Metabolic Abnormalities and the Risk for Recurrence in Obese Patients with Urolithiasis / 대한비뇨기과학회지

ABSTRACT

PURPOSE: Recent studies have suggested an increased prevalence of urolithiasis with obesity. This study aimed to assess the influence of obesity on urinary metabolic abnormalities and the recurrence of stone. MATERIALS AND METHODS: We analyzed 802 consecutive stone formers(SF first-time SF=501, recurrent SF=291) who underwent a comprehensive metabolic evaluation that included blood chemistry tests and a 24-hour urinary examination, as well as determining the body mass index(BMI). The BMI was categorized into the non-obese(BMIor=25kg/m2) according to the re-defined Western Pacific Region WHO criteria on obesity(WPRO). All possible risk factors such as age, gender, BMI, the clinical characteristics and the metabolic parameters were compared between both groups. Among them, 184(22.9%) patients had been followed up for more than 24 months or they recurred during the follow up(mean 56.0, median 58.5, range 7.0-140.0) and they were examined for the risk of stone recurrence by performing multivariate Cox regression analysis. RESULTS: Obesity was significantly associated with the increased urinary excretion of sodium, calcium and oxalate(p<0.05, respectively). The urinary pH value showed inverse correlation with obesity(p=0.012). Urinary metabolic abnormalities were more common in the obese SF patients than the non-obese SF patients(p=0.003). Obesity was significantly associated with the stone recurrence rate(p=0.009). Cox regression analysis revealed that obesity was a strong predictor for recurrent stone formation(adjusted HR=2.384 95% CI 1.372-4.143, p=0.002). CONCLUSIONS: Our results reveal that obesity is highly associated with metabolic alterations and urinary stone recurrence. Therefore, weight control might be considered as one of the preventive measures against recurrent stone formation.