Platelets are cells in the blood that are called “platelets” because of their slightly concave, oval or disc-shaped shape. Platelets are formed by shedding fragments of cytoplasm from bone marrow megakaryocytes. Platelet count refers to the number of platelets per unit volume of blood. In normal people, the number of platelets in the blood is maintained at a certain level, and certain disease causes can lead to a decrease or increase in the number of platelets. The normal value of platelets in babies is 100-300×10^9/L. If the platelets are high, it is generally a reactive platelet increase, which is common in some acute and chronic inflammation, iron deficiency anemia, etc. After treatment, the number of platelets will quickly return to normal level. In addition, iron deficiency anemia can cause small red blood cell size, and these small red blood cells are treated as platelets when counting, resulting in a false increase in platelets, while iron deficiency anemia can cause secondary thrombocytosis, which can return to normal when the anemia is cured. After the child grows to a certain stage, he must add supplementary food in time, otherwise it will trigger iron deficiency anemia, normally, after 8 months of age, the child can eat some eggs, vegetable puree and other foods, if the child has partial food, you need to help the baby correct in time. Primary thrombocytosis is common in myeloproliferative disorders, chronic granulocytic leukemia, true erythrocytosis, and primary thrombocytosis, and these conditions require identification of the cause and treatment.