Nitric oxide as treatment for an emerging epidemic of obesity-related glomerulopathy

Parental obesity predisposes offspring to kidney dysfunction and increased susceptibility to ischemia-reperfusion injury in a sex-dependent manner

Although obesity is recognized as a risk factor for cardiorenal and metabolic diseases, the impact of parental obesity on the susceptibility of their offspring to renal injury at adulthood is unknown. We examined the impact of parental obesity on offspring kidney function, morphology, and markers of kidney damage after acute kidney injury (AKI). Offspring from normal (N) diet-fed C57BL/6J parents were fed either N (NN) or a high-fat (H) diet (NH) from weaning until adulthood. Offspring from obese H diet-fed parents were fed N (HN) or H diet (HH) after weaning. All offspring groups were submitted to bilateral AKI by clamping the left and right renal pedicles for 30 min. Compared with male NH and NN offspring from lean parents, male HH and HN offspring from obese parents exhibited higher kidney injury markers such as urinary, renal osteopontin, plasma creatinine, urinary albumin excretion, and neutrophil gelatinase-associated lipocalin (NGAL) levels, and worse histological injury score at 22 wk of age. Only albumin excretion and NGAL were elevated in female HH offspring from obese parents compared with lean and obese offspring from lean parents. We also found an increased mortality rate and worse kidney injury scores after AKI in male offspring from obese parents, regardless of the diet consumed after weaning. Female offspring were protected from major kidney injury after AKI. These results indicate that parental obesity leads to increased kidney injury in their offspring after ischemia-reperfusion in a sex-dependent manner, even when their offspring remain lean.NEW & NOTEWORTHY Offspring from obese parents are more susceptible to kidney injury and worse outcomes following an acute ischemia-reperfusion insult. Male, but not female, offspring from obese parents exhibit increased blood pressure early in life. Female offspring are partially protected against major kidney injury induced by ischemia-reperfusion.

Renal stone disease and obesity: what is important for urologists and nephrologists?

Currently, obesity has reached an epidemic stage and represents a challenge for health authorities across the globe. Certainly, with emergence of obesity epidemic, we started to see an increase in the prevalence of chronic kidney disease (CKD) and nephrolithiasis. Interestingly, epidemiologic studies have shown that the incident stone risk increases with body mass index (BMI), and no further increase in risk is noticed when the BMI > 30 kg/m(2). Furthermore, metabolic syndrome and diabetes are also associated with an increase in the incidence of renal stones disease. The shared links between these metabolic disorders are insulin resistance. Furthermore, insulin resistance is thought to alter renal acid-base metabolism, resulting in a lower urine pH and increased risk of uric acid stone disease. Obesity is also associated with excess nutritional intake of lithogenic substances such as refined sugars, low fluid intake, calcium, oxalate, and purine-rich foods. Obesity is also associated with an increase in incidence of urinary tract infection. Recent reports suggested that renal stone disease carries risk of myocardial infarction, progression of CKD, and diabetes. Alarmingly, orlistat (obesity medication) and bariatric surgery are associated with hyperoxaluria and associated stone formation and even oxalate nephropathy. Certainly, the many health risks of obesity, including nephrolithiasis, will add more burden on urologists and nephrologists. Shockwave lithotripsy, percutaneous nephrolithotomy, and ureteroscopy are all safe procedures in obese individuals. Further research is urgently needed to address the pathophysiology and management of obesity-induced renal stones disease.

The impact of renal function on outcomes of bariatric surgery

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

Orlistat and calcium oxalate crystalluria: an association that needs consideration

Obesity is currently an epidemic across the globe. Obese patients unable to achieve significant weight loss with lifestyle changes alone may require drug therapy. Clinical trials have shown that orlistat administration may not only lead to weight loss but also protect against type 2 diabetes in around 37% of cases. Orlistat can induce and maintain weight loss, even in patients with comorbid conditions such as hypertension or type 2 diabetes. Recently, orlistat can induce marked weight loss in individuals with chronic kidney disease (CKD). In small numbers of individuals especially those with CKD, orlistat administration may precipitate oxalate nephropathy and renal stone disease. The focus of this article is to review current studies showing impact of orlistat on renal function and outcomes.

Bariatric surgery and renal function: a precarious balance between benefit and harm

Medical treatment of obesity and lifestyle modification have limited effectiveness in treating it in morbidly obese individuals. Importantly, bariatric surgery is regarded as the only therapy that is effective in maintaining significant weight loss in morbidly obese individuals. Despite the fact that bariatric surgery-induced weight loss is associated with a significant decrease in morbidity and mortality and improvement in renal function, bariatric surgery has recently been shown to be associated with a significant risk of nephrolithiasis. The main risk factor for nephrolithiasis is increased excretion of urinary oxalate. In this review, we discuss the association between bariatric surgery, an increased risk of renal stone formation and oxalate nephropathy.