A 7-Day-Old Infant with Jaundice and Thrombocytopenia.

A3,520-g boy was born at 38 weeks gestation to a 32-yearold G1P1 woman. The mother had a temperature of 101°F at the time of delivery. It was a normal pregnancy, labor, and delivery. The baby was treated with antibiotics because of the mother’s fever. Initial blood count revealed hemoglobin of 18.3 g/dL; white blood cell count of 21,500/mm3 with 43% neutrophils, 4% bands, 4% metamyelocytes, 5% myelocytes, 2% promyelocytes, and 42% lymphocytes; and platelet count of 60,000/mm3. All cultures were negative. The baby and mother were discharged on the fourth day of life. On day of life 7, the baby was noted to be jaundiced by the pediatrician and was found to have a total bilirubin level of 20.5 mg/dL. The baby had been exclusively breast-feeding without difficulty since discharge. He was referred for evaluation. The repeat complete blood count (CBC) was notable for hemoglobin of 16.3 g/dL; white blood cell count of 16,300/mm3 with 45% lymphocytes, 30% neutrophils, 12% bands, 6% metamyelocytes, 5% myelocytes, and 2% promyelocytes; and platelet count of 55,000/mm3. C-reactive protein measurements on both admissions were normal. Family history was unremarkable. On examination, the baby was alert and vigorous. Vital signs were unremarkable. The entire physical examination was normal. Robert Listernick, MD, moderator: Comments? Aaron Hamvas, MD, neonatologist: Obviously, the first thing we would worry about is an infectious process, even with the original negative cultures. The left shift on the CBC is quite striking. However, the Creactive protein levels were normal and the baby looks well. Dr. Listernick: And the persistent thrombocytopenia? Dr. Hamvas: Once infection has been eliminated as a possibility, I would next consider neonatal alloimmune thrombocytopenia (NAIT). There’s nothing in the history or physical examination to suggest a congenital infection. In addition, the baby doesn’t have any limb abnormalities as might be seen in such syndromes as thrombocytopenia with absent radii. Dr. Listernick: Should we be worried about bleeding, such as an intraventricular hemorrhage (IVH)? Dr. Hamvas: This is a nebulous area. Most of the studies, which are mainly retrospective, suggest that the risk of spontaneous IVH increases when the platelet count is below 30,000/mm3. As such, I wouldn’t worry too greatly in this baby. Dr. Listernick: Let’s talk about NAIT. Alexis Thompson, MD, pediatric hematologist: In some ways, NAIT is analogous to Rh-associated hemolytic disease of the newborn except that NAIT frequently occurs in the first pregnancy. Essentially, the mother generates antibodies against a paternal-derived antigen on the baby’s platelets, most commonly the human platelet antigen (HPA)-1a. Dr. Listernick: What is the treatment of NAIT? Dr. Thompson: As has been said, the risk of bleeding at this level of thrombocytopenia is very low. In this case, we didn’t recommend any treatment. With severe thrombocytopenia, we generally use intravenous immunoglobulin. Dr. Listernick: I know I’m pretty old, but as a resident I learned that we should transfuse maternal platelets because they don’t have the offending antigen. Dr. Thompson: That used to be true, but it is extremely cumbersome and may take several days to obtain Robert Listernick, MD, is an Attending Physician, Ann & Robert H. Lurie Children’s Hospital of Chicago; and a Professor of Pediatrics, Northwestern University, Feinberg School of Medicine, Division of Academic General Pediatrics. Address correspondence to Robert Listernick, MD, via email: [email protected].