Does treating obesity stabilize chronic kidney disease?

The risk of kidney dysfunction in metabolically healthy/unhealthy population with normal weight or overweight/obesity: a systematic review and meta-analysis

BACKGROUND

Chronic kidney disease (CKD) is a major global health concern with increasing prevalence and associated complications. Obesity and obesity-related metabolic disorders have been linked to chronic kidney disease (CKD), although the evidence is still inconsistent. To investigate the relationship between different obesity phenotypes and the risk of CKD, we conducted a systematic review and meta-analysis.

METHOD

We conducted a comprehensive search of databases for all relevant studies up to February 2024, without imposing a specific start date, for observational studies assessing the relationship between obesity phenotypes and incident kidney dysfunction. We used fixed and random effects models for the meta-analysis, subgroup analyses were carried out to explore heterogeneity, and Egger's and Begg's tests were used to assess publication bias.

RESULT

This meta-analysis included 13 eligible observational studies with 492,829 participants. Pooling the studies regardless of the effect measure showed that individuals with metabolically unhealthy normal weight (MUNW) (ES = 1.58, 95% CI = 1.43-1.76), metabolically healthy obese (MHO) (ES = 1.20, 95% CI = 1.06-1.34), and metabolically unhealthy obese (MUO) (ES = 1.90, 95% CI = 1.63-2.20) phenotypes had a significantly increased risk for kidney dysfunction (KD) events. On the other hand, MUOW individuals did not significantly correlate with risk of CKD (ES = 1.63, 95% CI = 0.97-2.23) compared to the MHNW phenotype.

CONCLUSION

Healthy overweight and obese individuals had higher risk for the incident KD events; refuting the notion that metabolically healthy overweight and obese phenotypes are benign conditions.

LEVEL OF EVIDENCE

III Evidence obtained from well-designed cohort or cross-sectional studies.

Metabolic Phenotypes and Chronic Kidney Disease: A Cross-Sectional Assessment of Patients from a Large Federally Qualified Health Center

The purpose of this study is to determine if renal function varies by metabolic phenotype. A total of 9599 patients from a large Federally Qualified Health Center (FQHC) were included in the analysis. Metabolic health was classified as the absence of metabolic abnormalities defined by the National Cholesterol Education Program Adult Treatment Panel III criteria, excluding waist circumference. Obesity was defined as body mass index >30 kg/m2 and renal health as an estimated glomerular filtration rate (eGFR) >60 mL/min/1.73 m2. Linear and logistic regressions were used to analyze the data. The metabolically healthy overweight (MHO) phenotype had the highest eGFR (104.86 ± 28.76 mL/min/1.72 m2) and lowest unadjusted odds of chronic kidney disease (CKD) (OR = 0.46, 95%CI = 0.168, 1.267, p = 0.133), while the metabolically unhealthy normal weight (MUN) phenotype demonstrated the lowest eGFR (91.34 ± 33.28 mL/min/1.72 m2) and the highest unadjusted odds of CKD (OR = 3.63, p < 0.0001). After controlling for age, sex, and smoking status, the metabolically unhealthy obese (MUO) (OR = 1.80, 95%CI = 1.08, 3.00, p = 0.024) was the only phenotype with significantly higher odds of CKD as compared to the reference. We demonstrate that the metabolically unhealthy phenotypes have the highest odds of CKD compared to metabolically healthy individuals.

Metabolic phenotypes of obese, overweight, and normal weight individuals and risk of chronic kidney disease: a systematic review and meta-analysis

OBJECTIVE

Chronic kidney disease (CKD) risk is inconsistent in the normal-weight, overweight, and obese individuals due to the heterogeneity of metabolic status. This meta-analysis aimed to examine the combined effects of body mass index (BMI) and metabolic status on CKD risk.

