Thrombocytopenia responding to red blood cell transfusion

Three patients with severe symptomatic iron deficiency anemia and thrombocytopenia had a significant rise in platelet count a few days following packed red blood cell transfusion. Pre-transfusion platelet count of patient one was 17 x 10(9)/L, 22 x 10(9)/L in patient 2 and 29 x 10(9)/L in patient 3. On the 6th day post transfusion, the platelet count rose to 166 x 10(9)/L in patient one, 830 x 10(9)/L in patient 2 and 136 x 10(9)/L in patient 3. The possible mechanisms behind such an unreported observation are discussed.