Challenges and priorities for patients with immune thrombocytopenic purpura and their physicians

Immune thrombocytopenic purpura (ITP) is a disorder of too few platelets (termed thrombocytopenia), the smallest of the circulating blood cells. ITP is defined as isolated thrombocytopenia with no clinically apparent associated conditions or other causes of thrombocytopenia, such as congenital/hereditary thrombocytopenias, drug-induced thrombocytopenia, or autoimmune disorders such as systemic lupus erythematosus [1,2]. “Isolated” thrombocytopenia implies that the red blood cells and white blood cells are normal in number and appearance. The function of blood platelets is to provide initial hemostasis in response to vessel injury, creating a plug to prevent bleeding. Hemostasis is a term to describe prevention of bleeding. If blood vessel injury is small and superficial, the platelet plug is sufficient to stop bleeding. If the vessel injury is extensive, platelets can provide only an initial, temporary seal; permanent hemostasis of larger wounds requires plasma coagulation factors (such as antihemophilic factor and fibrinogen) to provide a strong fibrous matrix to strengthen the platelet plug [3]. Therefore the health problem of patients with ITP, and perhaps their only problem, is a risk for excessive bleeding. The normal platelet concentration in blood is 150,000–350,000 × 10 /L. Like many body functions, the normal number of platelets far exceeds the minimum requirement to provide effective hemostasis. A platelet count of 50,000 × 10 /L is sufficient to stop excessive bleeding following major trauma, surgery, or childbirth. A platelet count of 10,000–20,000× 10/L is sufficient to prevent spontaneous bleeding