Kidney outcomes three years after bariatric surgery in severely obese adolescents. Kidney Int. 2017;91:451-458. [PMID: 27914704 DOI: 10.1016/j.kint.2016.09.031]

Chronic kidney disease combined with metabolic syndrome is a non-negligible risk factor

Metabolic syndrome (MetS) is a group of conditions characterized by hypertension (HTN), hyperglycaemia or insulin resistance (IR), hyperlipidaemia, and abdominal obesity. MetS is associated with a high incidence of cardiovascular events and mortality and is an independent risk factor for chronic kidney disease (CKD). MetS can cause CKD or accelerate the progression of kidney disease. Recent studies have found that MetS and kidney disease have a cause-and-effect relationship. Patients with CKD, those undergoing kidney transplantation, or kidney donors have a significantly higher risk of developing MetS than normal people. The present study reviewed the possible mechanisms of MetS in patients with CKD, including the disorders of glucose and fat metabolism after kidney injury, IR, HTN and the administration of glucocorticoid and calcineurin inhibitors. In addition, this study reviewed the effect of MetS in patients with CKD on important target organs such as the kidney, heart, brain and blood vessels, and the treatment and prevention of CKD combined with MetS. The study aims to provide strategies for the diagnosis, treatment and prevention of CKD in patients with MetS.

Cardiometabolic comorbidities and complications of obesity and chronic kidney disease (CKD)

Obesity and chronic kidney disease are two ongoing progressive clinical pandemics of major public health and clinical care significance. Because of their growing prevalence, chronic indolent course and consequent complications both these conditions place significant burden on the health care delivery system especially in developed countries like the United States. Beyond the chance coexistence of both of these conditions in the same patient based on high prevalence it is now apparent that obesity is associated with and likely has a direct causal role in the onset, progression and severity of chronic kidney disease. The causes and underlying pathophysiology of this are myriad, complicated and multi-faceted. In this review, continuing the theme of this special edition of the journal on " The Cross roads between Endocrinology and Nephrology" we review the epidemiology of obesity related chronic kidney disease (ORCKD), and its various underlying causes and pathophysiology. In addition, we delve into the consequent comorbidities and complications associated with ORCKD with particular emphasis on the cardio metabolic consequences and then review the current body of evidence for available strategies for chronic kidney disease modulation in ORCKD as well as the potential unique role of weight reduction and management strategies in its improvement and risk reduction.

Microvascular complications of obesity and diabetes-Role of bariatric surgery

Bariatric surgery in people with obesity can lead to long-term remission of type 2 diabetes mellitus (T2DM) and a reduction in the incidence of macrovascular complications. The impact of bariatric surgery on microvascular complications is less clear. In this narrative review, we sought to evaluate the effect of bariatric surgery on microvascular complications in patients with and without diabetes. The risk of developing microvascular complications is increased in people with obesity, and this is amplified in those with T2DM. The impact of metabolic surgery on microvascular complications is limited to a subgroup analysis of studies or statistical modeling to predict the glycemia-independent effect of bariatric surgery. While bariatric surgery halts the progression of retinopathy in those with minimal retinopathy, it may worsen in those with advanced retinopathy. Bariatric surgery improves proteinuria and major renal outcomes, regardless of the severity of renal impairment. Bariatric surgery in patients with obesity with or without diabetes is associated with an improvement in neuropathic symptoms and regeneration of small nerve fibers. In conclusion, bariatric surgery is associated with an improvement in microvascular complications. Further studies are needed to elucidate the underlying mechanisms for the favorable effect of bariatric surgery on microvascular outcomes.

Glomerular hyperfiltration: part 2-clinical significance in children

Glomerular hyperfiltration (GHF) is a phenomenon that can occur in various clinical conditions affecting the kidneys such as sickle cell disease, diabetes mellitus, autosomal dominant polycystic kidney disease, and solitary functioning kidney. Yet, the pathophysiological mechanisms vary from one disease to another and are not well understood. More so, it has been demonstrated that GHF may occur at the single-nephron in some clinical conditions while in others at the whole-kidney level. In this review, we explore the pathophysiological mechanisms of GHF in relation to various clinical conditions in the pediatric population. In addition, we discuss the role and mechanism of action of important factors such as gender, low birth weight, and race in the pathogenesis of GHF. Finally, in this current review, we further highlight the consequences of GHF in the progression of kidney disease.

Obesity and chronic kidney disease

The prevalence of obesity has increased dramatically during the past decades, which has been a major health problem. Since 1975, the number of people with obesity worldwide has nearly tripled. An increasing number of studies find obesity as a driver of chronic kidney disease (CKD) progression, and the mechanisms are complex and include hemodynamic changes, inflammation, oxidative stress, and activation of the renin-angiotensin-aldosterone system (RAAS). Obesity-related kidney disease is characterized by glomerulomegaly, which is often accompanied by localized and segmental glomerulosclerosis lesions. In these patients, the early symptoms are atypical, with microproteinuria being the main clinical manifestation and nephrotic syndrome being rare. Weight loss and RAAS blockers have a protective effect on obesity-related CKD, but even so, a significant proportion of patients eventually progress to end-stage renal disease despite treatment. Thus, it is critical to comprehend the mechanisms underlying obesity-related CKD to create new tactics for slowing or stopping disease progression. In this review, we summarize current knowledge on the mechanisms of obesity-related kidney disease, its pathological changes, and future perspectives on its treatment.

Youth versus adult-onset type 2 diabetic kidney disease: Insights into currently known structural differences and the potential underlying mechanisms

Type 2 diabetes (T2D) is a global health pandemic with significant humanitarian, economic, and societal implications, particularly for youth and young adults who are experiencing an exponential rise in incident disease. Youth-onset T2D has a more aggressive phenotype than adult-onset T2D, and this translates to important differences in rates of progression of diabetic kidney disease (DKD). We hypothesize that youth-onset DKD due to T2D may exhibit morphometric, metabolic, and molecular characteristics that are distinct from adult-onset T2D and develop secondary to inherent differences in renal energy expenditure and substrate metabolism, resulting in a central metabolic imbalance. Kidney structural changes that are evident at the onset of puberty also serve to exacerbate the organ’s baseline high rates of energy expenditure. Additionally, the physiologic state of insulin resistance seen during puberty increases the risk for kidney disease and is exacerbated by both concurrent diabetes and obesity. A metabolic mismatch in renal energetics may represent a novel target for pharmacologic intervention, both for prevention and treatment of DKD. Further investigation into the underlying molecular mechanisms resulting in DKD in youth-onset T2D using metabolomics and RNA sequencing of kidney tissue obtained at biopsy is necessary to expand our understanding of early DKD and potential targets for therapeutic intervention. Furthermore, large-scale clinical trials evaluating the duration of kidney protective effects of pharmacologic interventions that target a metabolic mismatch in kidney energy expenditure are needed to help mitigate the risk of DKD in youth-onset T2D.

