I used dostinex 6-7 months after a very mild tren/deca/winstrol cycle, because i was getting no results on pregnyl/dufine.
Blood test showed prolactin levels on the high side, but in the "normal" range.
Half a pill of dostinex twice a week did wonders for me. After 8 weeks prolactin levels dropped and remained low.
It is my belief that prolactin can rise, even on cycles without tren or deca.
I also believe that prolactin (and other hormones) de-regulate during the cycle, and don't return to previous levels, even after years off steroids.