (CKD) associated with obesity. Therefore, we determined the independent associations of para- and perirenal ultrasonographic fat thickness with the main markers of kidney function.

METHODS

A cross-sectional study was performed in 151 type-2 diabetic subjects. Para- and perirenal fat thickness was measured from the inner side of the abdominal musculature to the surface of the kidneys. CKD was defined as eGFR < 60 mL min(-1)1.73 m(-2).

RESULTS

Using both univariate and multivariate regression analyses, eGFR, renal resistance index and uricaemia were best predicted by para- and perirenal fat thickness even when BMI and waist circumference were further added in the statistical model (r(2): 0.366, P = 0.001; r(2): 0.529, P = 0.005; r(2): 0.310, P = 0.026, respectively), whereas waist circumference and BMI did not contribute independently of para- and perirenal fat thickness. Albuminuria was predicted by waist circumference but not by para- and perirenal fat thickness. In subjects with waist circumference above the diagnostic values of metabolic syndrome (48M/59F), eGFR significantly and progressively declined across tertiles of para- and perirenal fat thickness (87.0 ± 27.9 vs 83.5 ± 26.0 vs 62.3 ± 30.6 mL min(-1) 1.73 m(-2), adjusted P < 0.0001) despite comparable waist circumference, and an increasing frequency of CKD was observed across tertiles of subjects with waist circumference both below and above the metabolic syndrome diagnostic values (P < 0.05).

CONCLUSIONS

Para- and perirenal fat thickness is an independent predictor of kidney dysfunction in type-2 diabetes explaining an important proportion of the variance of eGFR, renal resistance index and uricaemia.

Independent influence of dietary protein on markers of kidney function and disease in obesity

Obesity is associated with glomerular hyperfiltration and increased urinary protein excretion, as well as structural and functional changes that lead to kidney disease and failure. Dietary protein mimics obesity's effects on the glomerular filtration rate (GFR) and proteinuria and, in certain circumstances, may have the potential to adversely affect kidney function. Here we tested the hypothesis that dietary protein independently explains elevations in the GFR and proteinuria found in obese persons with a normal serum creatinine. Seventeen patients were randomized in a double-blind, crossover fashion for 1-week periods to high (140 g/day) and low (50 g/day) protein diets with a 1-week washout interval separating these periods. High protein consumption was associated with a very modest but significant increase in the GFR of 5 ± 6 ml/min. Hence, while dietary protein does modulate kidney parameters, it is unlikely to fully account for the elevations in GFR and proteinuria found in obesity.

Practical management of diet and lifestyle interventions for people with diabetes or cardiovascular disease

Increased collaboration between the vascular specialities is clearly leading to increased understanding of the interrelationships between the different disease states and how each impacts and influences the other. This advantage will be reflected in improved patient care if the practical outputs of this growing knowledge are carefully implemented at service level. This article outlines how the aspects of diet and lifestyle associated with vascular-related disease complement, contrast and in some cases contradict each other. It gives information and guidelines as to how the expertise of dietitians working in the different specialist areas might usefully be shared to be of maximum advantage to all patients.

Marked association between obesity and glomerular hyperfiltration: a cross-sectional study in an African population

BACKGROUND

Obesity and African American ethnicity are established independent risk factors for the development of chronic kidney disease. No data exist about the association between obesity and renal hemodynamics in the African region.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

301 nondiabetic participants (97 lean, 108 overweight, and 96 obese) of African descent with a positive family history of hypertension from the Seychelles islands.

PREDICTOR

Body mass index (BMI).

OUTCOMES

Glomerular hyperfiltration, glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and filtration fraction.

MEASUREMENTS

GFR and ERPF were measured using inulin and para-aminohippurate clearances, respectively. Participants' baseline demographics, laboratory data, and blood pressure were measured using standard techniques.

