Secondary thrombocytosis

    Secondary thrombocytosis, or reactive thrombocytosis, occurs as a result of a physiologic reaction to a primary event. Primary thrombocytosis in pediatric patients is very rare, while reactive thrombocytosis is very common. It is associated with a diversity of clinical conditions, such as infection or malignant disease. Infections of the central nervous system are the most common cause of an elevated platelet count in children. In addition, several studies have shown that pediatric patients with lower respiratory tract infections often present with thrombocytosis. In these cases, platelet count can be used as a valuable clinical marker to assess the severity of the infection. Malignant diseases are scarcely associated with extreme cases of thrombocytosis.
     The degree of reactive thrombocytosis is related to the child’s age, and increase in platelet count is proportional to hospitalization duration. The degree of thrombocytosis is negatively related to hemoglobin value and positively related to white cell count.
      Usually when the patient is treated and the condition that is stimulating thrombocytosis has ceased, platelet count returns to normal level. Even though the platelet count is highly elevated, complications associated with it are very rare. Physicians should concentrate on the underlying cause of reactive thrombocytosis.