Its not low androgen that causes bone loss but LOW ESTROGEN (even in men).
Shhs, I just wish this myth would be soundly defeated once and for alll.
In men, part of the free T (unbinded to T receptors) is aromatised into E, which helps
ward against bone loss. Since T levels decline very slowly, E remains usually high enough
to prevent bone loss until the late 60's.
In women, crashing E levels in the mid 40's lead to increase mid fat accumulation and
increased risk of osteoporosis. The conversion of unbinded free T from the adrenals
by fats is not enough to help the bones. Ironically, in a women, an anti-androgen
would actually help the bones by increasing the level of T available for conversion
to T (since T could not bind to T receptors) and the adrenal level of T is not
controlled by the free blood level of T.
I men, using an anti-androgen increases free T (unbinded T) and thus the pituitary
gland instructs the testes to reduce T output. If the anti-androgen level is high
enough, there will always be too much unbinded T produced by the testes and
through a retroactive loop, the testes output will be
eventually reduced towards zero.
Eventually, the unbinded T levels become too low for a proper conversion to E
(this is particularly true if someone is thin and thus have a low level of aromatased
activity). So a man taking anti-androgen and nothing else will soon be
in the same situation as a post menauposal women taking an anti-androgen.