RESULTS

The prevalence of glomerular hyperfiltration (defined as GFR >or=140 mL/min) increased across BMI categories (7.2%, 14.8%, and 27.1% for lean, overweight, and obese participants, respectively; P < 0.001). Higher BMI was associated with higher median GFR (99, 110, and 117 mL/min for lean, overweight, and obese participants, respectively; P < 0.001), ERPF (424, 462, and 477 mL/min, respectively; P = 0.01), and filtration fraction (0.23, 0.24, and 0.25; P < 0.001). Multivariate analyses adjusting for age, sex, blood pressure, fasting glucose level, and urinary sodium excretion and accounting for familial correlations confirmed the associations between high BMI (>25 kg/m(2)) and increased GFR, ERPF, and filtration fraction. No association between BMI categories and GFR was found with adjustment for body surface area.

LIMITATIONS

Participants had a positive family history of hypertension.

CONCLUSION

Overweight and obesity are associated with increased GFR, ERPF, and filtration fraction and a high prevalence of glomerular hyperfiltration in nondiabetic individuals of African descent. The absence of associations between BMI categories and GFR indexed for body surface area raises questions regarding the appropriateness of indexing GFR for body surface area in overweight populations.

Early recognition and prevention of chronic kidney disease

Chronic kidney disease is a common disorder and its prevalence is increasing worldwide. Early diagnosis on the basis of presence of proteinuria or reduced estimated glomerular filtration rate could permit early intervention to reduce the risks of cardiovascular events, kidney failure, and death that are associated with chronic kidney disease. In developed countries, screening for the disorder is most efficient when targeted at high-risk groups including elderly people and those with concomitant illness (such as diabetes, hypertension, or cardiovascular disease) or a family history of chronic kidney disease, although the role of screening in developing countries is not yet clear. Effective strategies are available to slow the progression of chronic kidney disease and reduce cardiovascular risk. Treatment of high blood pressure is recommended for all individuals with, or at risk of, chronic kidney disease. Use of angiotensin-converting-enzyme inhibitors or angiotensin-receptor blockers is preferred for patients with diabetic chronic kidney disease or those with the proteinuric non-diabetic disorder. Glycaemic control can help prevent the onset of early stages of chronic kidney disease in individuals with diabetes. Use of statins and aspirin is beneficial for most patients with chronic kidney disease who are at high cardiovascular risk, although research is needed to ascertain how to best prevent cardiovascular disease in this cohort. Models of care that facilitate delivery of the many complex aspects of treatment simultaneously could enhance management, although effects on clinical outcomes need further assessment. Novel clinical methods to better identify patients at risk of progression to later stages of chronic kidney disease, including kidney failure, are needed to target management to high-risk subgroups.

Urinary albumin excretion, HMW adiponectin, and insulin sensitivity in type 2 diabetic patients undergoing bariatric surgery

BACKGROUND

Microalbuminuria portends an increased risk for renal and cardiovascular diseases in diabetes. In this pilot study, we determined the effect of weight loss induced by different types of bariatric surgery on albuminuria in severely obese type 2 diabetic (T2DM) subjects.

METHODS

Fifteen consecutive T2DM patients (9M/6F, 51+/-14 years, body mass index (BMI) 49+/-9 kg/m2, HbA1c 7.2+/-1.1 percent) undergoing either Roux-en-Y gastric bypass (RYGB; N=9) or other types of bariatric surgery (N=6) underwent determination of urine albumin/creatinine ratio (UACR) and adipokine and insulin sensitivity during a mixed meal tolerance test performed 2 weeks prior to and 6 months following surgery.

RESULTS

Following RYGB, there was a significant decrease in BMI ((-4.74)+/-(-5.05) kg/m2), fasting glucose, cholesterol, and leptin levels. Insulin sensitivity (Matsuda index [12.05+/-3.81, p=0.003]) and high molecular weight (HMW) adiponectin increased significantly along with a significant reduction in UACR (median, 36 mg/g [7-94] vs. 27 mg/g [5.5-42.5], p=0.01). The reduction in UACR following RYGB was inversely correlated with the Matsuda index (r=-0.74), p=0.02) and HMW adiponectin (r=(-0.67), p=0.04). In contrast, despite reduction in BMI ((-4.11)+/-(-4.10) kg/m2) following other types of bariatric surgery (n=6), there was no significant improvement in insulin sensitivity (0.88+/-2.40, p=0.63), UACR, or HMW adiponectin levels.

