Reference Intervals in Neonatal Hematology

"Normal ranges" for hematologic values of neonates are not available. This is because blood is not drawn on healthy normal neonates to establish such ranges, as is done with the consent of healthy adult volunteers. Instead, neonatal hematology utilizes "reference intervals." These consist of 5th to 95th percentile values compiled from laboratory tests that were performed on neonates thought to have minimal pathology relevant to the specific laboratory test under consideration, or with pathology unlikely to significantly affect that test result. The premise on which the reference interval concept is based is that these values approximate normal ranges, although they were admittedly obtained for a clinical reason and not from healthy volunteers. Basically, reference intervals are the best tools we have to interpret a neonate's complete blood count (CBC), and they likely will continue to be the best we will have for several years to come [1].