No evidence for higher testosterone in black compared to white adolescent males

Racial/ethnic differences in serum sex steroid hormone concentrations in US adolescent males. Cancer Causes & Control. April 2013, Volume 24, Issue 4, pp 817-826

OBJECTIVE: Contrary to the hypothesis that the racial/ethnic disparity in prostate cancer has a hormonal basis, we did not observe a difference in serum testosterone concentration between non-Hispanic black and white men in the Third National Health and Nutrition Examination Survey (NHANES III), although non-Hispanic black men had a higher estradiol level. Unexpectedly, Mexican–American men had the highest testosterone level. Next, we evaluated whether the same patterns are observed during adolescence, the time of prostate maturation.

METHODS: We measured serum testosterone, estradiol, and sex hormone-binding globulin (SHBG) by immunoassay in 134 males aged 12–19 in NHANES III. Mean concentrations were compared by race/ethnicity adjusting for age, Tanner stage, percent body fat, waist, physical activity, tobacco smoke, and the other hormones.

RESULTS: After multivariable adjustment, in the 12–15-year-old males, testosterone concentration was lower in non-Hispanic blacks than whites (p = 0.043), SHBG concentration did not significantly differ between the two groups. Mexican–Americans had the highest testosterone (versus non-Hispanic black: p = 0.002) and lowest SHBG (versus non-Hispanic white: p = 0.010; versus non-Hispanic black: p = 0.047) concentrations. Estradiol concentration was lower in non-Hispanic blacks (p = 0.11) and Mexican–Americans (p = 0.033) compared with non-Hispanic whites. After multivariable adjustment, in the 16–19-year-old males, testosterone, estradiol, and SHBG concentrations did not differ between non-Hispanic blacks and whites. Mexican–Americans had the highest testosterone concentration (versus non-Hispanic white: p = 0.08), but did not differ from the other groups on estradiol and SHBG concentrations. In both age groups, these patterns were generally present, but less pronounced after adjusting for age and Tanner stage only.

CONCLUSION: In adolescent males, non-Hispanic blacks did not have a higher testosterone concentration than non-Hispanic whites, and Mexican–Americans had the highest testosterone concentration, patterns similar to adult males.

This sample is not large, and some of the statistical adjustments may be questionable. But others have also failed to find black-white differences in testosterone among adolescents in unadjusted NHANES data; nor were they seen in a larger study of adolescents,

Steroid hormones during puberty: racial (black-white) differences in androstenedione and estradiol--the Bogalusa Heart Study.

A large biracial cross-section of 1038 healthy children aged 6-18 yr with 519 blacks, 519 whites, 678 males, and 360 females was evaluated for Tanner stage and serum levels of androstenedione, dehydroepiandrosterone- sulfate, estradiol, progesterone, and testosterone. The anthropometric values of the blacks and whites were very similar at each Tanner stage with only minor differences in age, height, and weight related to an earlier onset of puberty in blacks. The hormones dehydroepiandrosterone- sulfate, progesterone, and testosterone did not exhibit any racial differences. Estradiol showed a significantly higher level among black males compared to white males (P 5 0.05) whereas androstenedione was significantly higher in both white males (P = 0.0001) and females (P I 0.01) compared with blacks.

9 comments:

Anonymous said...

Serum testosterone levels in healthy young black and white men.
http://www.ncbi.nlm.nih.gov/pubmed/3455741

Racial/ethnic variations in male testosterone levels: a probable contributor to group differences in health.
http://www.ncbi.nlm.nih.gov/pubmed/1621259

Running marathon halves testosterone level
http://www.ergo-log.com/marathontest.html

Peter Frost said...

The dataset is very questionable. It was analyzed for a previous publication by one of this study's authors (Rohrmann et al., 2007)

Some kind of bias is evident. In the same dataset, the 45-69 year old black men had higher t levels (5.62) than the 20-44 year old black men (5.35). Yet testosterone declines with age.

The authors used serum samples from the Third National Health and Nutrition Examination Survey (NHANES III). They used 1,479 samples that were still available out of an initial total of 1,998.

So 25% of the original samples were no longer available. That proportion corresponds to the reported incidence of Herpes simplex type 2 in an earlier study of the same NHANES-III serum bank. That earlier study stated that the infected samples were set aside for other tests.