MATERIALS AND METHODS

The MEDLINE, EMBASE, and Web of Knowledge databases were systematically searched up to March 2019 to identify all eligible studies investigating the CKD risk (defined as GFR < 60 mL/min per 1.73 m2 and/or microalbuminuria or proteinuria) associated with the body size phenotypes which are known as metabolically unhealthy normal-weight (MUNW), metabolically healthy overweight (MHOW), metabolically unhealthy overweight, metabolically healthy obese (MHO) and metabolically unhealthy obese (MUHO). The classification of subjects in included studies as metabolically unhealthy was based on the presence of three components of metabolic syndrome. BMI categorization was based on the criteria of included studies. The risk estimates and 95% confidence intervals (CIs) were extracted and pooled using random effects analysis.

RESULTS

A total of 9 prospective cohort studies with 128773 participants and 4797 incident cases were included in the meta-analysis. Compared with healthy normal-weight individuals as reference, MUNW and MHO subjects showed an increased risk for CKD events with a pooled RR of 1.58 (95% CI = 1.28-1.96) in MUNW and 1.55 (95% CI = 1.34-1.79) in MHO persons. Also, MHOW was at increased risk for CKD (RR = 1.34, 95% CI = 1.20-1.51). MUHO individuals were at the highest risk for the development of CKD (RR = 2.13, 95% CI = 1.66-2.72).

CONCLUSIONS

Individuals with metabolic abnormality, although at normal-weight, have an increased risk for CKD. Healthy overweight and obese individuals had higher risk; refuting the notion that metabolically healthy overweight and obese phenotypes are benign conditions.

Bariatric Surgery Modulates Urinary Levels of MicroRNAs Involved in the Regulation of Renal Function

Background: Obesity and diabetes cause chronic kidney disease with a common pathophysiology that is characterized by the accumulation of collagen in the extracellular matrix. Recent evidence has implicated the epithelial-to-mesenchymal transition (EMT) as a key step in this pathology with regulation by microRNAs. Weight loss leads to improvements in renal function; therefore, this study hypothesized that bariatric-surgery aided weight loss would lead to changes in urinary microRNAs involved in the regulation of renal function. Materials and methods: Twenty-four bariatric patients undergoing Roux-en-Y gastric bypass and sleeve gastrectomy donated urine pre-operatively and at 2-6 months and 1-2 years post-operatively. Urine samples were also obtained from 10 healthy weight and 7 morbidly obese non-surgical controls. Expression levels of kidney microRNAs were assessed in urine and the function of microRNAs was assessed through the in vitro transfection of HK-2 cells, a kidney proximal tubule cell line. Results: Levels of miR 192, miR 200a, and miR 200b were upregulated in urine following bariatric surgery. This increase was consistent across surgical type and diabetes status and was maintained and enhanced with time. Bariatric surgery alters urinary miR 192 expression from levels seen in morbidly obese patients to levels seen in healthy weight control patients. In mechanistic studies, the transfection of miR 192 in HK-2 cells increased miR 200a expression and decreased ZEB2, a key transcriptional promoter of kidney fibrosis. Conclusions: Bariatric surgery increased miR 192 and miR 200 urinary levels, key anti-fibrotic microRNAs that could contribute to a renal-protective mechanism and may be of value as urinary biomarkers following surgery. These findings suggest that urinary microRNAs may represent potential novel biomarkers for obesity-associated renal function.

Gastric Bypass in Chronic Renal Failure and Renal Transplant

BACKGROUND

Morbid obesity has reached epidemic proportions in developed nations worldwide, causing considerable mortality and increased healthcare expenditures. The use of gastric bypass surgery to achieve weight loss in morbidly obese patients with chronic renal failure (CRF) and postrenal transplant patients has not been studied adequately.

METHODS

Forty-one patients with different stages of CRF (25 already receiving dialysis) underwent a gastric bypass (GBP), and an additional 10 patients underwent a GBP after becoming morbidly obese after transplantation.

RESULTS

Of the 41 patients with CRF, 5 stabilized or resolved their kidney disease and 9 underwent successful transplantation. These patients had a loss of 68% excess body mass index (BMI) by 12 months after GBP. Of the 10 patients with GBP after transplant, the mean loss of excess BMI was 70.5%. There were no in-hospital or 30-day mortalities, but 8 of the 51 patients died from 112 to 2869 days postoperatively, 7 from cardiac or vascular events and 1 from an automobile accident. This compares with an approximate 10% mortality per year for patients receiving dialysis. Comorbid conditions associated with morbid obesity improved in all patients and permitted eligibility for transplantation.

