PRN in Any Field. You can be a PRN employee in any medical-related field. Many PRNs are therapists, nurses or nursing aides. But many other medical areas also use PRN employees to fill in as needed as laboratory workers, therapists, sleep technicians or other medical specialists. You'll Have Flexibility A PRN often is an employee who wants to continue to work in a chosen field but does not want to commit to a regular, full-time schedule. If you're a PRN employee, you can accept or reject an offered assignment. This gives you the freedom to use the time to attend a child's sporting event or school program or have dinner with a spouse.