Some lung cancers cause low potassium in patients. The cause of lung tumors is not clear, and may be related to factors such as heredity, exposure to ionizing radiation and long-term smoking. Some lung cancers, especially small-cell lung cancer, will secrete some hormones, such as antidiuretic hormone, which will lead to excessive discharge of potassium in urine, causing low potassium. Chemotherapy and targeted therapy will also cause vomiting, diarrhea and other adverse reactions, which will lead to potassium loss and low potassium. Low potassium may also occur in late-stage patients due to loss of appetite and reduced gastrointestinal function, which may affect potassium intake or absorption. Low potassium can cause gastrointestinal symptoms, such as abdominal distension, abdominal pain, as well as cardiac arrest caused by various cardiac arrhythmias, severe vomiting, diarrhea, or renal impairment. It can be treated with medications such as potassium chloride, potassium citrate and potassium glutamate as prescribed by the doctor. It is recommended that patients should follow the doctor’s prescription for medication when low potassium occurs, and should not use drugs indiscriminately on their own.