The Diabetic Cardiorenal Nexus

The end-stage of the clinical combination of heart failure and kidney disease has become known as cardiorenal syndrome. Adverse consequences related to diabetes, hyperlipidemia, obesity, hypertension and renal impairment on cardiovascular function, morbidity and mortality are well known. Guidelines for the treatment of these risk factors have led to the improved prognosis of patients with coronary artery disease and reduced ejection fraction. Heart failure hospital admissions and readmission often occur, however, in the presence of metabolic, renal dysfunction and relatively preserved systolic function. In this domain, few advances have been described. Diabetes, kidney and cardiac dysfunction act synergistically to magnify healthcare costs. Current therapy relies on improving hemodynamic factors destructive to both the heart and kidney. We consider that additional hemodynamic solutions may be limited without the use of animal models focusing on the cardiomyocyte, nephron and extracellular matrices. We review herein potential common pathophysiologic targets for treatment to prevent and ameliorate this syndrome.

Metabolic Syndrome-Related Kidney Injury: A Review and Update

Metabolic syndrome (MetS) includes visceral obesity, hyperglycemia, dyslipidemia, and hypertension. The prevalence of MetS is 20-25%, which is an important risk factor for chronic kidney disease (CKD). MetS causes effects on renal pathophysiology, including glomerular hyperfiltration, RAAS, microalbuminuria, profibrotic factors and podocyte injury. This review compares several criteria of MetS and analyzes their differences. MetS and the pathogenesis of CKD includes insulin resistance, obesity, dyslipidemia, inflammation, oxidative stress, and endothelial dysfunction. The intervention of MetS-related renal damage is the focus of this article and includes controlling body weight, hypertension, hyperglycemia, and hyperlipidemia, requiring all components to meet the criteria. In addition, interventions such as endoplasmic reticulum stress, oxidative stress, gut microbiota, body metabolism, appetite inhibition, podocyte apoptosis, and mesenchymal stem cells are reviewed.

Diabetic kidney disease in children and adolescents: an update

Diabetic kidney disease (DKD), previously encountered predominantly in adult patients, is rapidly gaining center stage as a childhood morbidity and one that pediatric nephrologists are likely to encounter with increasing frequency. This is in large part due to the obesity epidemic and the consequent rise in type 2 diabetes in children and adolescents, as well as the more aggressive diabetes phenotype in today's youth with more rapid β-cell decline and faster development and progression of diabetes-related complications along with lower responsiveness to the treatments used in adults. DKD, an end-organ complication of diabetes, is at the very least a marker of, and more likely a predisposing factor for, the development of adverse cardiovascular outcomes and premature mortality in children with diabetes. On an optimistic note, several new therapeutic approaches are now available for the management of diabetes in adults, such as GLP1 receptor agonists, SGLT2 inhibitors, and DPP4 inhibitors, that have also been shown to have a favorable impact on cardiorenal outcomes. Also promising is the success of very low-energy diets in inducing remission of diabetes in adults. However, the addition of these pharmacological and dietary approaches to the management toolbox of diabetes and DKD in children and adolescents awaits thorough assessment of their safety and efficacy in this population. This review outlines the scope of diabetes and DKD, and new developments that may favorably impact the management of children and young adults with diabetes and DKD.

Early microvascular complications in type 1 and type 2 diabetes: recent developments and updates

The prevalence of youth-onset diabetes is progressing rapidly worldwide, and poor glycemic control, in combination with prolonged diabetes duration and comorbidities including hypertension, has led to the early development of microvascular complications including diabetic kidney disease, retinopathy, and neuropathy. Pediatric populations with type 1 (T1D) and type 2 (T2D) diabetes are classically underdiagnosed with microvascular complications, and this leads to both undertreatment and insufficient attention to the mitigation of risk factors that could help attenuate further progression of complications and decrease the likelihood for long-term morbidity and mortality. This narrative review aims to present a comprehensive summary of the epidemiology, risk factors, symptoms, screening practices, and treatment options, including future opportunities for treatment advancement, for microvascular complications in youth with T1D and T2D. We seek to uniquely focus on the inherent challenges of managing pediatric populations with diabetes and discuss the similarities and differences between microvascular complications in T1D and T2D, while presenting a strong emphasis on the importance of early identification of at-risk youth. Further investigation of possible treatment mechanisms for microvascular complications in youth with T1D and T2D through dedicated pediatric outcome trials is necessary to target the brief window where early pathological vascular changes may be significantly attenuated.

Obesity Facts and Their Influence on Renal Function Across the Life Span

Obesity is a chronic disease, with a rapidly increasing prevalence worldwide. Body mass index (BMI) provides the most useful population-level measure of overweight and obesity. For adults, overweight is defined as a BMI (Kg/m²) ≥ 25, and obesity as a BMI ≥ 30, for non-Asians and ≥ 27.5 for Asians. Abdominal obesity can be defined as a waist circumference equal to or higher than 102 cm for men and ≥88 cm for women. The definition of children and adolescents BMI changes with age and sex. Obesity may be exogenous or endogenous obesity, the latter is multifactorial and predominantly manifested during childhood. Presently, overweight and obesity are linked to more deaths worldwide than underweight. The total kidney glomerular filtration rate (GFR) is determined by the sum of nephrons and the GFR within each nephron or single nephron GFR. In clinical practice, GFR is more frequently calculated by GFR estimating equations based upon the plasma levels of creatinine, cystatin C, or both. The measured value of plasma creatinine is strongly influenced by non-GFR factors, by its tubular and gastrointestinal secretion, and by the problems associated with the lack of standardization of creatinine's laboratory assay discrediting it as an ideal GFR biomarker. Unlike creatinine, cystatin C plasma levels are mainly determined by GFR. Obesity may affect the kidney, via development of systemic arterial hypertension and/or diabetes mellitus, or directly, by ectopic accumulation of adipose tissue in the kidney. As obesity is a clinical condition associated with altered body composition, creatinine may not be the ideal biomarker for GFR measurement in obese individuals.

