Avodart and hair loss, a question

Don has been on finasteride or dutasteride/Avodart for a while. When he first started taking it, his hair (which was falling diffusely but not profusely) stopped falling. In the past three months, however,it has been falling quite heavily again. I am wondering if this means it isn't blocking his 5-alpha reductase/preventing the conversion of T to DHT for whatever reason. Any opinions? I will ask Dr. Myers this question when we see him but am wondering if anyone else has experienced this. This morning, I thought he'd installed a carpet in the powder room while I wasn't looking.

Yes, Allen, but the two doctors there said he will not have diffuse hair loss, just "maybe" a strip of falling hair confined to where they targeted the Ra. (A very small area of the skull base, apparently.) It is no issue for him as he has thick hair. I just find it puzzling.