The causes of low sodium in lung cancer patients usually include excessive sodium consumption, associated cancer syndrome, etc., which need timely medical treatment once discovered. 1. Excessive consumption: As lung cancer patients are bedridden for a long time, with poor appetite and lack of nutrition, the body is in a state of malignant disease and hypoproteinemia, resulting in excessive sodium consumption, hyponatremia is easy to occur, and its symptoms can be manifested as slow reaction and weakness. 2. Accompanying cancer syndrome: Carcinoid tumor in lung cancer may cause accompanying cancer syndrome, which can cause hypokalemia and hypochloremia, and if the patients can not get effective treatment for a long time, it may also produce persistent hyponatremia, and in serious cases, it may also cause cerebral edema and lead to death. It is suggested that patients should consult the doctor in time and actively cooperate with the doctor to avoid delaying the condition.