Reticulated platelet values in normal and thrombocytopenic neonates.

OBJECTIVES: Reticulated platelets (RPs) are newly synthesized platelets with increased ribonucleic acid content. The percentage of RPs is elevated in adults with thrombocytopenia as a result of increased platelet destruction. The objectives of this study were to determine normal RP values in neonates at birth and to determine whether neonates with thrombocytopenia as a result of increased platelet destruction have an increased percentage of RPs. STUDY DESIGN: The RP percentages were measured at birth in 89 neonates without thrombocytopenia in three gestational age groups (<30,30 to 36, and >36 weeks), six neonates with immune thrombocytopenia, and one neonate with thrombocytopenia as a result of decreased platelet production. RESULTS: The RP percentages in neonates without thrombocytopenia >36 weeks and 30 to 36 weeks of gestation were 4.0% +/- 2.4% (mean +/- SD) and 4.6% +/- 1.7%, respectively, similar to values reported in healthy adults. Neonates younger than 30 weeks of gestation had significantly higher RP percentages (8.8% +/- 5.1%) than older neonates (p