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

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

Obesity Related Glomerulopathy in Adolescent Women: The Effect of Body Surface Area

Background

Adolescent obesity, a risk factor for cardiorenal morbidity in adulthood, has reached epidemic proportions. Obesity-related glomerulopathy (ORG) has an early reversible stage of hyperfiltration. Age-appropriate formulae for eGFR, which are standardized to ideal body surface area (BSA) and provide assessment of kidney function in ml/min/1.73 m², may underestimate prevalence of early ORG. We investigated whether adjusting eGFR to actual BSA more readily identifies early ORG.

Methods

We studied a cohort of 22,417 young individuals, aged 12-21 years, from a New York metropolitan multi-institutional electronic health records clinical database. eGFR was calculated in two ways: BSA-standardized eGFR, and absolute eGFR. Hyperfiltration was defined above a threshold of 135 ml/min per 1.73 m² or 135 ml/min, respectively. The prevalence of hyperfiltration according to each formula was assessed in parallel to creatinine clearance.

Results

Serum creatinine values and hyperfiltration prevalence according to BSA-standardized eGFR were similar, 13%-15%, across body mass index (BMI) groups. The prevalence of hyperfiltration determined by absolute eGFR differed across BMI groups: underweight, 2%; normal weight, 6%; overweight, 17%; and obese, 31%. This trend paralleled the rise in creatinine clearance across BMI groups.

Conclusions

Absolute eGFR more readily identifies early ORG than the currently used formulae, which are adjusted to a standardized BSA and are not representative of current population BMI measures. Using absolute eGFR in clinical practice and research may improve the ability to identify, intervene, and reverse early ORG, which has great importance with increasing obesity rates.

Obesity Management and Chronic Kidney Disease

Obesity is one of the risk factors for the development and progression of chronic kidney disease (CKD). Several studies have shown the association between increased body mass index and kidney function decline. Obesity leads to CKD directly by acting as an independent risk factor and indirectly through increasing risks for diabetes, hypertension, and atherosclerosis, a group of well-established independent risk factors for CKD. Alterations in renal hemodynamics, inflammation, and in hormones and growth factors results in hyperfiltration injury and focal segmental glomerulosclerosis. In recent years, many studies have shown that the gut microbiome may play a role in the pathogenesis of obesity. Dysbiosis has been noted in obese subjects in both human and animal studies. Changes in the gut microbiome in obese patients promote weight gain by effectively extracting energy from diet, and induction of low-grade inflammation. Evidence also points to the role of inflammation within the adipose tissue in obesity as a key factor in the pathogenesis of obesity-related complications. Thus, obesity is the net result of complex interactions between behavioral, genetic, and environmental factors. In terms of management, conservative approaches are often the first option, but they often are unsuccessful in achieving and/or maintaining weight loss, particularly in severe obesity. Consequently, nonmedical management with bariatric surgery is the most effective treatment option for morbid obesity and has shown mitigation of multiple risk factors for the progression of CKD. The most frequently performed interventions are vertical sleeve gastrectomy and Roux-en-Y gastric bypass. Studies have shown that bariatric surgery is associated with beneficial effects on CKD by mitigating its risk factors by weight loss, reducing insulin resistance, hemoglobin A1c, and proteinuria, in addition to positive long-term outcomes. Because of the epidemic of obesity, the prevalence of obesity in kidney transplant recipients also is increasing. The maximal body mass index (BMI) threshold for kidney transplantation is not clear. The Organ Procurement Transplant Network/Scientific Registry of Transplant Recipients 2019 annual data report showed that the proportion of kidney transplant recipient candidates with a BMI of 30 kg/m² or greater is increasing steadily. Morbid obesity is linked to adverse graft outcomes including delayed graft function, primary nonfunction, and decreased graft survival. Obesity is also an independent risk factor for cardiovascular death in kidney transplant recipients, suggesting that these patients should not be excluded from transplantation based on their BMI because transplantation is associated with lower mortality compared with dialysis. However, many centers exclude obese patients (with different BMI cut-off values) from transplantation to avoid postoperative complications. To minimize the surgical complications of kidney transplantation in obese patients, our center has adopted the robot-assisted kidney transplantation procedure. Our data show that this approach is comparable with historical nonobese controls in the United Network for Organ Sharing database in terms of patient and graft survival. Another surgical option for this group of patients at our center is a combined robotic sleeve gastrectomy and robotic-assisted kidney transplant. In a recent study, this approach showed promising results in terms of weight loss, patient survival, and graft survival, and might become more common in the future.

The Renal Pathology of Obesity: Structure-Function Correlations

The kidney is one of the target organs that may show health disorders as a result of obesity. Obesity-related glomerulopathy (ORG) is a kidney disease category based on a biopsy diagnosis that may occur secondary to obesity. Detailed clinicopathologic observations of ORG have provided significant knowledge regarding obesity-associated renal complications. Glomerulomegaly with focal segmental glomerulosclerosis of perihilar locations is a typical renal histopathologic finding in ORG, which has long been considered to represent a state of single-nephron glomerular hyperfiltration. This hypothesis was recently confirmed in ORG patients by estimating single-nephron glomerular filtration rate using a combined image analysis and biopsy-based stereology. Overshooting in glomerulotubular and tubuloglomerular interactions may lead to glomerular hyperfiltration/hypertension, podocyte failure, tubular protein-traffic overload, and tubulointerstitial scarring, constituting a vicious cycle of a common pathway to the further loss of functioning nephrons and the progression of kidney functional impairment.

Obesity and chronic kidney disease: prevalence, mechanism, and management

The prevalence of childhood obesity is increasing worldwide at an alarming rate. While obesity is known to increase a variety of cardiovascular and metabolic diseases, it also acts as a risk factor for the development and progression of chronic kidney disease (CKD). During childhood and adolescence, severe obesity is associated with an increased prevalence and incidence of the early stages of kidney disease. Importantly, children born to obese mothers are also at increased risk of developing obesity and CKD later in life. The potential mechanisms underlying the association between obesity and CKD include hemodynamic factors, metabolic effects, and lipid nephrotoxicity. Weight reduction via increased physical activity, caloric restriction, treatment with angiotensin-converting enzyme inhibitors, and judicious bariatric surgery can be used to control obesity and obesity-related kidney disease. Preventive strategies to halt the obesity epidemic in the healthcare community are needed to reduce the widespread deleterious consequences of obesity including CKD development and progression.

