Ahmed MH et al, 2012: Renal stone disease and obesity: what is important for urologists and nephrologists?
Ahmed MH, Ahmed HT, Khalil AA.
Department of Medicine, Wexham Park Hospital, Slough, Berkshire, UK
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/m2. 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.
Ren Fail. 2012;34(10):1348-54. doi: 10.3109/0886022X.2012.723777. Epub 2012 Sep 26.
PMID: 23013150 [PubMed - in process]
This review article is of interest inasmuch as it outlines the relationship between obesity and renal stone disease. The obesity induced stone disease is a growing global problem that needs recognition by urologists as well as nephrologists. The association of obesity and the metabolic syndrome leads to several abnormalities in urine composition with increased risk of calcium oxalate as well as uric acid stone formation. (The prevalence of uric acid stones that the authors give for the Mediterranean and Middle Eastern countries is, however, higher than I have seen before.) Attention has to be paid to these problems because recurrence prevention will become necessary in patients both with and without residual fragments/stones after various stone removing procedures. Otherwise we will probably get a dramatically increased cost for active stone removal. The article is worthwhile to consider for all urologists dealing with stone forming patients.