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Testosterone: Difference between revisions
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→Secular decline in T-levels of Western men
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==Secular decline in T-levels of Western men== | ==Secular decline in T-levels of Western men== | ||
There has been a secular decline in male T levels in Western countries that is independent of factors such as population aging and increased obesity,<ref>https://academic.oup.com/jcem/article/92/1/196/2598434?login=true</ref> a finding which has lead to sensationalist headlines regarding rampant [[soyboy|feminization]] of men being driven by this factor alone. However, other longitudinal studies have found concurrent evidence that sex-hormone-binding globulin (SHBG), a protein that binds to testosterone and makes it inert in the body, has also been decreasing on a population and cohort level.<ref>https://academic.oup.com/jcem/article/92/12/4696/2597312?login=true</ref> | There has been a secular decline in male serum T levels in Western countries that is independent of factors such as population aging and increased obesity,<ref>https://academic.oup.com/jcem/article/92/1/196/2598434?login=true</ref> a finding which has lead to sensationalist headlines regarding rampant [[soyboy|feminization]] of men being driven by this factor alone. However, other longitudinal studies have found concurrent evidence that sex-hormone-binding globulin (SHBG), a protein that binds to testosterone and makes it inert in the body, has also been decreasing on a population and cohort level.<ref>https://academic.oup.com/jcem/article/92/12/4696/2597312?login=true</ref> | ||
If this finding proves robust, this reduction in SHBG would result in less negative feedback being exerted on men's hypothalamic-pituitary-gonadal axis (HPG axis), which would lead to the body downregulating T production as it essentially needs less to produce the desired effects. Meaning the secular decrease in T wouldn't be particularly relevant in driving any practical differences in population level masculinization. One reason why SHBG is lowering is likely due to increasing obesity, meaning that obese men would often have lower T levels (due to higher aromatization of T to estrogen, as the fat cells contain the aromatase enzyme<ref>https://pubmed.ncbi.nlm.nih.gov/11399122/</ref>) but would also be more sensitive to the testosterone they do produce. | If this finding proves robust, this reduction in SHBG would result in less negative feedback being exerted on men's hypothalamic-pituitary-gonadal axis (HPG axis), which would lead to the body downregulating T production as it essentially needs less to produce the desired effects. Meaning the secular decrease in T wouldn't be particularly relevant in driving any practical differences in population level masculinization. One reason why SHBG is lowering is likely due to increasing obesity, meaning that obese men would often have lower T levels (due to higher aromatization of T to estrogen, as the fat cells contain the aromatase enzyme<ref>https://pubmed.ncbi.nlm.nih.gov/11399122/</ref>) but would also be more sensitive to the testosterone they do produce. | ||
Serum testosterone levels are far less clinically relevant than levels of unbound (free) testosterone, so what is important to establish a real decline in T levels would be to prove that levels of free-testosterone are falling. | Serum testosterone levels are far less clinically relevant than levels of unbound (free) testosterone, so what is important to establish a real decline in T levels would be to prove that levels of free-testosterone are falling. | ||