If you suspect that a child is deficient in trace elements, you can check the following ways: 1. You can check the trace elements in the peripheral blood. After collecting the peripheral blood from the child, you can test the concentration of trace elements in the blood, such as the concentration of iron, calcium and zinc, and if there are obvious abnormalities, you need to treat the child accordingly. If there is a zinc deficiency, the child should be given oral zinc gluconate supplements in a timely manner, otherwise, zinc deficiency in children may cause anorexia and other symptoms. However, checking peripheral blood can cause unstable test results and is not recommended.2. The trace element content of hair can be checked, but this method is also unstable and is not recommended.3. The concentration of trace elements in venous blood can be checked for children, which is the most accurate and appropriate way. Blood can be collected from the jugular vein or elbow vein of the child to detect trace elements, and the treatment can be carried out accordingly according to the concentration of trace elements, which is the most recommended method.