If I understand, and my apologies if I don't. Spiro is used in females to treat MPD due to excessive androgen production in the woman affected. Basically by blocking excessive Testosterone production in them.
If your testosterone levels are normal for a woman it won't have any effect. As you are post-op your T production should be that of a normal female your age. So in a summary, Spiro helps to stop MPB in natal females who are producing excessive T, by blocking T production, not by stimulating hair growth. Since your T level should be low it won't have any effect. But talk to your endo to see if your T levels have increased for some reason.
Hope that makes sense
Cindy