Wagoner AL, Tarbell SE, Shaltout HA, Diz DI, Weese-Mayer DE, Fortunato JE. Chronic nausea and orthostatic intolerance: Diagnostic utility of orthostatic challenge duration, Nausea Profile Questionnaire, and neurohumoral measures. Neurogastroenterol Motil. 2018 11; 30(11):e13433.