A 17-year-old girl was admitted to the hospital with a 10-day history of bilateral flank pain radiating to the back, associated with low-grade fever without urinary symptoms. She had no significant medical history and denied exposure to any medications in the recent past. Findings on physical examination included an oral temperature of 100°F, pulse rate of 90 beats/min, and blood pressure of 100/70 mm Hg without postural decrease on sitting up. She had conjunctival pallor. The chest and cardiovascular examination had unremarkable findings.