The causes of low potassium include insufficient intake, excessive excretion, and transfer of extracellular potassium into the cells. 1. Inadequate intake: prolonged fasting without adequate potassium supplementation during intravenous nutrition or prolonged malnutrition can lead to low potassium. 2. Excessive discharge: Severe diarrhea, vomiting, etc. can lead to loss of potassium via gastrointestinal tract; long-term or excessive use of potassium-excreting diuretics can lead to potassium discharge via kidney; large amount of sweating in high temperature environment can lead to potassium discharge via skin, when potassium is discharged excessively, it can lead to hypokalemia. 3. Transfer of extracellular potassium to intracellular: Certain drugs (e.g. insulin, salbutamol and terbutaline) can cause potassium to enter the cells from the bloodstream, leading to hypokalemia. Low potassium can lead to muscle weakness and cardiac arrhythmia, etc. Prompt medical attention and standardized potassium supplementation are required.