CONCLUSIONS

GBP for massive weight reduction in morbidly obese renal failure and transplant patients leads to a reduction in comorbid conditions that are associated with an increased risk for cardiovascular deaths. There was no operative mortality in this series, and all but 1 death were related to previously existing disease of the cardiovascular system.

Medical Weight Loss Treatment Options in Obese Solid-Organ Transplant Candidates

With the increasing incidence of obesity in our country, the rate of obesity seen in organ transplant candidates is also rising. Accurate descriptions and measures of weight and degree of obesity vary between organ systems. Weight loss can be achieved in some patients while they wait for the transplant surgery. Weight reduction in transplant candidates involves a team approach, with a program of education and support, including medical nutrition therapy, physical therapy, and psychological support. The safety and applicability of weight loss medications to assist with pretransplant weight loss is also not well understood. It is not yet well known if weight loss before transplantation will improve posttransplant outcomes. Many questions regarding the treatment of obesity in transplant candidates remain unanswered.

Is Bariatric Surgery an Effective Treatment for Type II Diabetic Kidney Disease?

Type II diabetic kidney disease is devastating to patients and society alike. This review will evaluate bariatric surgery as a treatment for diabetic kidney disease primarily through its ability to induce and maintain regression of type II diabetes. The review begins by outlining the global challenge of diabetic kidney disease, its link to obesity, and the comparative benefits of bariatric surgery on weight and type II diabetes. It then surveys comprehensively the relevant literature, which reports that although bariatric surgery is associated with reductions in albuminuria, its effect on harder clinical end points like progression of diabetic kidney disease is not known. The review also includes a critical assessment of the risks and costs of bariatric surgery and concludes by acknowledging the major knowledge gaps in the field and providing research strategies to overcome them. Until these knowledge gaps are filled, clinicians will be forced to rely on their own subjective judgment in determining the benefit-risk ratio of bariatric surgery for patients with diabetic kidney disease.

Obesity-induced changes in kidney mitochondria and endoplasmic reticulum in the presence or absence of leptin

We investigated obesity-induced changes in kidney lipid accumulation, mitochondrial function, and endoplasmic reticulum (ER) stress in the absence of hypertension, and the potential role of leptin in modulating these changes. We compared two normotensive genetic mouse models of obesity, leptin-deficient ob/ob mice and hyperleptinemic melanocortin-4 receptor-deficient mice (LoxTB MC4R-/-), with their respective lean controls. Compared with controls, ob/ob and LoxTB MC4R-/- mice exhibit significant albuminuria, increased creatinine clearance, and high renal triglyceride content. Renal ATP levels were decreased in both obesity models, and mitochondria isolated from both models showed alterations that would lower mitochondrial ATP production. Mitochondria from hyperleptinemic LoxTB MC4R-/- mice kidneys respired NADH-generating substrates (including palmitate) at lower rates due to an apparent decrease in complex I activity, and these mitochondria showed oxidative damage. Kidney mitochondria of leptin-deficient ob/ob mice showed normal rates of respiration with no evidence of oxidative damage, but electron transfer was partially uncoupled from ATP synthesis. A fourfold induction of C/EBP homologous protein (CHOP) expression indicated induction of ER stress in kidneys of hyperleptinemic LoxTB MC4R-/- mice. In contrast, ER stress was not induced in kidneys of leptin-deficient ob/ob mice. Our findings show that obesity, in the absence of hypertension, is associated with renal dysfunction in mice but not with major renal injury. Alterations to mitochondria that lower cellular ATP levels may be involved in obesity-induced renal injury. The type and severity of mitochondrial and ER dysfunction differs depending upon the presence or absence of leptin.

Do Obese Individuals With Hypertension Have More Difficult-to-Control Blood Pressure and End Organ Damage Than Their Nonobese Counterparts?

