Secondary Thrombocytosis in Children

Secondary thrombocytosis is defined as a growth of platelet number over 440.000/mm3 or more than 2 standard deviations, secondary to a primary disease like iron deficiency anemia or an infection. It is frequently observed in children, especially in infants and young children, often randomly discovered. There are few data published on the incidence and the significance of secondary thrombocytosis. Many causes are known, but two major processes are involved: increased medullar production or abnormal control from spleen. It is believed to be a benign condition. The study of platelet dynamics could provide information about the course of the primary disease.