Neonatal Alloimmune Thrombocytopenia - NAIT

Neonatal alloimmune thrombocytopenia (NAIT), also referred to as fetal and neonatal alloimmune thrombocytopenia or perinatal alloimmune thrombocytopenia, is the most common cause of thrombocytopenia in an otherwise healthy newborn.  NAIT is caused by alloantibodies formed by the mother in response to a paternally inherited human platelet antigen (HPA) that is on the surface of fetal platelets; these maternal alloantibodies pass through the placenta to the fetus, causing fetal platelet destruction.  Many cases of NAIT are mild, resulting in only skin manifestations. Left untreated, mild cases may resolve within 2 weeks of birth.   NAIT can also cause severe thrombocytopenia (platelet count <50,000/µL), resulting in intracranial hemorrhage (ICH) and even infant death, although severe hemorrhages are uncommon.   Laboratory testing is used to diagnose NAIT in an affected infant and to determine the risk of NAIT in future pregnancies.  Testing involves evaluation of maternal serum for platelet alloantibodies and genotyping or phenotyping of the maternal, paternal, and/or the neonatal platelets.    NAIT can occur in first pregnancies. After diagnosis, subsequent pregnancies should be monitored and antenatal therapy can be used to avoid bleeding complications. 

Tabs Content
Content Review: 
April 2019

Last Update: April 2019