I believe he would have to be licensed in PA to prescribe tests.

"In Pennsylvania, only licensed healthcare practitioners are legally permitted to order laboratory tests. This includes physicians, physician assistants, nurse practitioners, and other healthcare professionals who have the authority to diagnose and treat patients.
As for DCs, their scope of practice primarily focuses on chiropractic care and manipulation of the musculoskeletal system. While they may have limited lab ordering rights related to their area of expertise, the extent of their authority to order laboratory tests may be more restricted compared to medical doctors."