When brain cells are dehydrated by increased extracellular fluid osmolarity, it can cause a series of symptoms of central nervous system dysfunction, including drowsiness, muscle twitching, coma, and even death. It is hypertonic dehydration. The following is the differential diagnosis of this disease: isotonic dehydration: also known as isotonic dehydration. It refers to the loss of water and sodium in proportion to each other, and the osmolarity of extracellular fluid remains unchanged. However, if the degree is not serious and the kidney function is good, the body fluid can be maintained in an isotonic state through the regulating action of the kidney. In isotonic dehydration, the extracellular fluid is dehydrated, and the intracellular fluid does not change significantly because the osmotic pressure inside and outside the cell is equal, so there are only clinical signs of dehydration caused by the decrease of extracellular fluid, and there is no brain cell dehydration or edema. Hypotonic dehydration: It can cause water to move from extracellular fluid to intracellular fluid with relatively high osmolarity, causing cellular edema (such as cerebral cell edema) on the one hand, and further reduction of extracellular fluid and further aggravation of hypovolemia on the other. It can be seen that intracellular fluid is not lost or even increased in hypotonic dehydration, but mainly extracellular fluid is significantly reduced, which leads to decreased blood volume and peripheral circulation failure, often with venous collapse, decreased arterial blood pressure, and fine pulse rate. Hypertonic dehydration: Also called primary dehydration or hypernatremia with reduced extracellular fluid, characterized by more water loss than sodium loss, serum sodium concentration of 150 mmol/L and plasma osmolality of 310 mosm/L.