A 17-year-old female presents to your office with complaints of generalized weakness and fatigue. She has needed to take a nap to get through the day when able or else goes to bed about 8:00 p.m., which is not typical for her. She is a senior in high school on the A honor roll and works part-time as a server, but she is always tired. She does not take any medications. 1. What are your immediate top three differentials and why?