There are two ways to test for trace elements: one is to test for trace elements in hair; the other is to test for trace elements in blood. Most hospitals use the blood trace element test, which does not require fasting and does not require intravenous blood collection, but only fingertip blood collection. Trace elements usually include calcium, iron, zinc, magnesium, etc. Zinc deficiency can affect the child’s taste development and neurological development. When calcium is low, it can affect the health of bones. When iron is deficient, it can easily lead to iron deficiency anemia and insufficient hemoglobin synthesis, so it is important to pay some attention to the testing of trace elements.