Mild calcium deficiency usually does not have twitching symptoms; if severe calcium deficiency occurs, hypocalcemia will occur, which is common in hypoparathyroidism and severe vitamin D deficiency. Mild hypocalcemia is characterized by abnormal sensation around the fingers, toes and mouth and lips, numbness and tingling sensation in the limbs, and twitching sensation in the hands and feet. The occurrence of hypocalcemia is dangerous, but there is no need to be overly afraid, seek medical attention as soon as possible. Calcium gluconate injection can quickly replenish the blood calcium to the normal range, and the symptoms are significantly relieved. It is important to further investigate the cause of low blood calcium, such as parathyroid hormone, vitamin D, etc.