Estrogen Rather Than Testosterone Might Be The Key To Libido

Common and accepted medical belief was that testosterone was associated with libido.  This was due to an association with low T and low libido.  But those of us in the field of men's health recognized that low T did not tell the entire story.  While some men with very low T AND low libido reported improved libido with normalized T levels, the improvements were inconsistent as best and not linear in nature.  By that I mean that after a certain T level was reached, further increases in T did not result in further improvements in libido.

Estrogen: Estrogen and Testosterone are intimately related.  Estrogen in fact comes from testosterone via conversion by aromatase, an enzyme.  Men with low T will also have low E levels and increasing T levels with medication will also increase E levels. Rising E levels in a man on testosterone therapy can cause gynecomastia, which is breast development.  As gynecomastia is an adverse outcome, doctors that do TRT monitor E levels and treat rising E with an aromatase inhibitor like Anastrozole.  I used to do this as well, and still do but much less often than in the past.  Why?  Because I noticed that some of my men on Anastrozole began complaining of dimished libido.  Research studies presented at this AUA14 supported what I noticed several years ago.

Conclusion: estrogen and testosterone are linked and both are needed for libido, but estrogen might be the more important of the 2 hormones in relation to libido.  More studies are needed.

Thanks,
Dr Schoor