The age-testosterone relationship in black, white, and Mexican-American men, and reasons for ethnic differences

Recent studies give contradictory findings regarding testosterone levels in white, black, and Hispanic men. Here, I present a cross-sectional reanalysis of serum testosterone and sex hormone-binding globulin (SHBG) in 1637 males, aged 12-90, who participated in the morning examination of the Third National Health and Nutrition Examination Survey (NHANES III) during the year 1988-1991. Testosterone and SHBG in males are described precisely over the age range 12 to 90 years. Testosterone and SHBG are not notably different in white and Mexican-American (MA) males. In the age range 20-69 years, black men average 0.39 ng/ml higher testosterone than white and MA men (p < 0.001). The higher testosterone in black men is partly explained by low marriage rate and low adiposity.