It depends on the da (density altutude) at each elevation, but yes you will probably have a shift. You need to go to jbm and print out some da range cards. Lindy has great instructions on how to do that on his website.
If you want an answer to your basic question, set up your load in the JBM calculator linked there, and you can see what each 1000 foot increment - or whatever you want - does.