Association of body mass index and urine pH in patients with urolithiasis

Abstract

Increase in body size increases the risk of renal stone formation. The mechanism explaining this relationship remains unclear. Urine pH is one of the important factors for urinary stone formation. The purpose of this study was to determine whether there is an association between urine pH and body mass index (BMI) in patients with urolithiasis. Medical charts review that included 342 urinary stone formers (248 men and 94 women). Data obtained included patient sex, age, BMI, urine pH at diagnosis, and stone composition. The patients were classified as normal weight (18.5 <or= BMI < 24), overweight (24 <or= BMI < 27), or obese (BMI >or= 27). The mean urine pH of the normal body weight, overweight, and obese groups was 6.25, 6.14, and 6.00, respectively (P < 0.05). Urine pH is inversely related to BMI among patients with urolithiasis. Among patients with urolithiasis, higher BMI will have lower urine pH. This may explain why obesity is associated with an increased risk of nephrolithiasis. Weight loss should be explored as a potential treatment to prevent kidney stone formation. The prevention of urinary stone disease gives clinicians an additional reason to encourage weight reduction through diet.

Urinary stone disease and obesity: Different pathologies sharing common biochemical mechanisms

“…Several studies including patients with urolithiasis showed that higher BMI is significantly associated with a lower urinary pH level [1,5,9,12] . The reasons for a progressive decline in urine pH with increasing BMI in urolithiasis patients are not well defined.…”

“…The reasons for a progressive decline in urine pH with increasing BMI in urolithiasis patients are not well defined. Insulin resistance is one of the possible reasons [1] . Hyperinsulinemia and insulin resistance are more frequently observed in obese patients due to higher incidence of diabetes mellitus [3] .…”

“…The prevalence of urolithiasis requiring medical or surgical treatment is 5%-10% and increasing worldwide [1] . Urolithiasis is a multifactorial disease and it has previously been speculated that there is an association between urolithiasis and obesity [1][2][3][4][5] .…”

“…Urolithiasis is a multifactorial disease and it has previously been speculated that there is an association between urolithiasis and obesity [1][2][3][4][5] . Recently, a common pathophysiology has been advocated for both diseases, since several investigations have mentioned that the prevalence of urolithiasis has been increasing in parallel with obesity [2,3,6] .…”

A population-based study on the association between urinary calculi and kidney cancer

“…17 Previous studies have speculated that the mechanisms underpinning this association maybe involve the chronic irritation and infections related to UC. 18 The irritation and infections would cause inflammatory cells, (including neutrophils, macrophages, dendritic cells, mast cells) and lymphocytes at the damage site. The lymphocytes would then secrete a large number of cytokines and chemokines which promote the growth of neoplastic cells and contribute to the onset and progression of cancer.…”