The normal value of serum potassium in the body is 3.5-5.5 mmol/L. Potassium ion is the main cation in intracellular fluid. Potassium can play a role in maintaining the osmotic pressure of intracellular fluid, participating in the regulation of acid-base balance, maintaining the stress of muscles and nerves as well as the synthesis and metabolism of substances in the cells. The normal range of serum potassium concentration is 3.5-5.5 mmol/L. If it is lower than the normal range, it suggests the presence of low potassium. If it is lower than the normal range, it suggests the presence of hypokalemia, which may be caused by consumptive diseases, long-term low-potassium diet, severe vomiting and diarrhea, etc. If it is higher than the normal range, it suggests the presence of hyperkalemia, which may be caused by acute renal failure, blood transfusion reaction and other diseases. It is recommended to go to the hospital when abnormal serum potassium concentration occurs, so that the doctor can make a judgment and identify the cause of the disease.