Hyponatremia is a pathological condition in which the serum sodium concentration is less than 135 mmol/L. The normal serum sodium concentration in the body is 135 to 145 mmol/L. The normal serum sodium concentration is 135~145mmol/L. Hyponatremia can be manifested as headache, nausea, vomiting, drowsiness, fatigue, restlessness, numbness of hands and feet, etc., which should be taken seriously enough to consult the doctor in time to check the cause. Hyponatremia is a disease caused by water and electrolyte disorders in the body, and the common causes include irrational use of diuretics, excessive water intake, vomiting and diarrhea, extravasation of sodium from the blood in case of extensive burns, and prolonged gastrointestinal decompression. Tests generally needed for hyponatremia include physical examination, electrolyte examination, plasma osmolality examination, and if necessary, blood glucose, blood lipid, protein, liver function index, thyroid hormone and other tests, in order to clarify the specific causes of hyponatremia. The treatment of hyponatremia should be based on the type, degree and cause of hyponatremia, and adopt different methods to give targeted and personalized treatment. The main principles of treatment are: eliminating the cause, treating the primary disease, restricting water intake, supplementing sodium ions to correct hyponatremia, symptomatic treatment and dealing with complications.