Early symptoms for hypernatremia is thirst, reduced urine, nausea and vomiting and weak increase in body temperature; have signs with lost water. Symptoms appeared in the late loss of brain cells, such as irritability, lack of bowel or mental, sleepiness or epileptic convulsions and coma-like episodes; signs have increased muscle tone and hyperreflexia, etc. In severe cases, death. Familial idiopathic hypernatremia primarily on the performance of clinical hypertension and hypokalemia with similar aldosteronism. Sense of thirst because of the central threshold of osmotic pressure increase caused by idiopathic hypernatremia generally no obvious clinical manifestations. Excessive water loss caused by hypernatremia often missing sodium loss more than its clinical manifestations are often covered by water.