Demonstrability of thrombopoietic serum activity in patients with disturbed thrombocytopoiesis

Serum thrombocytopoietic activity was measured by radioisotope bioassay in several groups of patients with disturbed thrombocytopoiesis. More or less serum activity was demonstrated in nearly all groups of patients with thrombocytopenia or elevated platelet count. The test system used proved to be more sensitive than counting circulating platelets.