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

BACKGROUND/OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

New Pandemic: Obesity and Associated Nephropathy

Incidence of obesity related renal disorders have increased 10-folds in recent years. One of the consequences of obesity is an increased glomerular filtration rate (GFR) that leads to the enlargement of the renal glomerulus, i.e., glomerulomegaly. This heightened hyper-filtration in the setting of type 2 diabetes irreparably damages the kidney and leads to progression of end stage renal disease (ESRD). The patients suffering from type 2 diabetes have progressive proteinuria, and eventually one third of them develop chronic kidney disease (CKD) and ESRD. For ameliorating the progression of CKD, inhibitors of renin angiotensin aldosterone system (RAAS) seemed to be effective, but on a short-term basis only. Long term and stable treatment strategies like weight loss via restricted or hypo-caloric diet or bariatric surgery have yielded better promising results in terms of amelioration of proteinuria and maintenance of normal GFR. Body mass index (BMI) is considered as a traditional marker for the onset of obesity, but apparently, it is not a reliable indicator, and thus there is a need for more precise evaluation of regional fat distribution and amount of muscle mass. With respect to the pathogenesis, recent investigations have suggested perturbation in fatty acid and cholesterol metabolism as the critical mediators in ectopic renal lipid accumulation associated with inflammation, increased generation of ROS, RAAS activation and consequential tubulo-interstitial injury. This review summarizes the renewed approaches for the obesity assessment and evaluation of the pathogenesis of CKD, altered renal hemodynamics and potential therapeutic targets.

The Impact of Bariatric Surgery on Renal Function: a Retrospective Analysis of Short-Term Outcomes

PURPOSE

Obesity and diabetes mellitus are now leading causes of chronic kidney disease. Our study investigated the effects of bariatric surgery on estimated glomerular filtration (eGFR) and urinary microalbumin/creatinine ratio (ACR) in morbidly obese patients.

MATERIALS AND METHODS

The clinical materials for patients who underwent bariatric surgery were retrospectively analyzed with a 6-month follow-up period between January 1, 2018, and June 1, 2020. The eGFR (ml/min) was calculated using the Cockcroft-Gault formula equation. The urinary ACR was measured during the follow-up. Body mass index (BMI, kg/m²), percent weight loss (%WL), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were recorded during the follow-up.

RESULTS

Sixty-one patients who underwent bariatric surgery-laparoscopic Roux-en-Y gastric bypass (LRYGB; n = 22) and laparoscopic sleeve gastrectomy (LSG; n = 39)-were included in this study. The eGFR of both groups decreased at the follow-up outpatient visits (p < 0.001), although eGFR did not differ between the two groups. Unexpectedly, the ACR increased in the first month after LSG (p < 0.01) but decreased with a descending trend with no significant difference (p > 0.05) throughout the remaining follow-up period. Interestingly, ACR showed a descending trend with no significant difference during the follow-up in the LRYGB group (p > 0.05). The SBP and DBP decreased after bariatric surgery, with no significant difference between the two groups (p > 0.05).

CONCLUSION

Bariatric surgery is associated with improvements in postoperative renal function 6 months following surgery. The different alterations in ACR following LSG and LRYGB procedures demonstrate the underlying mechanism.

Glomerular Diseases in Diabetic Patients: Implications for Diagnosis and Management

The prevalence of diabetes continues to rise worldwide. In addition to rising rates of diabetic kidney disease, we are also seeing a parallel rise in nondiabetic kidney disease among patients with diabetes. These nondiabetic lesions include focal segmental glomerulosclerosis, IgA nephropathy, membranous nephropathy, and other glomerular diseases. The management of diabetic kidney disease is rapidly evolving to include, beyond glycemic control and renin angiotensin inhibition, the use of sodium-glucose cotransporter 2 (SGLT2) inhibitors and mineralocorticoid receptor antagonists. These and other new treatment strategies should be applicable to managing glomerular disease in diabetic patients to reduce toxicities associated with immunosuppression and, in particular, corticosteroids. The prevalence of glomerular disease in diabetic patients is underappreciated. Diagnosis and appropriately treating these diseases remain an important avenue to modify kidney outcomes in diabetic patients.

Association of Serum Zinc Concentration with Preservation of Renal Function After Bariatric Surgery: a Retrospective Pilot Study

BACKGROUND

Although serum zinc level (Zn) is known to impact renal function in patients with diabetes, their correlation following bariatric surgery remains unknown. This study aimed at assessing the association of Zn with estimated glomerular filtration rate (eGFR) after laparoscopic sleeve gastrectomy (LSG).

METHODS

One hundred and twenty-nine patients in total (mean age, 38.1 ± 10.8; body mass index, 39.1 ± 5.1 kg/m²) with normal preoperative kidney function undergoing LSG at a single tertiary referral center were reviewed. The primary study endpoint was the relationship between Zn and post-LSG eGFR at 12-month follow-up. The secondary outcomes were the associations of percentage weight loss (%WL) with changes in Zn (△Zn) and eGFR (△eGFR).

RESULTS

The incidence of zinc deficiency was 8.5%, 8.1%, and 29.9% at baseline, post-LSG and one- and 12-month follow-up, respectively. At 12-month follow-up, Zn dropped from 104.1 ± 19.2 to 85.3 ± 38.9 μg/dL (p = 0.001), while eGFR levels decreased from 106.6 ± 10.3 to 102.1 ± 19.4 mL/min per 1.73 m² (p = 0.025). Zn correlated positively with eGFR at 6-month (r = 0.252, p = 0.037) and 12-month (r = 0.41, p = 0.001) follow-ups. Multiple linear regression analyses including baseline variables of age, sex, BMI, %WL, and diabetes identified Zn and %WL as independent predictors of eGFR at 12-month follow-up. There was no evidence of multicollinearity among these variables. Despite positive association between %WL and △eGFR (r = 0.222, p = 0.031), no correlation was noted between %WL and △Zn (r = - 0.129, p = 0.40).

CONCLUSION

The results demonstrated a positive relationship between post-LSG serum zinc levels and preservation of renal function among patients with obesity in a surgical setting. Large-scale studies are warranted to support the findings.

Bariatric Surgery Is Protective Against Renal Function Decline in Severely Obese Patients in the Long-Term

PURPOSE

This study aims to assess the long-term renal effects of bariatric surgery (BS) in severely obese patients over a follow-up period of up to 11 years.

MATERIALS AND METHODS

In a retrospective cohort study including 102 patients, patients were stratified by eGFR at baseline and divided into three groups: (1) reduced, (2) normal, and (3) increased filtration rate. Adjustments for age- and sex-related decline in eGFR were performed. We used uni- and multivariate regression analysis to identify variables that were thought to determine change in eGFR.

