Because men are supposed to have some. An enzyme called aromatase converts a portion of testosterone into estradiol (the main estrogen), and that estradiol isn't a contaminant - it's essential, supporting bone density, mood, cognition, libido and more in men.
So the goal on TRT is never "zero estrogen"; it's the right balance. This surprises men who assume estrogen is purely a female hormone or purely a problem - it's neither, and understanding that prevents a lot of self-inflicted mistakes.


