What Causes Elevated AST Levels In Blood?

I m a 37 year old male and just got physical blood results back. Two things: 1. My AST (SGOT) is 45, which was flagged for being high. My ALT is 36. Should I be concerned? 2. My HIV 1/2 Ab Differentiation were both non-reactive but was recommended for HIV RNA testing, should I be concerned?