Three-year-old dwarfism can be caused by congenital hypothyroidism, chondrodysplasia, pituitary dwarfism, etc. The performance of different causes is not the same, and it is mainly manifested in short stature, and some of them will have abnormal stature proportion, abnormal intelligence, and skeletal developmental deformities. 1. Congenital hypothyroidism: it manifests as low intelligence, very low IQ, impaired development of facial appearance, and a large tongue that often sticks out of the mouth; impaired development of the femur, tibia and other major long bones, resulting in a body proportion that is shorter in the lower half of the body and longer in the upper half of the body; and delayed sexual development, or in some cases, the sexual development is not affected. 2. Chondrodysplasia: the length of the trunk bone is often normal, but the limbs are obviously short, and the lower half of the body is significantly shorter than the upper half of the body; the spine is forward convex, the abdomen is forward, and the buttocks are pouting, which is very typical; the intelligence is not affected. 3. Pituitary dwarfism: growth retardation, no pubertal initiation period, “old child” premature aging appearance in adulthood; short body, but normal proportion; pubertal hypoplasia of sex organs, secondary sexual characteristics do not develop; normal intelligence. There may be other manifestations of dwarfism at the age of 3, so it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or therapy.