The authors assessed whether individuals with elevated body mass index (BMI) and hypertension had more difficult-to-control blood pressure (BP) and more evidence of end organ damage using data collected prospectively over 11 years from a secondary care hypertension clinic. A total of 1114 individuals were divided by BMI criteria into normal (n=207), overweight (n=440), and obese (n=467). Mean daytime, nighttime, and 24-hour systolic BP and diastolic BP were similar in all groups. There was less nocturnal dip in obese compared with overweight groups (P=.025). Individuals with a normal BMI were taking fewer antihypertensive medications than those in the obese group (P=.01). Individuals classified as obese had a higher left ventricular mass index than those with a normal BMI (female, P=.028; male, P<.001); this relationship remained after multivariate linear regression. Obese individuals with hypertension required more medication to achieve similar mean ambulatory BP values, had less nocturnal dip in BP, and had a higher prevalence of left ventricular hypertrophy. As such, obese patients are at potentially increased risk of cardiovascular events.

Long-Term Normal Renal Function after Drastic Weight Reduction in Patients with Obesity-Related Glomerulopathy

AIMS

No long-term studies of renal function evolution in morbidly obese (MO) patients after weight loss are available. The aim of our work was to ascertain the long-term influence of drastic weight reduction on renal function in MO patients with obesity-related glomerular lesions.

METHODS

92 MO patients with normal renal function and biopsy evidence of mild obesity-related glomerulopathy underwent bariatric surgery (BS) and subsequent drastic weight loss. A long-term prospective follow-up (mean duration: 76 ± 42 months) was carried out. Basal renal biopsies and basal and long-term metabolic and renal function studies were performed in all cases. Linear mixed models were applied.

RESULTS

Blood pressure dropped early after BS and remained stable thereafter. Creatinine clearance and BMI fell in the first 2 years, rose slightly after 5 years and then remained stable. Serum creatinine and albuminuria decreased throughout the follow-up period. Renal function and albuminuria evolution showed non-significant differences in relation to the number of glomerular lesions.

CONCLUSIONS

Drastic weight loss in BS-treated MO patients with pre-surgical normal renal function and mild obesity-related glomerular lesions is associated with short- and long-term maintenance of normal renal function and improvement in both arterial hypertension and albuminuria.

Bariatric surgery in patients with reduced kidney function: an analysis of short-term outcomes

BACKGROUND

With rates of obesity among patients with chronic kidney disease (CKD) mirroring that of the general population, there is growing interest in offering bariatric surgery to these patients. We sought to determine the safety of bariatric surgery in this patient population.

METHODS

Patients who underwent selected laparoscopic bariatric procedures between 2005 and 2011. Estimated glomerular filtration rate (eGFR) was calculated and divided into stages of CKD. Procedures included Roux-en-Y gastric bypass (RYGB), laparoscopic adjustable gastric band (LAGB), and laparoscopic sleeve gastrectomy (SG). Univariable analysis and multivariable adjustment was used to compare complication rates across stages of eGFR.

RESULTS

A total of 64,589 patients were included: 64.5% underwent RYGB, 29.8% LAGB, and 5.7% SG. A total of 61.7% of patients had normal eGFR (Stage 1), 32.0% were stage 2, 5.3% were stage 3, and 1.0% were stage 4/5. After adjusting for relevant patient characteristics, there was a trend toward increasing complications from stage 1 to stage 4/5 CKD among RYGB, LAGB, and SG groups, but none were statistically significant. Similarly, major complications generally increased across stages of CKD for each procedure, but was only significant for RYGB comparing stage 3 to stage 1 (OR 1.22; 95% CI: 1.01-1.47; P = .042) and risk difference .96% (95% CI: .03-1.96). Considering only stage 4/5 CKD, overall (P = .114) and major complications (P = .032) were highest in the RYGB group, followed by SG and LAGB.

CONCLUSION

More advanced stages of CKD do not appear to be statistically associated with an increased risk of 30-day postoperative complications.

