Renal Stone Disease and Obesity: What is Important for Urologists and Nephrologists?

Abstract

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 acidbase 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.

Urological Procedures in Urolithiasis and Their Association with Chronic Kidney Disease

“…[1][2][3]7 There was no statistically significant difference among them except obesity.Obesity has reached an epidemic stage, and an increase in the incidence of CKD and nephrolithiasis has been demonstrated in obese patients. 1,20 It is associated with higher incidence of urinary tract infections, excessive intake of lithogenic substances (purine-rich, calcium, and oxalate), and low fluid intake. Orlistat and bariatric surgeries are associated with hyperoxaluria with increased risk for subsequent stone formation and oxalate nephropathy.…”

Shock Wave Lithotripsy Does Not Impair Renal Function in a Swine Model of Metabolic Syndrome

“…4,6,10,11,18 The modality of stone removal could also add to this risk if it results in deterioration in renal function due to loss of renal parenchyma.…”

“…4 Indeed, as the number of components of MetS increases the association with CKD is strenthened. 5 Obesity and MetS are also known to increase the risk of urolithiasis [6][7][8][9] -an independent risk factor for CKD. 10,11 Therefore, MetS patients who form kidney stones have contributing risk factors for CKD.…”

Bariatric Surgery and Urinary Stone Disease

“…Morbid obez hastalarda diyet değişiklikleri, farmakolojik tedavi ve yaşam tarzı modifikasyonları gibi konservatif yöntemler nadiren anlamlı ve kalıcı kilo kaybına neden olurlar [12]. Bu nedenle, etkili kilo kaybı, obezite ile ilişkili hastalıklarda düzelme ve uzun dönem mortalitede azalma sağlayan obezite cerrahisinin kullanımı giderek yaygınlaşmaktadır [13,14]. Bununla birlikte, obezite gibi, obezite cerrahisi de üriner sistem taş hastalığı için bir risk faktörü gibi görünmektedir [14].…”

“…Bu nedenle, etkili kilo kaybı, obezite ile ilişkili hastalıklarda düzelme ve uzun dönem mortalitede azalma sağlayan obezite cerrahisinin kullanımı giderek yaygınlaşmaktadır [13,14]. Bununla birlikte, obezite gibi, obezite cerrahisi de üriner sistem taş hastalığı için bir risk faktörü gibi görünmektedir [14]. Bu derlemede modern obezite cerrahisi yöntemleri ile üriner sistem taş hastalığı arasındaki ilişki ve obezite cerrahisi sonrası taş oluşumu gözlenen hastaların değerlendirme süreci tartı-şılmıştır.…”