A 20 year-old Caucasian female with a past medical history significant only for occasional headaches and anemia presents with a chief complaint of increasing thirst for two weeks. The patient was in her usual state of health until approximately two weeks prior to admission when she noted the gradual onset of increasing thirst and began drinking more and more water over the next few days. Her thirst increased to the point where she drank an estimated 18 liters of fluid during the 24 hours prior to admission. This thirst was accompanied by frequent urination, which would often awaken her during the night and she noted her urine to be very clear. These symptoms began within a few days of a vaginal yeast infection, for which she was treated with one dose of fluconazole. She denied any other symptoms during this episode.