Hello Welcome in H.C.M. I have gone through your query regarding role of saline nasal spray to prevent nasal bleeding in grave s disease. In grave s disease the mucosal lining gets dry and thus there is fair chances of crusting. In nasal mucosa crusting irritates the nasal cavity and removal of crust may result in nose bleed. To avoid it nasal cavity is sprayed by saline to hydrate it and to prevent crusting in nasal cavity. As an alternative remedy one may use liquid paraffin or glycerin. I hope above had clarified your query. Regards.