The Associations Between Cigarette Smoking And Testosterone Levels In 2021 Chinese Men Of Han Nationality: Results From The Fangchenggang Area Male Health And Examination Survey (FAMHES)

Introduction. Previous studies have reported that low testosterone levels may lead to an increased risk of mortality. As cigarette smoking is a major health problem and highly prevalent among men in most cultures, research studies have also reported the effects of cigarette smoking on testosterone levels in men; however, results reported from these studies are conflicting.Aim. This study aimed to examine the associations of cigarette smoking and serum levels of sex hormone-binding globulin (SHBG), total testosterone (TT) and free testosterone (FT) in a large male population. Methods. Data from 2,021 men (989 nonsmokers and 1032 smokers), in the age range of 20-69, were collected from the Fangchenggang Area Male Health and Examination Survey using an in-person interview and self-administered questionnaires, from September to December in 2009. Weight and height were obtained and body mass index (BMI) was calculated. Blood samples were drawn for determination of plasma glucose levels and serum levels of total cholesterol, triglycerides, albumin, luteinizing hormone (LH), estradiol, TT and SHBG FT was calculated from values of TT, SHBG, and albumin.Main Outcome Measures. Tobacco exposure was measured using pack-years. We primarily evaluated the influence of smoking on circulating levels of SHBG, TT and FT in 2021 men.Results. Smokers have significantly elevated TT and FT levels as compared with nonsmokers, albeit following stratification according to age, body mass index (BMI), triglycerides and alcohol consumption, respectively. Interestingly, both TT (r=-0.083, P<0.001) and FT (r=-0.271, P<0.001) levels were significantly and negatively correlated with tobacco exposure among male smokers. We also found that smoking was an independent factor influencing both TT (unadjusted odds ratio (OR)= 1.64,95%CI:1.33-2.01, P<0.001; adjusted OR=1.69,95% CI: 1.34-2.13, P<0.001) and FT (unadjusted OR=1.32,95% CI:1.08-1.61, P=0.007; adjusted OR=1.27,95% CI:1.00-1.61, P=0.050) levels, based on multivariate logistic regression models prior to and after adjusting for age, BMI, fasting blood glucose, triglycerides, alcohol consumption and estradiol. Smoking was not an independent predictor of SHBG level even after adjustment for confounders in multivariate regression model (P> 0.05), although a positive association between increasing pack-years and SHBG level was observed (r=0.174, P< 0.001).Conclusion. In this study, smoking had a positive and independent effect on TT and FT levels, and the SHBG level was positively associated with increasing pack-years; however, no significant difference was observed between smokers and nonsmokers. More research is necessary to elucidate biological mechanisms that modulate these associations.