Xia BW, Zhao SC, Chen ZP, et al. - A total of 506 ostensibly healthy men who underwent routine health check-ups were enrolled in this study in order to examine the underlying influence of metabolic syndrome (MetS) on serum prostate-specific antigen (PSA) levels and to investigate the association between the major pathogenic factors of MetS and serum PSA levels. When concurrently adjusting for age, BMI, prostate volume and high-density lipoprotein cholesterol, serum insulin levels and SHBG levels were inversely related to serum PSA levels, and testosterone levels were positively associated with serum PSA levels. In multivariate regression models, serum insulin levels and serum SHBG levels were significantly related to serum PSA levels. Thus, among the major pathogenic factors of metabolic syndrome, the most important contributors to the reduction in serum PSA levels could be insulin resistance, and sex hormone changes.