NEONATAL THROMBOCYTOPENIA - INCIDENCE, SEROLOGICAL AND CLINICAL OBSERVATIONS

In this study, platelet counts were determined from the cord blood of consecutive 9142 newborns. Neonates with known autoimmune thrombocytop enia were not included. The platelet count <100 x 10(9)/L was found in 64 newborns. In five of them, neonatal alloimmune thrombocytopenia (N AIT) was diagnosed. The overall incidence of neonatal thrombocytopenia was 0.7% the incidence of NAIT was about 10 times less. Serological a nd clinical observations are summarized from 238 thrombocytopenic newb orns (54 from the above group and 184 previously referred to serologic al investigations). All of the newborns were divided into two groups: NAIT (46 cases) and other thrombocytopenias (192 cases). Among platele t-specific antibodies in NAIT 91.4% were anti-HPA-1 a, the rest were a nti-HPA-1 b and anti-HPA-5b. In the majority of the cases, antibodies were detectable by the platelet suspension immunofluorescence test (PS IFT) and monoclonal antibody immobilization of platelet antigens (MAIP A) assay. In 19.6% cases, antibodies were detectable by MAIPA only. In 70.9% of these cases, antibodies were undetectable. Thrombocytopenia <50 x 10(9)/L and hemorrhagic diathesis were more often observed in NA IT than in other thromboctopenias, whereas associated disorders that c ould contribute to thrombocytopenia, here observed almost only in the latter group. We also report certain other observations, such as the p resence of anti-HLA antibodies, a rise in the anti-HPA-1 a antibody ti ter after infection without pregnancy, and a higher incidence of petec hiae in nonimmune thrombocytopenia as compared with the incidence of l ow platelet counts.