A new dietary strategy for long-term treatment of the metabolic syndrome is compared with the American Heart Association (AHA) guidelines: the MEtabolic Syndrome REduction in NAvarra (RESMENA) project

The long-term effects of dietary strategies designed to combat the metabolic syndrome (MetS) remain unknown. The present study evaluated the effectiveness of a new dietary strategy based on macronutrient distribution, antioxidant capacity and meal frequency (MEtabolic Syndrome REduction in NAvarra (RESMENA) diet) for the treatment of the MetS when compared with the American Heart Association guidelines, used as Control. Subjects with the MetS (fifty-two men and forty-one women, age 49 (se 1) years, BMI 36·11 (se 0·5) kg/m²) were randomly assigned to one of two dietary groups. After a 2-month nutritional-learning intervention period, during which a nutritional assessment was made for the participants every 15 d, a 4-month self-control period began. No significant differences were found between the groups concerning anthropometry, but only the RESMENA group exhibited a significant decrease in body weight ( - 1·7%; P= 0·018), BMI ( - 1·7%; P= 0·019), waist circumference ( - 1·8%; P= 0·021), waist:hip ratio ( - 1·4%; P= 0·035) and android fat mass ( - 6·9%; P= 0·008). The RESMENA group exhibited a significant decrease in alanine aminotransferase and aspartate aminotransferase (AST) concentrations ( - 26·8%; P= 0·008 and - 14·0%; P= 0·018, respectively), while the Control group exhibited a significant increase in glucose (7·9%; P= 0·011), AST (11·3%; P= 0·045) and uric acid (9·0%; P< 0·001) concentrations. LDL-cholesterol (LDL-C) concentrations were increased (Control group: 34·4%; P< 0·001 and RESMENA group: 33·8%; P< 0·001), but interestingly so were the LDL-C:apoB ratio (Control group: 28·7%; P< 0·001, RESMENA group: 17·1%; P= 0·009) and HDL-cholesterol concentrations (Control group: 21·1%; P< 0·001, RESMENA group: 8·7; P= 0·001). Fibre was the dietary component that most contributed to the improvement of anthropometry, while body-weight loss explained changes in some biochemical markers. In conclusion, the RESMENA diet is a good long-term dietary treatment for the MetS.

Obesity-related cardiorenal disease: the benefits of bariatric surgery

The inexorable increase in the prevalence of obesity is a global health concern, which will result in a concomitant escalation in health-care costs. Obesity-related metabolic syndrome affects approximately 25% of adults and is associated with cardiovascular and renal disease. The heart and kidneys are physiologically interdependent, and the pathological effects of obesity can lead to cardiorenal syndrome and, ultimately, kidney and heart failure. Weight loss can prevent or ameliorate obesity-related cardiorenal syndrome, but long-term maintenance of a healthy weight has been difficult to achieve through lifestyle changes or pharmacotherapy. Bariatric surgery offers both sustained weight loss and favourable metabolic changes, including dramatic improvements in glycaemic control and symptoms of type 2 diabetes mellitus. Procedures such as Roux-en-Y gastric bypass offer immediate multisystemic benefits, including bile flow alteration, reduced gastric size, anatomical gut rearrangement and altered flow of nutrients, vagal manipulation and enteric hormone modulation. In patients with cardiorenal syndrome, bariatric surgery also offers renoprotection and cardioprotection, and attenuates both kidney and heart failure by improving organ perfusion and reversing metabolic dysfunction. However, further research is required to understand how bariatric surgery acts on the cardiorenal axis, and its pioneering role in novel treatments and interventions for cardiorenal disease.

The link between the renin-angiotensin-aldosterone system and renal injury in obesity and the metabolic syndrome

