I've found my hair thinning stopped since using HRT (Estrogel and Utrogestan), not just on my head but my pubes too! I was getting rather sparse down there. It's not back to its full former glory yet, though that could be a blessing in disguise as it was always really really thick and hard to manage, it's quite normal now.
I only started taking HRT recently so am not sure if the hair loss was a result of my own natural hormones declining or a severe bout of stress I went through last year, either way it's good to see it slowly reversing.
All that said, I have been taking a number of different supplements (for other reasons) so I can't definitely say the reverse is down to the BHRT but I'd put my money on that one.
GG x