Hyponatremia is a condition in which the body’s serum sodium concentration is below the lower normal limit of 135 mmol/L, also known as hyponatremia. The occurrence of hyponatremia may be related to reduced sodium intake, excessive loss, and water intoxication. 1. Reduced intake: for example, loss of appetite or gastrointestinal tract there are some diseases that affect the absorption of sodium, when the intake of sodium ions is too small, the serum sodium content is rapidly reduced, the intracellular and extracellular osmotic pressure loses the original balance, thus causing hyponatremia. 2. Excessive loss: one is excessive renal loss, mostly due to the patient’s use of diuretics, such as spironolactone. There is also adrenocortical insufficiency, which may lead to hyponatremia. The other is excessive gastrointestinal loss, mostly due to severe vomiting and diarrhea. 3. Water intoxication: It may be related to abnormal secretion of antidiuretic hormone and excessive short-term water intake. It leads to water retention in the body, causing a decrease in plasma osmolality and an increase in circulating blood volume, and a condition of dilutional hyponatremia. When hyponatremia occurs, it is recommended to consult a doctor in time, follow the doctor’s instructions for further examination, clarify the cause with the doctor’s help, and carry out targeted treatment or therapy.