Obesity is a risk factor for type 2 diabetes mellitus (DM) and is associated with chronic kidney disease. Activation of the renin-angiotensin-aldosterone system (RAAS) is common in obesity. The RAAS is an important mediator of hypertension. Mechanisms involved in activation of the RAAS in obesity include sympathetic stimulation, synthesis of adipokines in the RAAS by visceral fat, and hemodynamic alterations. The RAAS is known for its role in regulating blood pressure and fluid and electrolyte homeostasis. The role of local/tissue RAAS in specific tissues has been a focus of research. Urinary angiotensinogen (UAGT) provides a specific index of the intrarenal RAAS. Investigators have demonstrated that sex steroids can modulate the expression and activity of the different components of the intrarenal RAAS and other tissues. Our data suggest that obese women without DM and hypertension have significantly higher levels of UAGT than their male counterparts. These differences existed without any background difference in the ratio of microalbumin to creatinine in the urine or the estimated glomerular filtration rate, raising a question about the importance of baseline gender differences in the endogenous RAAS in the clinical spectrum of cardiovascular diseases and the potential utility of UAGT as a marker of the intrarenal RAAS. Animal studies have demonstrated that modifying the amount of angiotensin, the biologically active component of the RAAS, directly influences body weight and adiposity. This article reviews the role of the RAAS in renal injury seen in obesity and the metabolic syndrome.

Impact of bariatric surgery on comorbidities

Published data show that bariatric surgery not only leads to significant and sustained weight loss but also resolves or improves multiple comorbidities associated with morbid obesity. Evidence suggests that the earlier the intervention the better the resolution of comorbidities. Patients with metabolic syndrome and comorbidities associated with morbid obesity should be promptly referred for consideration for bariatric surgery earlier in the disease process.

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.

Urinary catalytic iron in obesity

INTRODUCTION

Obesity precedes the development of many cardiovascular disease risk factors, including type 2 diabetes mellitus (DM), hypertension, and chronic kidney disease. Catalytic iron, which has been associated with these chronic diseases, may be one of the links between obesity and these multifactorial diverse disorders.

OBJECTIVE

We investigated whether urinary catalytic iron is increased in obese individuals without DM and overt kidney disease.

STUDY DESIGN

We measured urinary catalytic iron using established methods in 200 randomly selected individuals without DM [100 who were obese (body mass index ≥30 kg/m(2)) and 100 who were nonobese (body mass index ≤27)]. Participants were selected from an outpatient clinic and community setting and were part of an ongoing cross-sectional study of obesity in individuals between the ages of 18 and 70 years.

RESULTS

There was a significant difference in mean (95% CI) urinary catalytic iron excretion between the obese participants and the nonobese participants, 463 (343-582) nmol/mg [52.3 (38.8-65.8) nmol/μmol] vs 197 (141-253) nmol/mg [22.3 (15.9-28.6) nmol/μmol]; P < 0.001. The significant predictors of increased urinary catalytic iron were obesity (P = 0.001) and waist-to-hip ratio (P = 0.03).

CONCLUSIONS

Our study results demonstrate that obesity and waist-to-hip ratio are associated with increased urinary catalytic iron, which may be a useful marker of oxidative stress. Additional studies are needed to determine the role of catalytic iron in increased cardiovascular disease and chronic kidney disease associated with obesity.

Metabolic, renal, and nutritional consequences of bariatric surgery: implications for the clinician

Management of obesity-associated comorbidities costs about $60 billion/year, about 5% of total US healthcare expenditure. Bariatric surgery is the only proven effective weight loss therapy for severely obese patients with a BMI > or =35 kg/m2. Bariatric surgery produces long-term weight loss, improves quality of life, and reduces the number of sick days and medication costs. Surgery has a profound effect on the metabolic milieu and nutritional status from the first few days after surgery, even before significant weight loss has been achieved. Metabolic effects of bariatric surgery reduce obesity-related comorbidities like type 2 diabetes, hypertension, metabolic syndrome, and cardiovascular disease risk. Improvement in renal function is seen, but adverse effects like oxalate nephropathy can lead to chronic kidney disease or end-stage renal disease (CKD/ESRD). Surgery can also lead to micronutrient deficiencies, making dietary supplementation necessary. Reduction in insulin resistance and hypertension after surgery makes medication adjustment imperative. Improvement in comorbidities and nutritional deficiencies after bariatric surgery has important clinical implications.

Bariatric surgery among kidney transplant candidates and recipients: analysis of the United States renal data system and literature review

BACKGROUND

Limited data exist on the safety and efficacy of bariatric surgery (BS) in patients with kidney failure.

METHODS

We examined Medicare billing claims within USRDS registry data (1991-2004) to identify BS cases among renal allograft candidates and recipients.

