Clinical symptoms of hyponatremia are poor, especially in patients with cerebral hemorrhage, they easily confused with symptoms of central nervous system (CNS) damage caused by cerebral hemorrhage such as confusion, seizure, coma... The reasons of hyponatremia and associatedfactors have not been clearly defined, but the results of many studies often suggest that the causes of hyponatremia are two syndromes: syndrome of inappropriate anti-diuretic hormone secretion (SIADH) and cerebral salt wasting syndrome (CSWS).