Hyponatremia is a disease condition in which the concentration of sodium in the blood is lower than normal. One of the main causes of hyponatremia is insufficient sodium intake, such as long-term fasting, gastrointestinal diseases and malnutrition, which can all lead to hyponatremia. When hyponatremia occurs, most patients do not experience any discomfort when the disease is mild. In severe cases, a series of symptoms may appear, such as nausea, vomiting, weakness, fatigue, headache, irritability, and even blurred consciousness, and muscle weakness and convulsions, as well as seizures and even coma.