Intact megakaryocytes in the venous blood as a marker for thrombopoiesis.

A total of 110 children, aged 0-15 years, were investigated for circulating megakaryocytes in cubital venous blood using the saponin-haemolysis leucoconcentration technique. The average number of megakaryocytes decreased from 17.8 per ml blood in the first year of life to 5.5 after the 6th year, which is the same value as in adult humans. The intact thrombocytogenic megakaryocyte value decreases from about 40% in the first year of life to only a few percent (less than 5%) after the 10th year, the same value as in adult humans. There was a significantly higher number of megakaryocytes in children aged 0-6 years than in those aged 7-15 years. We concluded that occurrence of intact megakaryocytes greater than or equal to 25% in the venous blood is a sign of a normal thrombopoietic activity in the bone marrow, and the percentage of intact megakaryocytes in cubital venous blood reflects the decrease in thrombopoiesis in the bone marrow of fingers, hands and forearms during childhood. The decline in thrombopoietic activity is concentrated in three periods: 1-3, 6-7, and 10-11 years. An occurrence of intact megakaryocytes greater than 5% in venous blood draining organs or bone marrow is a sign of some thrombopoietic activity.