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Bone marrow biopsy was historically performed in any individual with a low platelet count, notes Howard A. Liebman, MD. Today, a blood smear showing normal white and red blood cells in the presence of low platelet counts is considered isolated thrombocytopenia that may be due to secondary causes, such as viral infection or disorders involving antibodies. Liebman comments that bone marrow biopsy should be considered in patients who have other abnormalities identified on their blood smear, such as white cell dysplasia or anemia that cannot be explained by bleeding or iron deficiency.
Acute immune thrombocytopenia was typically thought of as a pediatric disease, while chronic immune thrombocytopenia was considered an adult disease. In the present day, new definitions segregate the early-stage disease into an acute phase and a persistent phase.
Acute phase immune thrombocytopenia persists for 3 months and is self-limiting in the majority of cases. During this 3-month period, explains Liebman, 50% of children will have spontaneous remission. The persistent phase lasts from 3 months to 1 year, and 80% of children (or very young adults) may experience spontaneous remission; the remaining 20% will develop chronic immune thrombocytopenia beyond 1 year from initial diagnosis.
Leibman explains that in the pediatric population, up to two-thirds of the cases are preceded by a history of febrile illness. Pregnancy can create another challenge for differential diagnosis of immune thrombocytopenia. Keith McCrae, MD, states that in incidental thrombocytopenia of pregnancy, platelets drop about 10%, but return to normal levels afterward.