Gastric bypass and resolution of proteinuria in an obese diabetic patient

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.

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.

Bariatric surgery and the kidney-much benefit, but also potential harm

Bariatric surgery is increasingly performed on overweight individuals. A significant benefit with respect to cardiovascular (CV) events and survival has been documented. After weight loss, reduction of albuminuria/proteinuria is almost consistently seen; small studies documented retardation of the glomerular filtration rate (GFR) loss after bariatric surgery; reduction of blood pressure (BP) is less consistent. It has been known for a long time that the frequency of oxalate stones is increased after bariatric surgery. The main renal threat of hyperoxaluria is renal oxalosis, often irreversible, causing persisting renal failure. The causes are reduced oxalate binding by calcium due to saponification of calcium causing fat malabsorption, increased permeability for oxalate because of increased permeability of colon mucosa triggered by increased bile salts and reduced colonization of the colon by oxalobacter formigenes. These mechanisms are susceptible to treatment.

The effect of weight loss in obesity and chronic kidney disease

Several epidemiologic investigations have confirmed that obesity is a significant risk factor for the appearance of proteinuria and end-stage kidney disease in a normal population. Weight loss induced by low-calorie diets, physical exercise, or bariatric surgery is accompanied by an important antiproteinuric effect. Reduction in proteinuria is already observed after a few weeks from the onset of weight loss and it is evident even in patients with modest weight losses. Reduction in proteinuria by weight loss has been described in chronic proteinuric nephropathies of different etiologies. The mechanisms through which weight loss may reverse proteinuria are likely to be plural: better control of blood pressure, improvement of serum lipid profile, improvement of insulin sensitivity, better glycemic control in diabetes patients, decrease of circulating leptin levels, reversal of glomerular hyperfiltration, and decreased activation of the renin-angiotensin-aldosterone system.

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.

Effect of bariatric surgery on normal and abnormal renal function

BACKGROUND

Obesity has been associated with hypertension, diabetes mellitus, and metabolic syndrome, risk factors for chronic kidney disease. In addition, obesity has been found to have an independent, negative effect on renal function and the progression of renal insufficiency.

METHODS

The serum creatinine (CR) in 813 patients who had undergone obesity surgery from 2003 to 2009 at a large academic medical center and had been followed up for ≥24 months was retrospectively monitored. Renal function, as measured by the CR level, was assessed at baseline and at 6, 12, and ≥24 months of follow-up. The groups were stratified by the baseline CR as follows: normal (CR <1.3 mg/dL), mild impairment (CR 1.3-1.6 mg/dL), and moderate impairment (CR >1.6 mg/dL).

RESULTS

Of the 813 patients, 757 had a CR <1.3 mg/dL at baseline. Of those 757 patients, 97.6% had maintained a CR of <1.3 mg/dL, 1.3% had a CR of 1.3-1.6 mg/dL, 1.1% had a CR of >1.6 mg/dL (n = 757) at 6 months of follow-up. At 1 year of follow-up, 99% had maintained a CR of <1.3 mg/dL and 1% had a CR of >1.3% (n = 509). At 2 years of follow-up, 100% had a CR value of <1.3 mg/dL (n = 388). Of the remaining 56 patients, 71.4% had been classified as having mild impairment (CR 1.3-1.6 mg/dL) and 28.5% as having moderate impairment (CR >1.6 mg/dL) before weight loss surgery. Examination of the CR values at ≥2 years after weight loss surgery demonstrated that 76.7% had a normal CR level, 12.5% had mild impairment, and 10.7% had moderate impairment.

CONCLUSION

Bariatric surgery does not have a negative effect on renal function as measured by the CR, whether CR at baseline is <1.3 or ≥1.3 mg/dL when monitored for ≥24 months. For those with impaired renal function and a CR ≥1.3 mg/dL, improvement in CR was seen in 76.7% at ≥2 years postoperatively, at a point at which the weight loss velocity, hydration, and nutritional status have stabilized. The weight loss associated with bariatric surgery could potentially have a positive effect on renal function at ≥24 months, such as was found in the present study by a stable or reduced CR level. The etiology for this might be a direct effect of weight loss on impaired renal function or an indirect effect by reducing the rates of co-morbidities, such as diabetes mellitus and hypertension, both risk factors for renal disease. Additional prospective studies, including weight-matched controls, are needed.

Body weight control by a high-carbohydrate/low-fat diet slows the progression of diabetic kidney damage in an obese, hypertensive, type 2 diabetic rat model

Obesity is one of several factors implicated in the genesis of diabetic nephropathy (DN). Obese, hypertensive, type 2 diabetic rats SHR/NDmcr-cp were given, for 12 weeks, either a normal, middle-carbohydrate/middle-fat diet (MC/MF group) or a high-carbohydrate/low-fat diet (HC/LF group). Daily caloric intake was the same in both groups. Nevertheless, the HC/LF group gained less weight. Despite equivalent degrees of hypertension, hyperglycemia, hyperlipidemia, hyperinsulinemia, and even a poorer glycemic control, the HC/LF group had less severe renal histological abnormalities and a reduced intrarenal advanced glycation and oxidative stress. Mediators of the renoprotection, specifically linked to obesity and body weight control, include a reduced renal inflammation and TGF-beta expression, together with an enhanced level of adiponectin. Altogether, these data identify a specific role of body weight control by a high-carbohydrate/low-fat diet in the progression of DN. Body weight control thus impacts on local intrarenal advanced glycation and oxidative stress through inflammation and adiponectin levels.

Obesity, diabetes, and chronic kidney disease

Similar to diabetes, obesity is associated with the early onset of glomerulomegaly, hemodynamic changes of a hyperfiltering kidney, and increased albuminuria, which are potentially reversible with weight loss. However, the pathologic lesions of focal segmental glomerulosclerosis in experimental models of sustained obesity, and in obese humans presenting with massive proteinuria, are different from those of classic diabetic nephropathy. In addition, several observational, cross-sectional, and longitudinal studies document obesity as an independent risk factor for the onset, aggravated course, and poor outcomes of chronic kidney disease, even after adjustment for confounding comorbidities, including diabetes and hypertension, the two major causes of chronic kidney disease.

Obesity, proteinuria and progression of renal failure

PURPOSE OF REVIEW

Recent studies have reported an alarming increase in the incidence of obesity-related glomerulopathy, in a context of a worldwide spread of obesity.

RECENT FINDINGS

Several epidemiological investigations have confirmed that obesity is a significant risk factor for the appearance of proteinuria and end-stage renal disease in a normal population. Obesity-induced hemodynamic changes and glomerular deposition of lipids (partly mediated by sterol regulatory element-binding proteins) play an important role in the pathogenesis of obesity-related renal disease. In addition, the renin-angiotensin-aldosterone system is markedly activated in obesity, adipocytes being an important source of these hormones. Weight loss induces a marked reduction in all renin-angiotensin-aldosterone system components. Patients with reduced renal mass of any origin appeared to be particularly susceptible to the detrimental influence of obesity: body mass index was the most important risk factor for the development of proteinuria and renal insufficiency in patients with unilateral renal agenesis, unilateral nephrectomy and remnant kidneys. Weight loss induces a very important reduction in proteinuria in chronic proteinuric nephropathies of different etiologies.

SUMMARY

Prevention and treatment of obesity should be a first-line objective in the therapeutic approach of patients with diabetic and nondiabetic chronic renal diseases.

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.