RESULTS

Of 188 BS cases, 72 were performed pre-listing, 29 on the waitlist, and 87 post-transplant. Roux-en-Y gastric bypass was the most common procedure. Thirty-day mortality after BS performed on the waitlist and post-transplant was 3.5%, and one transplant recipient lost their graft within 30 days after BS. BMI data were available for a subset and suggested median excess body weight loss of 31%-61%. Comparison to published clinical trials of BS in populations without kidney disease indicates comparable weight loss but higher post-BS mortality in the USRDS sample.

CONCLUSIONS

Given the substantial contributions of obesity to excess morbidity and mortality, BS warrants prospective study as a strategy for improving outcomes before and after kidney transplantation.

High plasma norepinephrine levels associated with beta2-adrenoceptor polymorphisms predict future renal damage in nonobese normotensive individuals

Renal injury is common in obesity and hypertension. In the present study, we examined relationships between renal function alterations, plasma norepinephrine (NE), and beta2-adrenoceptor polymorphisms in a longitudinal design over 5 years. In 219 nonobese, normotensive men with entry-normal renal function, we measured serum blood urea nitrogen (BUN), creatinine, creatinine clearance, plasma NE, homeostasis model assessment of insulin resistance (HOMA-IR), body mass index (BMI), total body fat mass, and blood pressure (BP) annually for 5 years. beta2 (Arg16Gly, Gln27Glu)-adrenoceptor polymorphisms were determined. The subjects were stable in body weight and BP (<10%) for 5 years. High plasma NE was defined as > or =mean+1 SD at entry. Thirty-seven subjects had entry-high plasma NE and 182 were entry-normal. Entry-high plasma NE subjects had significantly greater total body fat mass and plasma NE and significantly lower creatinine clearance at entry and throughout the study. Increases in BMI, fat mass, BP, plasma NE, BUN, and creatinine, as well as the reduction in creatinine clearance in the 5 years, were significantly greater in entry-high NE subjects. These subjects had significantly higher frequencies of the Gly16 allele of beta2-adrenoceptor polymorphisms. Throughout the study, subjects carrying the Gly16 allele had higher plasma NE, HOMA-IR, and fat mass, and significantly greater reductions in creatinine clearance. Plasma NE at entry was a determinant variable for changes in BUN, creatinine, and creatinine clearance over the 5-year period in multiple regression analysis. In conclusion, high plasma NE at entry, associated with the Gly16 allele of the beta2-adrenoceptor polymorphisms, predict renal function deterioration (seen in elevations of BUN and creatinine and reduction of creatinine clearance) over a 5-year period accompanying further heightened sympathetic nerve activity and deterioration of insulin resistance.

Hypertension and impaired renal function accompany juvenile obesity: the effect of prenatal diet

Obesity has been suggested to have a detrimental impact on kidney structure and function, leading to focal glomerulosclerosis and hypertension. It is also associated with hyperleptinemia and elevated renal sympathetic nerve activity. Prenatal undernutrition promotes postnatal obesity, hypertension, and an altered renal structure and function. In this study, we examined the effects of prenatal nutrient restriction and juvenile obesity in sheep. We found that juvenile obesity led to chronic hyperleptinemia and reduced renal function as assessed by nuclear scintigraphy. Additional factors include hypertension, glomerulosclerosis, and increased kidney apoptosis. Prenatal undernutrition, synchronous with early kidney development, coupled postnatally with juvenile obesity had no effect on systemic pathophysiological sequalae associated with obesity per se. Hypertension, hyperleptinemia, and poor renal function were all observed in this group. All indices of renal pathology such as increased expression of proinflammatory cytokines, angiotensin II, glucocorticoid receptors, and increased apoptosis and glomerulosclerosis were entirely absent in obese prenatally undernourished offspring. Our data indicate that juvenile obesity per se leads to systemic hypertension and renal structural and functional pathology. Prenatal undernutrition effectively abolishes any renal histopathology associated with juvenile obesity.

