The normal value of serum calcium is 2.25-2.75 mmol/L. There are two forms of calcium present, ionized calcium and bound calcium, and a dynamic balance is maintained between them. ionized calcium plays an important role in the regulation of physiological functions in the body, and the level of blood calcium is affected by the acidity and alkalinity of the body. Blood calcium levels increase when acidosis occurs and decrease when alkalosis occurs. At the same time, calcium ions have the role of reducing neuromuscular stress, such as low blood calcium, neuromuscular excitability will increase, it is easy to occur hand and foot twitch, the people are called cramps, especially in the elderly more common some. When the blood calcium increases, the neuromuscular excitability will be reduced, and the patient will show weakness, indifferent expression, weakened tendon reflexes, and in serious cases, mental disorders, such as coma, etc. In addition, other serious conditions such as cardiac arrest can easily occur when blood calcium is too high. Therefore, maintaining blood calcium at normal levels is very important for the maintenance of normal physiological functions of the body.