Immune Thrombocytopenic Purpura



Immune Thrombocytopenic Purpura

Introduction

Most of the time, a run-of-the-mill skinned knee or scraped elbow is nothing to worry about. But for some children, these can be dangerous because their blood doesn't clot properly. In children with ITP, this occurs because the number of platelets, the part of their blood that helps control bleeding, is too low. Immune thrombocytopenic purpura (ITP), sometimes called idiopathic thrombocytopenic purpura, is an autoimmune disorder that occurs when the body destroys its platelets too quickly. Many children with ITP get better on their own over days, weeks or sometimes months. In other cases, medications may be required in order to alleviate the symptoms of ITP.

Normal pregnancy is associated with a physiologic fall in the platelet count that is characterized by a leftward shift in the platelet count distribution. The reason for this decline is unknown, although it has been speculated that these changes may reflect dilution, decreased platelet production, or increased platelet turnover during pregnancy.3 Regardless, the fall in the platelet count during normal pregnancy results in some pregnant women developing platelet counts that fall into the thrombocytopenic range.2 Generally, these individuals have mild thrombocytopenia that first becomes apparent in the mid-second to third trimester of pregnancy. Although there is no well-established minimum value for the platelet count in gestational thrombocytopenia, most experts consider this diagnosis to be less likely when the platelet count falls below 70,000/µL. However, reports exist of more severe thrombocytopenia in pregnant women that was not responsive to steroid therapy and resolved postpartum, and thus was consistent with gestational thrombocytopenia.

Thrombocytopenia

Thrombocytopenia maybe defined as a subnormal number of platelets in the circulating blood. It is the most common cause of abnormal bleeding. In general, the severity and frequency of hemorrhagic manifestations correlate to the platelet count. Platelet counts below 20×109/L usually are associated with spontaneous hemorrhage.

Thrombocytopenia results from three processes: (1) deficient platelet production. Those that depopulate the stem cell or megakaryocyte compartments are the most common, e.g., marrow injury by myelosuppressive drugs or irradiation and aplastic anemia.(2) accelerated platelet destrucion, utilizaton or loss, e.g., idiopathic thrombocytopenia purpura, diffuse intravascular coagulaton, thrombotic thrombocytopenia purpura. (3) abnormal distribution or pooling of the platelets within the body. This type of thrombocytopenia is seen in the various disorders associated with splenomegaly (Bussel, 2007).

Immune Thrombocytopenia

ITP is an uncommon cause of thrombocytopenia in pregnancy, occurring in between 1 in 1000 and 1 in 10,000 pregnant women.6 As opposed to secondary ITP, which develops in association with viral infection (human immunodeficiency virus [HIV], hepatitis C, and Helicobacter pylori), autoimmune disease, and other challenges, factors that induce primary ITP and why its course worsens in some pregnant patients are not well understood. Of all cases of pregnancy-associated ITP, approximately one-third is first diagnosed during pregnancy, whereas two-thirds are in patients with preexisting disease. The clinical features of ITP in a pregnant patient are similar to those encountered in nonpregnant women, with bruising, mucosal bleeding, and petechiae as presenting symptoms whose severity parallel the degree of ...