The normal value of sodium in the human body is 135-145mmol/L. Sodium is one of the most important ions in the human body. Sodium is one of the most important ions in the body and plays an important role in maintaining electrolyte balance and osmotic pressure balance. Any increase or decrease in blood sodium will have a significant effect on the body. The normal value of sodium in the human body is 135～145mmol/L, which can be known by the electrolyte level of laboratory tests. 1. A sodium concentration of less than 135 mmol/L is hyponatremia. If it is less than 120 mmol/L and is decreasing rapidly it is a danger sign. Patients with hyponatremia are seen to have generalized fatigue, apathy, blurred vision, headache, muscle cramps, dyskinesia, nausea, and convulsions. It is common in cases of decreased food intake, nausea, vomiting, diarrhea, hypoadrenocorticism, and inappropriate secretion of antidiuretic hormone. 2. Blood sodium higher than 145mmol/L is hypernatremia, which is mostly seen in excessive water loss, profuse sweating, or hyperadrenocorticism, aldosteronism or cerebrovascular accidents. With high sodium levels, patients initially present with agitation, malaise, irritability, nausea, vomiting, and muscle tremors. When blood sodium rises sharply above 160 mmol/L, mental status changes can occur, with lethargy, seizures, and even coma. Increase or decrease of blood sodium should be clinically clarified and aggressively treated.