Generally speaking, it is necessary to measure the vitamin D level in children, especially for children within two weeks of age, because children within two years of age often suffer from vitamin D deficiency rickets, because children within two years of age tend to grow and develop faster, and failure to take vitamin D supplements in a timely manner can cause a decline in intestinal calcium absorption, which can lead to vitamin D deficiency rickets. After the occurrence of vitamin D deficiency rickets, children will often have occipital baldness, chicken chest, rib beads and even X-leg, O-leg, etc. This will have a greater impact on the quality of life and health of children, so it is very necessary to measure vitamin D for children, and when vitamin D deficiency is detected, vitamin D must be supplemented in a timely manner.