CONCLUSIONS

RYGB in severely obese DM subjects is associated with a reduction in albuminuria that correlates to the improvement in insulin sensitivity and HMW adiponectin. The data point to a need for larger studies to confirm these findings and evaluate the micro-macrovascular benefits including renal parenchymal benefits of different types of bariatric surgery in T2DM.

Creating research infrastructure and functionality to address chronic kidney disease: the Kidney Research Institute

An expanding proportion of people in the United States and worldwide are affected by kidney disease, leading to a growing concern over the public health implications. Despite the high prevalence and the considerable associated health risks of kidney disease, major gaps in our knowledge base hinder the delivery of optimal medical care to affected individuals. Moreover, research progress that translates into clinical benefit has been slow. For example, over the past 20 years, there has been no successful implementation of a new therapeutic agent specifically designed for the treatment of glomerular diseases, which in part explains why glomerular diseases remain the leading cause of kidney disease in the United States and worldwide. Similarly, the limitations of current approaches to dialysis as treatment of end-stage kidney disease are becoming more apparent, with marginal improvements in risks for hospitalization or mortality over time. Along with recognition of changes in the public health burden of kidney disease, and perception of limited progress in the clinical treatment of kidney disease, a change in kidney disease research is now underway. We are entering a new era in biomedicine emphasizing interdisciplinary and translational research. We here delineate the purpose, mission, and goals, and describe the evolving vision, infrastructure, and research platform of a new Kidney Research Institute, designed to overcome barriers to researching improvements in effective clinical care.

Obesity and chronic kidney disease

This article summarizes the current hypotheses that link visceral obesity and kidney malfunction and provides information on the epidemiology and renal pathology resulting from visceral obesity.

Weight loss and proteinuria: systematic review of clinical trials and comparative cohorts

BACKGROUND

Obesity is a risk factor for the progression of chronic kidney disease (CKD). The impact of weight loss on proteinuria and renal function is less clear. We aimed to determine the effect of intentional weight loss on proteinuria and kidney function.

METHODS

Three bibliographic databases including Medline, Cochrane and SCUPOS as well as reference list of articles were searched. We included randomized and non-randomized controlled trials as well as single-arm trials published in English through May 2009 which examined urinary protein among obese or overweight adults before and after weight loss interventions including dietary restriction, exercise, anti-obesity medications and bariatric surgery. Study characteristics and methodological quality of trials were assessed.

RESULTS

Five hundred twenty-two subjects from five controlled and eight uncontrolled trials were included. Weight loss interventions were associated with decreased proteinuria and microalbuminuria by 1.7 g [95% confidence interval (95% CI), 0.7 to 2.6 g] and 14 mg (95% CI, 11 to 17 mg), respectively (P < 0.05). Meta-regression showed that, independent of decline in mean arterial pressure, each 1 kg weight loss was associated with 110 mg (95% CI, 60 to 160 mg, P < 0.001) decrease in proteinuria and 1.1 mg (95% CI, 0.5 to 2.4 mg, P = 0.011) decrease in microalbuminuria, respectively. The decrease was observed across different designs and methods of weight loss. Only bariatric surgery resulted in a significant decrease in creatinine clearance.

CONCLUSIONS

Weight loss is associated with decreased proteinuria and microalbuminuria. There were no data evaluating the durability of this decrease or the effect of weight loss on CKD progression.

The morbidity and mortality associated with overweight and obesity in adulthood: a systematic review

BACKGROUND

Overweight and obesity are generally thought to elevate morbidity and mortality. New data call this supposed association into question.

METHODS

The Cochrane, Pubmed, and other databases were systematically searched for a combination of relevant terms and subject headings. Meta-analyses and cohort studies based on the German population were evaluated for possible associations between overweight/ obesity and adult morbidity and mortality. Case-control and cross-sectional studies were excluded.

