Micronutrient testing is only a screening tool, and the test results can only be used as a reference value to determine whether a baby is deficient in micronutrients. First of all, the Ministry of Health of China has clearly stipulated that micronutrient testing should not be given to babies under 6 months of age as far as possible. This is because the trace elements obtained and stored in the baby’s body can meet the baby’s growth needs until 5-6 months after birth. Second, be sure to communicate with your doctor about your baby’s overall feeding before checking trace elements. If the doctor determines that the child’s nutrition is well structured and the diet is balanced, then there is no need to check the trace elements. If the child is not fed properly and has some clinical symptoms, only then may the trace elements be checked, and only through blood tests that have some reference significance, but not through other means. At present, there is no accurate and unified standard for trace element testing internationally. Some people take a device in the community and say that they can test for iron and zinc deficiency without drawing blood, but this device can be adjusted at will and is not credible. There are also ways to use hair or other tissues to test, which is also unscientific. The use of hair to measure trace elements has now been eliminated in the United States. Because the hair is different and the growth rate can be different, and because the amount of trace elements is already very small, it is difficult to accurately reflect the true level of trace elements in the body through hair testing. Iron deficiency can be easily detected by blood sampling, but for other trace elements such as zinc and copper, because the amount in the body is very small, there is no good reference standard, and the test results may not be very objective.