High platelet count in children may be caused by primary thrombocythemia or anemia, and may also be caused by inflammation and infection. 1. Primary thrombocythemia: some children with high platelets are usually associated with congenital hereditary diseases, such as primary thrombocythemia, which is a myeloproliferative disease caused by gene mutation, and will have high platelet values; 2. anemia: if children have anemia, it may also lead to elevated platelets, mainly because of the decline in hemoglobin, caused by compensatory bone marrow proliferation; 3. Inflammatory infections: if the child’s body has inflammatory infections, it will make the number of white blood cells increase, resulting in compensatory bone marrow proliferation, so it will lead to increased platelet values. Children with high platelets are advised to go to a regular hospital for relevant examinations to clarify the specific causes, and actively follow the doctor’s instructions to adopt suitable solutions to avoid delaying the condition.