As far as I know, there are no states where it is possible to challenge RN boards. All states use NCLEX as their state board exam, and one of the requirements to take NCLEX is to have either an associate's or bachelor's degree in nursing from an accredited school of nursing. There is quite a bit of schooling required to be an RN that is not covered in LPN school- detailed assessments, more in-depth peds/ob classes, more advanced pharmacology & pathophysiology classes, etc...