RESULTS

Over a median follow-up of 8.5 years (interquartile range 2.7), eGFR declined from 96.1 ± 20.7 to 84.9 ± 21.0 ml/min (p < 0.001). Among patients with (1), eGFR remained stable (69.1 ± 19.3 ml/min). Among patients with (2), eGFR declined from 99.7 ± 13.3 ml/min to 88.7 ± 19.4 ml/min (p < 0.001). Among patients with (3), eGFR decreased to normal levels (94.2 ± 17.7 ml/min, p < 0.001). Age- and sex-adjusted eGFR increased (6.4 ± 14.4 ml/min; p < 0.05) among patients with reduced filtration rate. Among patients with normal filtration rate, adjusted eGFR remained stable during follow-up (-1.3 ± 15.2 ml/min; n.s.). Among patients with increased filtration rate, adjusted eGFR decreased and remained within the normal range (-13.2 ± 12.2 ml/min; p < 0.001). Change in eGFR showed a negative correlation with eGFR at baseline (B = -0.31; p < 0.001), change in LDL-cholesterol (B = -0.09; p < 0.05), and a negative correlation with treatment requiring hypertension (B = -9.36; p = 0.001).

CONCLUSION

BS is protective against renal function decline in severely obese patients in the long term.

Influence of Weight Loss on Obesity-Associated Complications After Metabolic and Bariatric Surgery in Adolescents

OBJECTIVE

Following metabolic and bariatric surgery (MBS), most adolescents experience weight loss and improvement of many obesity-associated complications (OACs). The relationship between weight loss and remission of OACs after MBS in adolescents has not been well described.

METHODS

The Teen Longitudinal Assessment of Bariatric Surgery (Teen-LABS) is a multi-institutional prospective observational study of adolescents who underwent MBS between 2007 and 2012. Lower-weight-loss responders (LWLRs) were defined as having <20% total body weight loss (TBWL) and higher-weight-loss responders (HWLRs) were defined as having ≥20% TBWL at 5 years after MBS. The prevalence of OACs was compared at baseline and 5 years after MBS.

RESULTS

Both LWLRs (n = 114) and HWLRs (n = 78) lost significant weight within the first year following MBS; however, the TBWL at 5 years for the LWLRs was 8.6% ± 9.5% compared with 33.8% ± 9.2% for the HWLRs. Those in the HWLR group were more likely to experience durable remission of composite dyslipidemia at 5 years, whereas there were no differences between groups in remission rates of all other OACs.

CONCLUSIONS

Greater weight loss after MBS in adolescents was associated with greater remission of composite dyslipidemia; however, remission of other OACs was not dependent on major sustained weight loss.

Bariatric Surgery Improves Renal Function: a Large Inner-City Population Outcome Study

BACKGROUND

Bariatric surgery is associated with improved renal dysfunction in general population studies. The study examined the effects of bariatric surgery on renal function in a predominantly Hispanic and African American population at a community hospital in New York, USA.

METHODS

This retrospective study analyzed prospectively collected bariatric surgical data from 2247 patients (89% female) who underwent bariatric surgery at a single center. Changes in glomerular filtration rate (eGFR), urine albumin-creatinine ratio (UACR), micro- and macroalbuminuria, and hyperfiltration, which were measured preoperatively and then yearly for 3 years postoperatively, were evaluated with t tests and logistic regression analysis, after adjusting for confounding variables. The mean age of the patients at surgery was 37.1 years; the mean preoperative body mass index was 45 ± 7 kg/m².

RESULTS

The results obtained 3 years postoperatively showed the following significant improvements compared with the preoperative values: mean UACR decreased from 40.3 to 11.1 mg/g, mean eGFR improved from 79.4 to 87.3 mL/min, the prevalence of microalbuminuria decreased from 13.7 to 6.2%, the prevalence of macroalbuminuria decreased from 2.5 to 0%, and the prevalence of hyperfiltration decreased from 4.4 to 2.7% (all P < .0001). In adjusted multivariate regression analysis, these results remained significant after adjusting for age, sex, race, type of surgery, and presence of diabetes mellitus or hypertension.

CONCLUSION

In this large study at an inner-city hospital, bariatric surgery was associated with significant improvements in renal dysfunction parameters. These results could assist with informed decisions regarding indications for bariatric surgery.

Range of adiposity and cardiorenal syndrome

Obesity and obesity-related co-morbidities, diabetes mellitus, and hypertension are among the fastest-growing risk factors of heart failure and kidney disease worldwide. Obesity, which is not a unitary concept, or a static process, ranges from alterations in distribution to the amount of adiposity. Visceral adiposity, which includes intraabdominal visceral fat mass and ectopic fat deposition such as hepatic, cardiac, or renal, was robustly associated with a greater risk for cardiorenal morbidity than subcutaneous adiposity. In addition, morbid obesity has also demonstrated a negative effect on cardiac and renal functioning. The mechanisms by which adipose tissue is linked with the cardiorenal syndrome (CRS) are hemodynamic and mechanical changes, as well neurohumoral pathways such as insulin resistance, endothelial dysfunction, nitric oxide bioavailability, renin-angiotensin-aldosterone, oxidative stress, sympathetic nervous systems, natriuretic peptides, adipokines and inflammation. Adiposity and other associated co-morbidities induce adverse cardiac remodeling and interstitial fibrosis. Heart failure with preserved ejection fraction has been associated with obesity-related functional and structural abnormalities. Obesity might also impair kidney function through hyperfiltration, increased glomerular capillary wall tension, and podocyte dysfunction, which leads to tubulointerstitial fibrosis and loss of nephrons and, finally, chronic kidney disease. The development of new treatments with renal and cardiac effects in the context of type 2 diabetes, which improves mortality outcome, has highlighted the importance of CRS and its prevalence. Increased body fat triggers cellular, neuro-humoral and metabolic pathways, which create a phenotype of the CRS with specific cellular and biochemical biomarkers. Obesity has become a single cardiorenal umbrella or type of cardiorenal metabolic syndrome. This review article provides a clinical overview of the available data on the relationship between a range of adiposity and CRS, the support for obesity as a single cardiorenal umbrella, and the most relevant studies on the recent therapeutic approaches.

The Effects of Bariatric Surgery on Renal, Neurological, and Ophthalmic Complications in Patients with Type 2 Diabetes: the Taiwan Diabesity Study

Background

Bariatric surgery has been shown to improve glycemic control in patients with type 2 diabetes. However, less is known whether it can also reduce diabetic renal, neurological, and ophthalmic complications.

