Neonatal Isoimmune Thrombocytopenia: The Natural Course and Management and the Detection of Maternal Antibody

Isoimmune neonatal thrombocytopenia purpura (INTP) is a disease caused by platelet destruction by maternally derived antibody. Six patients were investigated. Maternal derived platelet trans fusions in two patients resulted in posttransfusion platelet counts of greater than 85,000/μl, a normal platelet survival of 7 to 10 days, and an early discharge from the hospital. In four patients, random donor platelet transfusions administered in the first week caused a transient rise of between 7 and 30,000 platelets per μl with a return to pretransfusion levels 24 to 48 hours later, confirming the ineffectiveness of this form of treatment. Corticosteroid therapy is not effective and because of its potential toxicity should not be recommended for use in INTP. Platelet antigen was identified in the parents, and maternal sensitization was proven by the presence of platelet specific antibody. Severity of the disorder was estimated by the initial platelet count and the duration in weeks for the platelet count to rise above 100,000/μl. Lymphocytotoxicity and immune lysis, as measured by the 51Chromium release assay, did not show an obvious relationship with the severity of the disorder. In our patients, high scores in the platelet suspension immunofluo rescence test related to a more severe disorder, but a larger series would be necessary to confirm this finding.