Objective: To test the hypothesis that lower endogenous testosterone levels are associated with higher blood pressure, left ventricular mass, and left ventricular hypertrophy.
Design: Population-based cross-sectional study.
Methods: Sex hormone levels, measured by immunoassay, anthropometric measurements and resting blood pressure were studied in 1548 men aged 25-84 Years; echocardiography was completed in 1264 of these men. Partial correlations and multiple regressions were used to estimate the associations between sex hormones, blood pressure and left ventricular mass by height. Analyses of variance and covariance were used to compare men with categorical hypertension and left ventricular hypertrophy.
Results: In age-adjusted partial correlations, total testosterone and sex hormone-binding globulin (SHBG) were each inversely associated with systolic blood pressure (SBP) (P<0.001). Men with categorical hypertension (SBP> or =140 or diastolic blood pressure (DBP)> or =90 mmHg) had lower levels of total and free testosterone and SHBG before (P<0.001, P=0.011 and P<0.001, respectively) and after (P<0.001, P=0.035 and P=0.002, respectively) adjusting for body mass index (BMI). Total testosterone and SHBG were each inversely associated with left ventricular mass (P<0.001), and men with left ventricular hypertrophy had significantly lower levels of total testosterone (P=0.042) and SHBG (P=0.006); these associations were no longer significant after adjusting for BMI.
Conclusion: The results of the present study are consistent with the hypothesis that lower levels of testosterone in men are associated with higher blood pressure, left ventricular mass, and left ventricular hypertrophy. The reduced associations after adjusting for BMI suggest that the association of low testosterone levels with blood pressure and left ventricular mass is mediated by obesity.