Hypernatremia
Hypernatremia refers to a condition in which the blood sodium level is too high (usually >145mmol/L) and the blood osmotic pressure is too high. Except for some special cases (such as excessive infusion of liquids containing too much sodium salt), this disease is mainly caused by water loss, sometimes accompanied by sodium loss, but the degree of water loss is greater than that of sodium loss. This disease often causes a decrease in intracellular water, which is due to the high extracellular osmotic pressure that can absorb intracellular water out of the cell; therefore, the blood volume does not decrease at the beginning, but it can still decrease in the late stage when it is serious.