In other words, the remaining serum samples were contributed by individuals who were less likely to contract STDs. That is not the sort of sample you should use for measuring mean testosterone, since high t individuals are more likely to have multiple sexual partners.

See my post on this topic:

http://evoandproud.blogspot.ca/2008/04/more-on-rohrmann-et-al.html

n/a said...

seantodroy,

The 1986 Ross et al. study is the only one I've ever seen claiming to find black-white T differences of that magnitude and direction. It's based on a small convenience sample and the authors explicitly set out to look for large black-white differences in testosterone, motivated by the idea that the existence of such differences might explain black-white differences in prostate cancer. They were not alone. This was a very common (though we now know almost certainly wrong) idea and numerous other cancer researchers looked and have continued looking for similar evidence. Decades later, nothing like the result claimed by Ross et al. has been replicated, suggesting it was a false positive.

The Ellis and Nyborg study as I recall claims to find something like 3% higher testosterone in black compared to white Vietnam veterans. Leaving aside the fact that obviously this is also not a perfectly representative sample, even if the reported difference is real and statistically "significant", it's very small and doesn't strike me as plausibly contributing significantly to explaining, e.g., racial differences in crime.

RE: the final URL, I was unaware we had an epidemic of American blacks training for marathons. My impression is that if anything environmental differences will tend to depress testosterone white American men relative to American blacks. I believe US black men consume more calories and more calories from fat, spend more time outdoors, and probably spend more time engaged in very light physical activity (walking) while spending less time actively pursuing endurance exercise.

n/a said...

Peter,

"Some kind of bias is evident. In the same dataset, the 45-69 year old black men had higher t levels (5.62) than the 20-44 year old black men (5.35). Yet testosterone declines with age."

As I recall, the source of this "bias" was obvious: the numbers were adjusted for age.

Mazur looked at the same data without adjustments, and his plot show testosterone declining with age (and extremely minimal black-white differences in those under 30).

"That earlier study stated that the infected samples were set aside for other tests."

This was your theory. I never saw anything to actually support this. Looking at the pdf you link to in your blog post, I'm still failing to see any actual confirmation that any samples were excluded for the reason you suggest.

Anonymous said...

I remember seeing some studies that suggest that, while testosterone and free testosterone levels may show statistically insignificant differences between races, sub-Saharan-derived black American populations have higher levels of a reductase enzyme that works to convert testosterone into its more potent DHT form. Basically, this means that blacks process testosterone at greater rate/volume(?) but they burn out their testosterone/free testosterone production sooner than do non-blacks. On the opposite end of the spectrum, Asians (even though they may have and produce comparable levels of testosterone) do not produce the same amount of the reductase converter. The result is that blacks behave in a more testosterone-driven way, whereas Asians behave in a less testosterone-driven way. This discrepancy, if true, would seem to square the anecdotal evidence and older biological studies (e.g. Ross et al, 1986) with the apparent findings that testosterone rates are stable across races.

Can't remember where I read that study, but a bit of searching should probably turn it up.

Lewis Griffin said...

I also found some data from the NHANESIII study in PDF form.

press.endocrine.org/doi/pdf/10.1210/jc.2007-0028

The age adjusted data in table 2 shows that non-hispanic blacks have higher testosterone levels than non-Hispanic whites, and Mexican Americans. When the adjustments are made Non-Hispanic blacks still have higher testosterone levels than Non-Hispanic whites, but Mexicans pull ahead of both. The question is how relevant are the after-adjustment numbers? Those adjustments, by design, are going to even things out. Maybe Mexican American have naturally higher testosterone than blacks, and whites, or maybe they do not, and that would partly explain why they are more likely to be smaller, less likely to consume alcohol, and more likely to have higher a percentage of body fat. The adjustment can be argued but the data shows that blacks have higher testosterone than white, and Mexican Americans. Blacks still have higher testosterone than whites when the adjustments are made. Keep in mind that this is a study that you cited in order to prove your point.

n/a said...

The black and white numbers are similar whether they're adjusted only for age or for multiple variables. The black-white difference isn't statistically significant either way, and in absolute terms it's less than 3%. A difference like that, even if real, could not begin to explain, e.g., racial differences in criminality.

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