Symptoms of calcium deficiency in 13-year-old children are mainly increased neuromuscular excitability, restlessness, tremor, startled jumping, hand and foot twitching, convulsions, and poor bone calcification. Generally speaking, the recommended daily intake of calcium for 13 year olds is around 1200mg/day, which can usually be obtained from food, so there is no need to worry about calcium deficiency in children. If calcium deficiency occurs, it can lead to increased nerve excitability, tremor, jumping, and even low calcium convulsions, and long-term chronic calcium deficiency can lead to osteocalcinosis. If the above symptoms occur, can be supplemented by diet, such as eating more calcium-containing foods, such as milk, cheese, soybeans and other foods for supplementation, if necessary, can be prescribed by the doctor to calcium gluconate for supplementation. If your child develops symptoms, consult a doctor for dietary guidance and, if necessary, medication.