A high platelet count, also known as thrombocytosis, means there are too many platelets or thrombocytes, which are cells that help blood to clot. An elevated platelet count is not unusual in young children. Normal platelet numbers range between 150,000 to 450,000 in a microliter of blood. Testing the platelet count in your blood helps to diagnose disorders of the blood and bone marrow.
Up to 13 per cent of children have thrombocytosis, according to "Thrombocytosis in Childhood" by E. Mantadakis. An increase in platelets does not always indicate disease. If it is benign, it may be a temporary result of medications, blood loss or surgery. Infection is the most common cause of elevation in children. A sample of venous blood is taken, diluted and the platelets are counted -- something usually done by passing the sample through an electronic counter. Automated counting is often associated with falsely elevated platelet counts.
An elevated platelet count can be a sign of serious conditions such as kidney disease, some anaemias, connective tissue diseases, inflammatory bowel disease, liver tumours, leukaemia or polycythemia vera, which is a disorder that causes the bone marrow to produce too many platelets. A complete patient history and physical examination are necessary, and a range of other tests may be necessary to rule out such conditions. Platelet levels may require regular monitoring.
Primary and Secondary Thrombocytosis
Most cases of thrombocytosis in children are secondary, which means that an increase in platelets occurs as the result of another condition, benign or not. Primary or essential thrombocytosis that develops on its own is rare. It has an incidence of about one in 1 million children. It follows a variable course and is not well understood. This condition raises platelet numbers to levels above 600,000 per microliter and the spleen becomes enlarged.
Most childhood thrombocytosis is usually self-limiting and does not usually require any treatment. However, if repeated blood testing shows a prolonged, unexplained elevation of platelet numbers and misshapen or abnormal platelets, a physician should investigate. There may be bleeding problems like failure of blood to clot. Essential thrombocytosis can be a fatal condition. The platelet count can reach levels of over 2 million per microliter.