A Physician Assistant (PA) is a health care licensed professional, or in the case of one employed by the federal government, credentialed, to practice medicine with physician supervision. As part of their comprehensive responsibilities, PAs conduct physical examinations, diagnose and treat illnesses and additional problems, order and interpret lab tests, counsel patients on preventive health care, assist physicians in surgery, and write prescriptions. Within the physician-PA relationship, physician assistants exercise autonomy in medical decision making and provide a broad range of diagnostic and therapeutic services. A PA’s practice may also include education, research, and administrative services.