RETICULATED PLATELET VALUES IN NORMAL AND THROMBOCYTOPENIC NEONATES

Objectives: Reticulated platelets (RPs) are newly synthesized platelet s with increased ribonucleic acid content. The percentage of RPs is el evated in adults with thrombocytopenia as a result of increased platel et 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 me asured at birth in 89 neonates without thrombocytopenia in three gesta tional age groups (<30, 30 to 36, and >36 weeks), six neonates with im mune thrombocytopenia, and one neonate with thrombocytopenia as a resu lt of decreased platelet production. Results: The RP percentages in ne onates without thrombocytopenia >36 weeks and 30 to 36 weeks of gestat ion 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 less than or equal to 0.0001). Term neona tes with immune thrombocytopenia had significantly higher RP percentag es (38.3% +/- 23.1%) than term neonates without thrombocytopenia (p = 0.0001), with no overlap in RP values, A lower RP percentage (1.5%) an d significantly lower absolute RP count were measured in the one neona te with decreased platelet production. Conclusions: These preliminary data establish normal RP percentages in term and preterm neonates at b irth and demonstrate elevated RP percentages in neonates with immune p latelet destruction, The RP values may be helpful in evaluating the ca uses of neonatal thrombocytopenia.