Hypertonic dehydration, also known as primary dehydration or hypernatremia with reduced extracellular fluid, is characterized by more water loss than sodium loss, a serum sodium concentration of 150 mmol/L, and a plasma osmolality of 310 mOsm/L. When there is more water deficiency than sodium deficiency, the osmolality of extracellular fluid increases, antidiuretic hormone secretion is increased, renal tubular reabsorption of water is increased, and urine output is decreased. Aldosterone secretion increases, and sodium and water reabsorption increases to maintain blood volume. If water deficiency continues, the osmolarity of extracellular fluid increases further, intracellular fluid moves to the extracellular level, and eventually the degree of intracellular water deficiency exceeds that of extracellular fluid deficiency, which can eventually lead to brain cell dehydration and cause brain dysfunction. Patients with more water loss than sodium loss and high serum sodium concentration should not eat too spicy food, smoke less and drink less in the future. More should not eat too salty food. The following foods are recommended to eat less or not: 1, doughnuts: belong to fried food, high fatty acid content, and belong to the trans fatty acids, is not conducive to cardiovascular health. 2, bacon: is too salty food, which can cause the accumulation of salt in the body to increase the osmotic pressure, resulting in increased hyperosmolar symptoms, and even induce hypertonic shock. 3, cake: belongs to the high fat food, sugar and fat cold are high, is not conducive to intestinal evacuation is also not conducive to intestinal absorption of nutrients, should be avoided.