A normal platelet count ranges from 150,000 to 450,000 platelets per microliter of blood. Having more than 450,000 platelets is a condition called thrombocytosis.
Thus, using 150–400×109/L as the normal range for platelet count, a number of thrombocytopenia in children and that of thrombocytosis in adult males could.
It affects both children and adults. If for any reason your blood platelet count falls below normal, the condition is called thrombocytopenia.