ABSTRACT
CONTEXT.: Automated analyzers have advanced the field of clinical hematology, mandating updated complete blood count (CBC) reference intervals (RIs) to be clinically useful. Contemporary newborn CBC RI publications are mostly retrospective, which some authors have cited as one of their cardinal limitations and recommended future prospective studies. OBJECTIVE.: To prospectively establish accurate hematologic RIs for normal healthy term newborns at 24 hours of life given the limitations of the current medical literature. DESIGN.: This prospective study was conducted at an academic tertiary care center, and hematology samples were collected from 120 participants deemed to be normal healthy term newborns. Distributions were assessed for normality and tested for outliers. Reference intervals were values between the 2.5th percentile and 97.5th percentile. RESULTS.: The novel RIs obtained for this study population are as follows: absolute immature granulocyte count, 80/µL to 1700/µL; immature granulocyte percentage, 0.6% to 6.1%; reticulocyte hemoglobin equivalent, 31.7 to 38.4 pg; immature reticulocyte fraction, 35.9% to 52.8%; immature platelet count, 4.73 × 103/µL to 19.72 × 103/µL; and immature platelet fraction, 1.7% to 9.8%. CONCLUSIONS.: This prospective study has defined hematologic RIs for this newborn population, including new advanced clinical parameters from the Sysmex XN-1000 Automated Hematology Analyzer. These RIs are proposed as the new standard and can serve as a strong foundation for continued research to further explore their value in diagnosing and managing morbidities such as sepsis, anemia, and thrombocytopenia.
