High platelets in children can cause the following dangers: First, they can cause blood clots in children. When the platelets are high, the blood viscosity of children increases, which affects the blood circulation of children and can even cause the formation of blood clots. Second, it can cause bleeding in children. This is because after the platelet count is significantly high, it can cause clotting dysfunction, resulting in bleeding. Finally, an increase in platelets in children can also cause hepatosplenomegaly, resulting in symptoms such as weakness and lack of energy, especially in children who are young and show a decrease in activity. Children with high platelets can be treated with drugs such as aspirin or dipyridamole.