Platelet kinetic studies were performed in eight patients with paroxysmal nocturnal hemoglobinuria (PNH) but without symptoms or signs related to thrombosis. Indium-111 tropolonate labeled autologous platelets were used to determine mean platelet life and platelet production rate; total body images were also acquired. Three of seven patients with a thrombocytopenia showed a shortened mean platelet life, and the other five demonstrated a (nearly) normal platelet survival. Four of the seven patients with thrombocytopenia showed a decreased platelet production rate, but bone marrow cellularity was normo- to hypercellular. These observations suggest ineffective thrombopoiesis in 57% of the patients with PNH and thrombocytopenia. Total body imaging was performed during the platelet kinetic study in order to study organ uptake. Imaging of the abdominal vessels was demonstrated in all patients, suggesting enhanced adherence of platelets to the endothelium in patients with PNH. Since thrombosis of especially the abdominal vessels is a major cause of morbidity and mortality, the use of antithrombotic drugs might be considered despite the absence of abdominal complaints.
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