Based on clinical experience, trace element test reports include calcium (although not a trace element), iron and zinc, which are of great concern to parents. Nutrient deficiencies cannot be diagnosed by lab tests alone, but must be based on the infant’s feeding, growth and development, and symptoms, combined with the lab results. Parents need to know that calcium data is not clinically meaningful. Ninety-nine percent of the body’s calcium is stored in the bones and only one percent is in the blood, intracellular and extracellular spaces. The normalcy of calcium levels in the blood is regulated by its own endocrine regulation to keep blood calcium within normal limits, because normal blood calcium does not mean that the child is not calcium deficient. Because of this, infants grow rapidly, growing 15 cm in the first year, requiring large amounts of calcium. Dairy products are natural calcium supplements, and if infants eat more than 600 ml of dairy products, their calcium needs will be sufficient. However, the absorption and utilization of calcium depends on the action of vitamin D. The amount of vitamin D in mother’s milk is very little, and a daily supplement of 400 international units of vitamin D is needed to ensure the absorption and utilization of calcium. Parents should never assume that because the blood calcium is normal, the child does not need calcium. There are many babies born at full term under 6 months with low blood zinc, but the baby is breastfed and is growing well in height and weight. As mentioned earlier, this is generally not a zinc deficiency because, the lab results are for reference only and no zinc supplementation is needed. It is also not necessary to check the serum iron. The presence of anemia can be determined by checking the hemoglobin, which is generally diagnosed below 110 g/l. The most accurate test for iron deficiency before anemia is serum ferritin, but this test cannot be done in a general laboratory, so it is usually not needed. Some mothers often ask: “Does my baby still need iron supplementation after adding iron-containing rice flour?” The answer is: you still need to take iron supplements because the amount of iron in rice flour is very small, and your baby should not take too much rice flour at one time. In addition, some babies may have gastrointestinal reactions to iron supplements, so you can start with a small amount and gradually adapt. Iron is very important for baby can only develop, so it must be taken consistently.