The weighted mean age was 41.5 years (). The study population consisted of 78.9% non-Hispanic white, 9.1% non-Hispanic black, 5.0% Mexican-American, and 7.1% men of other race/ethnicities. The geometric mean hormone concentrations were 5.27 ng/mL for total testosterone, 0.106 ng/mL for free testosterone, 36.0 pg/mL for total estradiol, 0.919 pg/mL for free estradiol, 34.4 nmol/L for SHBG, and 12.0 ng/mL for androstanediol glucuronide.
Selected Characteristics and Hormone Concentrations of 1,275 Adult Men Who Participated in the Third National Health and Nutrition Examination Survey (NHANES III)
In the multivariable-adjusted model, current smokers had higher concentrations of total testosterone (the geometric means were 5.42, 5.10 and 5.26 ng/mL in current, former and never smokers, respectively), free testosterone (0.110, 0.102 and 0.104 ng/mL), total estradiol (40.0, 34.5 and 33.5 pg/mL) and free estradiol (1.05, 0.878 and 0.844 pg/mL) than former and never smokers (all P≤0.05) (). Former smokers appeared to have lower concentrations of both total and free testosterone than never smokers, although the differences were not statistically significant (P=0.3 and 0.6, respectively). Concentrations of androstanediol glucuronide (P=0.2) and SHBG (P=0.7) did not differ by smoking status. However, a significant interaction was observed between age and smoking status and androstanediol glucuronide (P-interaction=0.01), such that older men (≥44 years) who were current smokers (never: 11.6 ng/mL; former: 10.5 ng/mL; current: 9.1 ng/mL) had lower androstanediol glucuronide than never smokers (P=0.06) (younger men <44 years: never: 12.7 ng/mL; former: 13.7 ng/mL; current: 13.2 ng/mL). Men currently actively exposed to tobacco smoke, as measured by cotinine, also had higher concentrations of testosterone, free testosterone, estradiol, and free estradiol compared with men unexposed (i.e., neither active, nor passive exposure) to tobacco smoke. Men passively exposed to cigarette smoke also had greater total testosterone (5.21 compared with 4.90 ng/mL, P=0.03) and free testosterone (0.104 compared with 0.096 ng/mL, P=0.005) concentrations than those unexposed to tobacco smoke. Compared with never smokers, men unexposed to cigarette smoke based on cotinine concentration had lower concentrations of total and free testosterone. This difference is likely due to the never smoker category consisting of men with both no exposure and passive exposure to tobacco smoke. Among current smokers, no dose-response relationship was seen between cigarettes smoked per day, pack-years smoked or serum cotinine and concentrations of total testosterone, SHBG, androstanediol glucuronide or free testosterone (all P-trend>0.4). However, higher daily number of cigarettes smoked, pack-years smoked and serum cotinine were all associated with greater concentrations of total estradiol and free estradiol (all P-trend≤0.06; ).
Adjusted Geometric Mean Hormone and Sex Hormone-Binding Globulin (SHBG) Concentrations and 95% Confidence Intervals by Measures of Cigarette Smoking in a Nationally-Representative Sample of Adult Men in NHANES III
In a sub-analysis, we re-defined current smokers as those who were self-reported current smokers and were active smokers based on cotinine concentration; never smokers were redefined as self-reported never smoker and had cotinine concentration in the no exposure range. Using these definitions, total testosterone (5.42 vs. 4.95 ng/mL; P=0.04), free testosterone (0.110 vs. 0.096 ng/mL; P=0.009), total estradiol (40.0 vs. 33.8 pg/mL; P<0.001) and free estradiol (1.05 vs. 0.84 pg/mL; P=0.001) concentrations were higher in current smokers than in never smokers, findings that were consistent with those seen when defining smoking status based on self-report only or based on cotinine only.
In the multivariable model, men with usual intake of at least one drink per day had lower concentrations of SHBG than men who consumed 0 to 6 drinks/week (31.5 vs. 34.8 nmol/L, P=0.01) (); the inverse trend was statistically significant (P-trend=0.01). The frequency of alcohol consumption was positively associated with total testosterone (P-trend= 0.08) and free testosterone (P-trend=0.06), although these associations were not statistically significant. An interaction (P-interaction=0.06) was observed between age and the frequency of alcohol consumption with total and free testosterone. Both total (P-trend=0.06) and free (P-trend=0.05) testosterone increased with an increasing number of drinks consumed per day among younger,(<44 years), but not older men (P-trend=0.4 and P-trend=0.3, respectively). No consistent patterns were seen between the amount of alcohol consumed, as measured by the 24-hour dietary recall, or the frequency of heavy episodic drinking and any of the hormones or SHBG. Additionally, no associations were observed between specific types of alcohol (beer, wine and liquor) and serum hormone and SHBG concentrations (data not shown).
Adjusted Geometric Mean Hormone and Sex Hormone Binding Globulin (SHBG) Concentrations and 95% Confidence Intervals by Measures of Alcohol Consumption in a Nationally-Representative Sample of Adult Men in NHANES III
In the multivariable model, men in the highest category of frequency of physical activity had higher concentrations of both total (5.42 vs. 5.05 ng/mL; P=0.003) and free testosterone (0.109 vs. 0.098 ng/mL; P=0.005) and lower concentrations of both total (35.2 vs. 38.1 pg/mL; P=0.009) and free estradiol (0.88 vs. 0.95 pg/mL; P=0.09) than those who reported no physical activity, although the trends in concentrations across activity levels were not statistically significant (). Age was found to modify the association between physical activity and both total and free estradiol (P-interaction=0.004), such that total and free estradiol concentrations decreased with increasing frequency of physical activity among younger men (<44 years; P-trend=0.03 and P-trend=0.03, respectively), but not older men (≥44 years; P-trend=0.7 and P-trend=0.5, respectively). In contrast, men who engaged in vigorous physical activity at least four times a week had higher concentrations of total estradiol than men who engaged in no physical activity (37.3 vs. 35.5 pg/mL; P=0.09). No associations were seen between total or vigorous physical activity and androstanediol glucuronide or SHBG.
Adjusted Geometric Mean Hormone and Sex Hormone-Binding Globulin (SHBG) Concentrations and 95% Confidence Intervals by Total and Vigorous Physical Activity in a Nationally-Representative Sample of Adult Men in NHANES III