Methods

This prospective multicenter cohort study compared renal, ophthalmic, and neurological complications between 49 patients with obesity/overweight receiving bariatric surgery and 338 patients receiving standard medical treatment after follow-up for 2 years. Patients received neurological examinations including toe tuning fork vibration test, ankle tendon reflex test, 10-g monofilament test, and ophthalmic examinations including visual acuity measurement and fundus examinations. Multiple regressions, propensity score weighting, and matching were employed to adjust for baseline differences.

Results

After 2 years of follow-up, patients with type 2 diabetes receiving bariatric surgery had greater reduction in BMI, HbA1c, and urine albumin–creatinine ratio, greater improvement in estimated glomerular filtration rate, and greater increase in tuning fork test score of right and left toes compared with the medical group. However, there is no improvement in 10 g-monofilament test, visual acuity, diabetic non-proliferative retinopathy, and proliferative retinopathy. Similar results were obtained using multiple regression adjustment, propensity-score weighting, or comparing age-, sex-, and BMI-matched subjects.

Conclusions

After 2-year follow-up, patients with obesity/overweight and type 2 diabetes receiving bariatric surgery have increased glomerular filtration rate, reduced albuminuria, and improved tuning folk vibration sensation.

Electronic supplementary material

The online version of this article (10.1007/s11695-020-04859-9) contains supplementary material, which is available to authorized users.

Are My Pediatric Patients at Increased Risk of Developing Chronic Kidney Disease?

Chronic kidney disease (CKD) is an underrecognized and often undiagnosed cause of morbidity and mortality. Many children and adolescents are at increased risk of developing CKD as they mature and age, secondary to conditions commonly cared for by pediatric health professionals. Prematurity, diabetes mellitus, hypertension, congenital heart disease, sickle cell disease and trait, severe obesity, cancer chemotherapy, other drug toxicities, and systemic situations that may cause acute kidney injury such as sepsis or extracorporeal membrane oxygenation therapy predispose to potential CKD. Clinicians should be aware of these conditions in order to screen for CKD, choose non-nephrotoxic treatments for these children whenever possible, and treat or refer those who have early signs of CKD.

Five-year kidney outcomes of bariatric surgery differ in severely obese adolescents and adults with and without type 2 diabetes

Bariatric surgery improves markers of kidney health in severe obesity, yet it is unclear if kidney disease outcomes differ according to age at surgery. Therefore, we examined health effects of Roux-en-Y gastric bypass between 161 adolescents and 396 adults participating in two related but distinct studies. Primary outcomes were elevated urine albumin-to-creatinine ratio (UACR) of 30 mg/g or more and hyperfiltration (an estimated glomerular filtration rate of 135 ml/min/1.73m² or more). Analyses were stratified by the presence of pre-operative type 2 diabetes. Adolescents with pre-operative type 2 diabetes had a significantly increased prevalence of elevated UACR prior to surgery compared to adults (22.5 vs. 9.0%). Resolution of elevated UACR following surgery differed between adolescents and adults with type 2 diabetes, with adolescents experiencing a significantly earlier improvement following surgery. Adolescents without pre-operative type 2 diabetes demonstrated a significantly increased prevalence of UACR prior to surgery compared to adults (9.4 vs. 4.5%), with no improvement occurring in either group post-operatively. Adolescents with pre-operative type 2 diabetes had a significantly increased prevalence of hyperfiltration that remained throughout the study period, whereas hyperfiltration prevalence was similar among those without type 2 diabetes. Thus, adolescents with pre-operative type 2 diabetes experienced earlier attenuation of elevated UACR compared to adults with pre-operative type 2 diabetes in response to gastric bypass.

Bariatric surgery and kidney disease outcomes in severely obese youth

Bariatric surgery, an emerging treatment for severely obese youth with and without T2D, provides marked improvement in insulin resistance, beta-cell function, and central adiposity. Further, preliminary data suggest that bariatric surgery also results in significant improvement in markers of obesity-related nephropathy and DKD, beyond that which can be achieved with current medical interventions. Yet, the mechanisms whereby bariatric surgery attenuates kidney disease remain unclear. This review summarizes the data on the effects of bariatric surgery on obesity-related nephropathy and DKD in youth with and without T2D, in addition to potential mechanisms underlying the nephroprotective effects of weight loss surgery and how these may differ in Roux-en-Y gastric bypass vs. vertical sleeve gastrectomy. Finally, we discuss potential future non-surgical therapies to mitigate kidney disease.

Effect of Surgical Versus Medical Therapy on Diabetic Kidney Disease Over 5 Years in Severely Obese Adolescents With Type 2 Diabetes

OBJECTIVE

To compare diabetic kidney disease (DKD) rates over 5 years of follow-up in two cohorts of severely obese adolescents with type 2 diabetes (T2D) undergoing medical or surgical treatment for T2D.

RESEARCH DESIGN AND METHODS

A secondary analysis was performed of data collected from obese participants of similar age and racial distribution enrolled in the Teen-Longitudinal Assessment of Bariatric Surgery (Teen-LABS) and the Treatment Options of Type 2 Diabetes in Adolescents and Youth (TODAY) studies. Teen-LABS participants underwent metabolic bariatric surgery (MBS). TODAY participants were randomized to metformin alone or in combination with rosiglitazone or intensive lifestyle intervention, with insulin therapy given for glycemic progression. Glycemic control, BMI, estimated glomerular filtration rate (eGFR), urinary albumin excretion (UAE), and prevalence of hyperfiltration (eGFR ≥135 mL/min/1.73 m²) and elevated UAE (≥30 mg/g) were assessed annually.

RESULTS

Participants with T2D from Teen-LABS (n = 30, mean ± SD age, 16.9 ± 1.3 years; 70% female; 60% white; BMI 54.4 ± 9.5 kg/m²) and TODAY (n = 63, age 15.3 ± 1.3 years; 56% female; 71% white; BMI 40.5 ± 4.9 kg/m²) were compared. During 5 years of follow-up, hyperfiltration decreased from 21% to 18% in Teen-LABS and increased from 7% to 48% in TODAY. Elevated UAE decreased from 27% to 5% in Teen-LABS and increased from 21% to 43% in TODAY. Adjusting for baseline age, sex, BMI, and HbA_1c, TODAY participants had a greater odds of hyperfiltration (odds ratio 15.7 [95% CI 2.6, 94.3]) and elevated UAE (27.3 [4.9, 149.9]) at 5 years of follow-up.

CONCLUSIONS

Compared with MBS, medical treatment of obese youth with T2D was associated with a higher odds of DKD over 5 years.