RESULTS

A total of 27 meta-analyses and 15 cohort studies were evaluated. The overall mortality of overweight persons (body mass index [BMI] 25-29.9 kg/m(2)) is no higher than that of persons of normal weight (BMI 18.5-24.9 kg/m(2)), but their mortality from individual diseases is elevated, diminished or unchanged, depending on the particular disease. The overall morbidity is unknown. Both obesity (BMI >30 kg/m(2)) and overweight are associated with increased disease-specific morbidity for some diseases, but decreased or unchanged for others. In general, obesity confers a higher risk than overweight. Morbidity and mortality are markedly influenced by the patient's age, sex, ethnic origin, and social status. The external validity of the comparative predictive performance (c-statistic) of BMI, waist circumference, and ratio of waist to hip circumference cannot be determined from the available analyses.

CONCLUSION

The prevailing notion that overweight increases morbidity and mortality, as compared to so-called normal weight, is in need of further specification. Obesity, however, is indeed associated with an elevated risk for most of the diseases studied.

The farnesoid X receptor modulates renal lipid metabolism and diet-induced renal inflammation, fibrosis, and proteinuria

Diet-induced obesity is associated with proteinuria and glomerular disease in humans and rodents. We have shown that in mice fed a high-fat diet, increased renal expression of the transcriptional factor sterol-regulatory element binding protein-1 (SREBP-1) plays a critical role in renal lipid accumulation and increases the activity of proinflammatory cytokines and profibrotic growth factors. In the current study, we have determined a key role of the farnesoid X receptor (FXR) in modulating renal SREBP-1 activity, glomerular lesions, and proteinuria. We found that feeding a Western-style diet to DBA/2J mice results in proteinuria, podocyte loss, mesangial expansion, renal lipid accumulation, and increased expression of proinflammatory factors, oxidative stress, and profibrotic growth factors. Treatment of these mice with the highly selective and potent FXR-activating ligand 6-alpha-ethyl-chenodeoxycholic acid (INT-747) ameliorates triglyceride accumulation by modulating fatty acid synthesis and oxidation, improves proteinuria, prevents podocyte loss, mesangial expansion, accumulation of extracellular matrix proteins, and increased expression of profibrotic growth factors and fibrosis markers, and modulates inflammation and oxidative stress. Our results therefore indicate that FXR activation could represent an effective therapy for treatment of abnormal renal lipid metabolism with associated inflammation, oxidative stress, and kidney pathology in patients affected by obesity.

Weight loss interventions in chronic kidney disease: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

Obesity is an independent risk factor for development and progression of chronic kidney disease (CKD). We conducted a systematic review to assess the benefits of intentional weight loss in patients with non-dialysis-dependent CKD and glomerular hyperfiltration.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We searched MEDLINE, SCOPUS, and conference proceedings for randomized, controlled trials and observational studies that examined various surgical and nonsurgical interventions (diet, exercise, and/or antiobesity agents) in adult patients with CKD. Results were summarized using random-effects model.

RESULTS

Thirteen studies were included. In patients with CKD, body mass index (BMI) decreased significantly (weighted mean difference [WMD] -3.67 kg/m(2); 95% confidence interval [CI] -6.56 to -0.78) at the end of the study period with nonsurgical interventions. This was associated with a significant decrease in proteinuria (WMD -1.31 g/24 h; 95% CI -2.11 to -0.51) and systolic BP with no further decrease in GFR during a mean follow-up of 7.4 mo. In morbidly obese individuals (BMI >40 kg/m(2)) with glomerular hyperfiltration (GFR >125 ml/min), surgical interventions decreased BMI, which resulted in a decrease in GFR (WMD -25.56 ml/min; 95% CI -36.23 to -14.89), albuminuria, and systolic BP.

CONCLUSIONS

In smaller, short-duration studies in patients with CKD, nonsurgical weight loss interventions reduce proteinuria and BP and seem to prevent further decline in renal function. In morbidly obese individuals with glomerular hyperfiltration, surgical interventions normalize GFR and reduce BP and microalbuminuria. Larger, long-term studies to analyze renal outcomes such as development of ESRD are needed.