The Relationships Of Testosterone And Sex Hormone-binding Globulin With Metabolic Syndrome In Men

Background and Objective:Testosterone is the most important sex hormone for men, it participates in the regulation of metabolism of protein, fat and energy, while sex hormone-binding globulin (SHBG), a steroid hormone combination globulin, bound to TT with high affinity and regulates its biological availability and activities, thereby may affect the metabolism of energy and fat. Currently, there are many studies have explored the relationships of TT and SHBG with MetS, and shown total testosterone (TT) and sex hormone-binding globulin (SHBG) inversely associated with the prevalence of metabolic syndrome (MetS), but it is still controversial whether they associated with MetS independently of they each other and other risk factors of MetS. Meanwhile, much evidence also shown MetS is a risk factor of benign prostatic hyperplasia (BPH). Our present study tries to investigate the associations of TT and SHBG with MetS in a Chinese male population, and hope to provide the theory basis for prevention and control of MetS and BPH. Study Design and Methods:Our present cross-sectional study recruited participants from the Fangchenggang Area Male Health and Examination Survey (FAMHES) cohort, and2361parcitipants met our criteria and included this study finally. Trained physicians conducted a face-to-face interview to get the basic information of each participant. Height, weight, waist circumference (WC) and blood pressure (BP) were determined by trained personnel using a standardized protocol. Overnight fasting venous blood specimens were drawn by venipuncture. Triglycerides (TG), high-density lipoprotein cholesterol (HDL-c) and fasting blood glucose (FBG) were measured by enzymic method. Serum TT, SHBG and insulin were measured with electrochemilumines-cence immunoassay with the same batch of reagents. MetS was defined based upon the National Cholesterol Education Program Adult Treatment Panel Ⅲ (NCEP-ATP Ⅲ) guidelines for Asian Americans. Student’s t-test was used to compare continuous variables, pearson chi-square test was used to assess categorical variables. Variance analysis was used to compare the difference of sex hormones levels among different groups of samples. Spearman partial correlation coefficients of sex hormones and components of MetS were calculated. Logistic regression analysis was used to evaluate the ORs of the prevalence of MetS in different quartiles of sex hormones and determine whether TT and SHBG associated with MetS independently of they each other. Potential confounders included age, smoking status, homeostasis model assessment of insulin resistance (HOMA-IR) and body mass index (BMI). Data processing and statistical analyses were performed with SPSS17.0(SPSS, Chicago, IL). All statistical assessments were2-sided, and p value<0.05was considered statistically significant.Results:The prevalence of MetS was12.7%. Mean levels of TT, bioavailable testosterone (BT), free testosterone (FT) and SHBG were20.66±1.35nmol/l,9.57±1.34nmol/l,39.07±1.34pmol/dl and37.75±1.60nmol/1, respectively. Subjects with MetS had significant lower serum TT, BT, FT and SHBG level than subjects without MetS, and serum levels of TT, BT and FT significantly decreased with age, while SHBG increased (all P<0.001for trend). TT and SHBG positively correlated with HDL-c and negatively with BP, FBG, TG, WC, and BMI, while BT and FT negatively correlated with FBG, TG, WC, and BMI after adjusting for age (all P<0.001). All of these sex hormones levels lower in men with MetS and decreased with the increasing numbers of MetS components (all P<0.001for trend). In a multivariate analysis, increased ORs for MetS were observed from the highest to the lowest quartiles of sex hormones levels, after adjustment for age, smoking, HOMA-IR and BMI gradually, all of the ORs decreased substantially, but statistically significant difference still existed. Another multivariate regression analysis shown that both TT and SHBG levels were inversely associated with the prevalence of MetS independently of they each other, age, smoking, HOMA-IR and BMI, while BT and FT inversely associated with the prevalence of MetS, these associations persisted even further adjusted for age, smoking, HOMA-IR, but disappeared if further adjused for BMI.Conclusion:Levels of TT, BT, FT and SHBG were lower in men with MetS than those without MetS. Both TT and SHGB independently and inversely associated with the prevalence of MetS in our population.