Central blood pressure in morbid obesity and after bariatric surgery

Various mechanisms are related to arterial hypertension in obesity. Central blood pressure (BP) seems to correlate more than peripheral BP with future cardiovascular risk. Bariatric surgery is an effective method to reduce BP along with weight loss in patients with morbid obesity. The study of the relationship between weight modification after bariatric surgery and ambulatory BP measurement, not only peripheral BP, but also central BP, could provide information regarding the mechanisms of organic damage associated with elevated BP in obesity. In this review we analyze the available evidence regarding the association between central BP with obesity and its modifications after bariatric surgery.

Can childhood obesity influence later chronic kidney disease?

Childhood overweight and obesity affects more and more children. Whilst associations of childhood overweight with later outcomes such as hypertension, diabetes and cardiovascular disease have been well documented, less is known about the association of childhood overweight and obesity with kidney disease. We review the existing evidence for the association of childhood obesity with markers of childhood and adult kidney disease. Whilst there is some evidence for an association, studies have not been able to distinguish between childhood being a sensitive time to develop later kidney problems, or whether observed associations of childhood obesity with poor outcomes are driven by greater lifelong exposure to obesity.

Impact of serum uric acid on renal function after bariatric surgery: a retrospective study

BACKGROUND

Despite a known negative association between serum uric acid level (SUA) and renal function, this correlation in patients after bariatric surgery remains unknown.

OBJECTIVE

To assess correlation between postoperative SUA and estimated glomerular filtration rate (eGFR) at 12 months after bariatric surgery.

SETTING

A single tertiary referral center.

METHODS

A total of 252 patients (age = 40.5 ± 11.2; body mass index = 39.0 ± 5.5 kg/m²) undergoing bariatric surgery divided into 2 groups (i.e., normal renal function [90 ≤ eGFR < 125 mL/min/1.73 m², n = 176] versus renal function impairment [eGFR < 90 mL/min/1.73 m², n = 76]) were assessed for relationships between SUA and eGFR in both groups (primary endpoint) and associations of percentage weight loss with changes in SUA (△SUA) and eGFR (△eGFR) for all patients (secondary endpoint) at 12 months.

RESULTS

Overall, prevalence of hyperuricemia was 40.4% and 22.2% (baseline and postoperative 12 mo, respectively). Reverse relationship was observed between SUA and eGFR (r = -.152, P = .007) for all patients with no association noted between baseline SUA and eGFR in each group as well as between SUA and eGFR at 12 months in the normal group (r = -.076, P = .437). The reverse relationship was found (r = -.417, P = .005) in renal function impairment group for whom SUA was identified as a predictor of eGFR at 12 months. There was no association of percentage weight loss with △SUA (r = .089, P = .601) and △eGFR (r = -.046, P = .785).

CONCLUSION

The results demonstrated a negative relationship between postoperative SUA and renal function in patients with preexisting renal dysfunction undergoing bariatric surgery. Clinical significance of our findings warrants further investigation.

Severe Obesity in the Pediatric Population: Current Concepts in Clinical Care

PURPOSE OF REVIEW

This review describes (1) the clinical assessment of pediatric patients with severe obesity, including a summary of salient biological, psychological, and social factors that may be contributing to the patient's obesity and (2) the current state of treatment strategies for pediatric severe obesity, including lifestyle modification therapy, pharmacotherapy, and metabolic and bariatric surgery.

RECENT FINDINGS

Lifestyle modification therapy alone is insufficient for achieving clinically significant BMI reduction for most youth with severe obesity and metabolic and bariatric surgery, though effective and durable, is not a scalable treatment strategy. Pharmacological agents in the pipeline may 1 day fill this gap in treatment. Treatment of severe pediatric obesity requires a chronic care management approach utilizing multidisciplinary teams of health care providers and multi-pronged therapies.

Cardiometabolic risk in obese children

Obesity in childhood remains a significant and prevalent public health concern. Excess adiposity in youth is a marker of increased cardiometabolic risk (CMR) in adolescents and adults. Several longitudinal studies confirm the strong association of pediatric obesity with the persistence of adult obesity and the future development of cardiovascular disease, diabetes, and increased risk of death. The economic and social impact of childhood obesity is further exacerbated by the early onset of the chronic disease burden in young adults during their peak productivity years. Furthermore, rising prevalence rates of severe obesity in youth from disadvantaged and/or minority backgrounds have prompted the creation of additional classification schemes for severe obesity to improve CMR stratification. Current guidelines focus on primary obesity prevention efforts, as well as screening for clustering of multiple CMR factors to target interventions. This review summarizes the scope of the pediatric obesity epidemic, the new severe obesity classification scheme, and examines the association of excess adiposity with cardiovascular and metabolic risk. We will also discuss potential questions for future investigation.

Childhood Obesity and the Metabolic Syndrome

Obesity is a leading cause of chronic kidney disease. Children with severe obesity have an increased prevalence of early kidney abnormalities and are at high risk to develop kidney failure in adulthood. The pathophysiology of obesity-related kidney disease is incompletely understood, although the postulated mechanisms of kidney injury include hyperfiltration, adipokine dysregulation, and lipotoxic injury. An improved understanding of the long-term effects of obesity on kidney health is essential treat the growing epidemic of obesity-related kidney disease. The purpose of this article is to review the epidemiology, pathophysiology, clinical features, and management of obesity-related kidney disease in children and adolescents.

Composite Health Outcomes in Pediatric and Young Adult Kidney Transplant Recipients

OBJECTIVE

To assess composite health outcomes in pediatric and young adult kidney transplant recipients following kidney transplantation.

STUDY DESIGN

We conducted a cross-sectional study of all recipients at our center who had a 1-, 3-, 5-, and/or 10-year transplant anniversary visit between October 2008 and February 2015. The kidney transplant recipients were assessed at each time point according to an outcome measure consisting of 15 pass/fail criteria in 5 domains: allograft health, rejection and immunology, infection, cardiovascular health, and growth.

RESULTS

We analyzed 148 patients at 231 transplantation anniversary visit time points; 52 of 82 (63%) patients assessed at 1 year had an ideal outcome, meeting at least 13 of the 15 criteria. This decreased to 37% at year 3, 40% at year 5, and 26% at year 10 (P < .01). The most common failures across all time points occurred in the domains of growth (43%-52% passing) and cardiovascular health (33%-51% passing). Allograft health declined significantly, decreasing from 74% at year 1 to 33% at year 10 (P < .01). The percentage of patients with graft failure increased from 2.4% at 1 year to 39.5% at 10 years (P < .01), and patient deaths increased from 0 to 11% (P < .01) in the same time frame.

