Serum sodium refers to the presence of sodium ions in the blood, and in blood chemistry it refers to the concentration of sodium ions in the serum, with a normal reference range of 135-145 mmol/L. When there is significant electrolyte disturbance, especially in hypernatremia, severe cerebral edema, etc., can occur, and neurological dysfunction requires active sodium-lowering therapy, the most common clinical approach is intravenous glucose drip or hemofiltration and other treatments. When there is obvious hyponatremia, patients can appear obvious weakness, poor nausea, etc., most commonly in the case of nausea, vomiting and other rapid decrease in blood volume, also can be seen in lung malignant tumors, such as oat cell carcinoma, etc., to further identify the cause of the disease, symptomatic treatment.