Hypernatremia is too much sodium (usually> 145mmol / L) in blood and with increase of blood pressure. Few exceptions (including the importation of too much liquid too much sodium, etc.), the disease is mainly caused by water loss, sometimes accompanied by loss of sodium, but sodium loss is greater than the degree of water loss. The disease often reduced intracellular water, extracellular This is because of the high intracellular osmotic pressure of water can be sucked into extracellular; therefore decrease blood volume does not start, but can reduce the serious late. Hypernatremia: that is, hyperosmolar dehydration, characterized by the body to reduce the total amount of sodium, and higher serum sodium concentrations. Hypernatremia followed by renal excretion of sodium reduction and the result of excessive sodium intake.