CONCLUSIONS

Ideal outcomes for pediatric kidney transplant recipients decrease over time with growth, cardiovascular health, and allograft health as the primary failure modes. Understanding the composite health of young recipients will allow primary care providers and nephrologists alike to evaluate the overall health of kidney transplant recipients and focus clinical care on the most common sequelae.

Prevalence of Chronic Kidney Disease in Morbidly Obese Japanese and the Impact of Bariatric Surgery on Disease Progression

BACKGROUND

The prevalence of chronic kidney disease (CKD) among Japanese morbidly obese patients undergoing bariatric surgery and the impact of bariatric surgery on their renal function has not previously been investigated.

OBJECTIVES

The aims were to assess the prevalence of CKD patients who underwent bariatric surgery in our institution and to elucidate the impact of bariatric surgery on their kidney function as measured by the estimated glomerular filtration rate by Cystatin-C (eGFRcys).

SETTING

The setting of the study was in a single private hospital.

METHODS

Two hundred fifty-four consecutive Japanese patients who underwent bariatric surgery were retrospectively analyzed to elucidate the prevalence of CKD. The eGFRcys was calculated to assess the change in the kidney function for 1 year after surgery.

RESULTS

The preoperative prevalence of CKD was as follows: G1, 45.3%; G2, 47.2%; G3, 6.5%; and G4, 0.9%. The eGFRcys values before and after surgery were compared; the G1 and G2 patients showed significantly improved eGFRcys values after surgery (G1 101 [94-108] vs 114 [103-127]; G2 79 [74-84] vs 97 [87-104] ml/min/1.73 m²; p < 0.01) with significant weight loss (G1 38.1 ± 6.2 vs 26.5 ± 3.4; G2 38.5 ± 6.9 vs 26.7 ± 3.6 kg/m²; p < 0.01). Although the renal function of G3 patients was not improved after surgery (44 [42-47] vs 45 [43-63] ml/min/1.73 m²; p = 0.08), successful weight loss was achieved (36.1 ± 6.3 vs 26.6 ± 3.6 kg/m²; p < 0.01). In multivariate analysis, postoperative eGFRcys correlated negatively with proteinuria (p < 0.01), age (p < 0.01), and body mass index (p < 0.01) and positively with persistence of antihypertensive drugs.

CONCLUSION

Bariatric surgery resulted in the significant improvement in the eGFRcys values of Japanese patients with morbid obesity, particularly those with pre-CKD (eGFRcys ≥ 60 ml/min/1.73 m²), while the eGFRcys values of CKD patients (< 60 ml/min/1.73 m²) were not ameliorated by surgery.

Preventive Nephrology: The Role of Obesity in Different Stages of Chronic Kidney Disease

BACKGROUND

Obesity is increasing worldwide and has become a nontraditional risk factor in chronic kidney disease (CKD).

SUMMARY

Obesity-related nephropathy may aggravate renal complications of the metabolic syndrome and progress to advanced CKD stages, while obesity in early stages of CKD is clearly related to the development of kidney disease. A high body mass index (BMI) in advanced CKD stages and dialysis is an advantage for survival (so called "obesity paradox"). A high lean body to fat mass index indicates a beneficial state of body composition. In contrast, loss of muscle mass with increasing fat mass causes "sarcopenia obesity," which is related to unfavorable outcomes in renal replacement therapy. Obesity (BMI > 30-35) in renal transplant recipients is associated with a higher risk of complications such as delayed graft function, increased rates of rejection, and graft loss. While conservative management of morbid obesity is failing in most cases, bariatric surgery seems to be an option in some cases to improve renal complications in the early stage of CKD or in transplant candidates.

KEY MESSAGE

In conclusion, obesity is increasingly prevalent among CKD patients. Adequate management with respect to the specific role of obesity in different stages of CKD should be integrated in routine renal care.

Treatment Options for Severe Obesity in the Pediatric Population: Current Limitations and Future Opportunities

OBJECTIVE

Severe obesity is the only obesity classification increasing in prevalence among children and adolescents. Treatment options that produce meaningful and sustained weight loss and comorbidity resolution are urgently needed.

METHODS

The purpose of this review is to provide a brief overview of the current treatment options for pediatric severe obesity and offer suggestions regarding future opportunities for accelerating the development and evaluation of innovative treatment strategies.

RESULTS

At present, there are three treatment options for youth with severe obesity: lifestyle modification therapy, pharmacotherapy, and bariatric surgery. Lifestyle modification therapy can be useful for improving many chronic disease risk factors and comorbid conditions but often fails to achieve clinically meaningful and sustainable weight loss. Pharmacotherapy holds promise as an effective adjunctive treatment but remains in the primordial stages of development in the pediatric population. Bariatric surgery provides robust weight loss and risk factor/comorbidity improvements but is accompanied by higher risks and lower uptake compared to lifestyle modification therapy and pharmacotherapy. New areas worth pursuing include combination pharmacotherapy, device therapy, identification of predictors of response aimed at precision treatment, and interventions in the postbariatric surgical setting to improve long-term outcomes.

CONCLUSIONS

Treating pediatric severe obesity effectively and safely is extremely challenging. Some progress has been made, but substantially more effort and innovation are needed in the future to combat this serious and ongoing medical and public health issue.

Longitudinal assessment of renal function in native kidney after bariatric surgery

The epidemic of obesity parallels that of chronic kidney disease (CKD). Obesity worsens the course of CKD, mainly defined by an abnormal glomerular filtration rate (GFR). Patients with severe obesity stages (II and III with body mass index >35 kg/m²) are eligible for bariatric surgery (BS), which is the most efficient method of achieving durable weight loss. BS may reverse glomerular hyperfiltration and albuminuria, improve adipocytokine profile, and relieve diabetes and hypertension. Obesity remission after BS might prevent the progression of renal failure in populations with morbid obesity. However, evidence for the beneficial effect of BS on renal function is scant. This lack of knowledge is mainly due to methodologic reasons, which are addressed in this review. The reversibility of hyperfiltration due to the presence of functional renal reserve hampers the interpretation of changes in true GFR after BS. This true GFR is only obtained with the renal clearance of an exogenous filtration marker. Estimation of GFR is generally provided by prediction equations, namely by modification of diet in renal diseases or by chronic kidney disease-epidemiology collaborative group. These equations are not accurate because the serum levels of both creatinine and cystatin C depend on extrarenal factors, which are modified by BS. Comparing the slopes of measured GFR according to various durations of exposure with morbid obesity would be critical in providing reliable data. Herein, we review the current knowledge on the effects of BS on kidney function; we specify the methodologic issues and particularities of the dietary management of CKD patients to propose reliable directions for future clinical research.