How Can You Say Testosterone Doesn’t Cause Hair Loss?
Hi Dr. Rassman!
First of all I would just like to thank you for a really good blog, I am a frequent reader and very much appreciate the time you put into it. I have read several times that you say that testosterone does not cause hair loss. However in theory I believe this is wrong, but I would also like to hear what you have to say about it in practice:
As you most certainly do know, testosterone and DHT bind to the same receptor – generating the same type of response. Therefore they both have the potential to cause hair loss. However, as DHT is more biologically active and binds with more affinity to the receptor, it is seen as the main culprit in hair loss. And as long as a person has normal DHT levels, the testosterone probably does not play a big role in hair loss.
But in a person with aggressive hair loss who blocks most of the conversion from testosterone to DHT with finasteride or maybe even dutasteride. Wouldn’t it be fair to assume that the testosterone (which will also be somewhat elevated when on these meds) actually contributes to the continuous loss while on these medication?
And that this could, in fact, explain how a persons hair loss can actually progress even though they might be blocking 90-something % of their DHT with dutasteride? Any input on this will be highly appreciated.
It is a mixed bag, since testosterone is converted by the liver to dihydrotestosterone (DHT), which then gets to circulate in the blood stream. Increasing testosterone levels will increase DHT as well, so which is the cause of balding on those people with genetic balding?
We can not really separate what is happening neatly as you described, as the human body is a “bag” of chemicals mixed together. I realize how elegant that sounds, but that’s the most simple way to describe it. If testosterone levels rise, DHT levels also rise and in this bag of chemicals (the human body) any change in testosterone will absolutely impact DHT levels comparably.
Thank you for taking the time to answer my question Dr. Rassman. However I am not sure you are correct about testosterone being converted to DHT in the liver.
As far as I know 5 ar type 2 (the enzyme that catalyzes the conversion) is not present in the liver, but it is present in the follicles and almost all conversion is done in the periferal tissue.
Eli:
To the best of my knowledge your endocrinologist is wrong, as I stated earlier that testosterone and DHT both bind to the same receptor – only that DHT binds with a high affinity. Therefore anything that testosterone does, DHT will do with an increased strength. Therefore it just does not make sense that testosterone would cause frontal balding and not DHT when DHT is just as present in the front of the scalp as in the crown area.
Eli: Also, when inhibiting the enzyme 5-alpha-reducatse the testosterone levels do rise slightl but this is because there will be less testosterone being converted to DHT and therefore this is a case when raised testosterone will not lead to raised DHT.