Possible Relationship between Metabolic Syndrome Traits and Nephrolithiasis: Incidence for 15 Years According to Gender

PURPOSE To analyze the independent effect of metabolic syndrome (MS) on nephrolithiasis (NL) despite differences in gender compared with the known lithogenic factors. MATERIALS AND METHODS From 1995 to 2009, 40,687 Koreans were enrolled in the study and observed for the development of NL at a health promotion center. The examination included anthropometric and biochemical measurements as well as kidney ultrasonography. A student's t-test or chi-square test was used to characterize the participants and a standard Cox proportional hazards model was used to calculate the adjusted odds ratio of lithogenic risk factors in the NL model. RESULTS The mean age of the study cohort was 44.9 years (range, 13-100 years), and 22,540 (55.4%) of the cohort was male. The incidence of NL was 1.5% (609 participants), with males exhibiting a higher incidence than females (1.9% vs 1.0%, p<0.01). Among the total cohort, MS as well as each trait of MS were risk factors for NL. In males, high body mass index (BMI), high blood pressure, and abnormal glucose metabolism were significant lithogenic factors, whereas in females, lithogenic factors included only high BMI and abnormal glucose metabolism. CONCLUSIONS MS is a significant lithogenic factor compared with other lithogenic factors. There was a correlated change in the prevalence of MS and NL and MS traits in Korea.