Uric acid, the metabolic syndrome, and renal disease

Metabolic syndrome, characterized by truncal obesity, hypertriglyceridemia, elevated BP, and insulin resistance, is recognized increasingly as a major risk factor for kidney disease and also is a common feature of patients who are on dialysis. One feature that is common to patients with metabolic syndrome is an elevated uric acid. Although often considered to be secondary to hyperinsulinemia, recent evidence supports a primary role for uric acid in mediating this syndrome. Specifically, fructose, which rapidly can cause metabolic syndrome in rats, also raises uric acid, and lowering uric acid in fructose-fed rats prevents features of the metabolic syndrome. Uric acid also can accelerate renal disease in experimental animals and epidemiologically is associated with progressive renal disease in humans. It is proposed that fructose- and purine-rich foods that have in common the raising of uric acid may have a role in the epidemic of metabolic syndrome and renal disease that is occurring throughout the world.

Bariatric surgery for morbid obesity: risks and benefits in chronic kidney disease patients

Obesity is one of the most preventable causes of morbidity and mortality of the 21st century. Chronic kidney disease (CKD) has been a largely overlooked consequence of obesity; however, accumulating evidence elucidates the association. Obesity is at the core, promoting a cascade of secondary pathologies including diabetes, dyslipidemia, inflammation, hypertension, and the metabolic syndrome; these comorbidities constitute great risk for CKD. With the diagnosis of CKD, there is an increased threat of cardiovascular disease and the attendant increase in morbidity and mortality rates. Substantial weight loss in the obese population can be effectively achieved and maintained through bariatric surgery, which confers major health benefits by producing resolution or improvement of obesity-related comorbidities. This surgical procedure presents an early hazard of acute on chronic kidney failure, which is offset by a potential improvement in the risk of CKD progression with anticipated improvement in hypertension, diabetes, and CKD risk factors. Future research is needed to describe the clinical course and risks and benefits of bariatric surgery in the CKD population.

A low-carbohydrate diet may prevent end-stage renal failure in type 2 diabetes. A case report

An obese patient with type 2 diabetes whose diet was changed from the recommended high-carbohydrate, low-fat type to a low-carbohydrate diet showed a significant reduction in bodyweight, improved glycemic control and a reversal of a six year long decline of renal function. The reversal of the renal function was likely caused by both improved glycemic control and elimination of the patient's obesity. Insulin treatment in type 2 diabetes patients usually leads to weight increase which may cause further injury to the kidney. Although other unknown metabolic mechanisms cannot be excluded, it is likely that the obesity caused by the combination of high-carbohydrate diet and insulin in this case contributed to the patient's deteriorating kidney function. In such patients, where control of bodyweight and hyperglycemia is vital, a trial with a low-carbohydrate diet may be appropriate to avoid the risk of adding obesity-associated renal failure to already failing kidneys.

Update on obesity surgery

The prevalence of obesity in the United States has reached epidemic proportions. With more than 30 million Americans clinically obese, the younger population has also been affected. Surgical therapy should be offered to the severely obese patient who is refractory to nonsurgical therapy, as established by the 1991 NIH Consensus Conference on Gastrointestinal Surgery for Severe Obesity. Surgery is currently the most effective therapy for weight loss. It is far more effective than any other treatment modality, both in terms of the amount of weight loss and in terms of durability in maintaining weight loss.

Communicating the ocular and systemic complications of obesity to patients

BACKGROUND

Obesity has become a growing worldwide epidemic that is associated with serious medical complications. Many clinicians and patients are aware of the systemic complications of obesity, but there are few providers and patients who are aware of the ocular manifestations of obesity.

METHODS

A review of the current medical literature was performed. Ocular and systemic manifestations associated with obesity are described, and a methodology for educating the optometric patient is presented.

RESULTS

There is significant morbidity and mortality associated with obesity, which is causing serious consequences to patients and an enormous economic strain on the health care system. Optometrists have a tremendous opportunity and obligation to educate their patients on the potential sight-threatening complications of obesity and encourage them to decrease their caloric intake and increase their physical activity to help alleviate this individual and collective burden.

CONCLUSIONS

Optometrists have a duty to educate and counsel their overweight and obese patients on the devastating ocular complications that could manifest as a result of obesity.