Journal of Perinatology (2010) 30, 540–545 r 2010 Nature America, Inc. All rights reserved. 0743-8346/10 www.nature.com/jp ORIGINAL ARTICLE Reference ranges for blood concentrations of eosinophils and monocytes during the neonatal period defined from over 63 000 records in a multihospital health-care system RD Christensen1,2, J Jensen1,3, A Maheshwari4 and E Henry1,3 1Intermountain Healthcare Women and Newborns Clinical Program, Ogden, UT, USA; 2McKay-Dee Hospital Center, Ogden, UT, USA; 3Institute for Healthcare Delivery Research, Salt Lake City, UT, USA and 4Divisions of Neonatology and Pediatric Gastroenterology, Departments of Pediatrics, Cell Biology, and Pathology, University of Alabama at Birmingham, Birmingham, AL, USA Introduction Objective: Blood concentrations of eosinophils and monocytes are part Normal values for hematological parameters are not generally of the complete blood count. Reference ranges for these concentrations during available for neonates because blood is not drawn on healthy the neonatal period, established by very large sample sizes and modern neonates to establish normal ranges. Instead, ‘reference ranges’ are methods, are needed for identifying abnormally low or high values. used in neonatal hematology.1–6 These consist of the 5th to 95th Study Design: We constructed reference ranges for eosinophils per ml percentile values assembled from large numbers of neonates with and monocytes per ml among neonates of 22 to 42 weeks of gestation, minimal pathology or with pathology not thought to be relevant to on the day of birth, and also during 28 days after birth. Data were the laboratory parameter under study. Recent examples of their obtained from archived electronic records over an eight and one-half-year usefulness include the following: Reference ranges for erythrocyte period in a multihospital health-care system. In keeping with the indices3 have enabled identifying neonates with hereditary reference range concept, values were excluded from neonates with a spherocytosis on the basis of an elevated mean corpuscular diagnosis of infection or necrotizing enterocolitis (NEC). hemoglobin concentration.7 Reference ranges for platelet Result: Eosinophils and monocytes per ml of blood were electronically concentrations4 have enabled a definition of neonatal retrieved from 96 162 records, of which 63 371 that lacked a diagnosis of thrombocytosis,5 and defining altitude-appropriate reference ranges infection or NEC were included in this reference range report. The mean for blood neutrophil concentrations6 has enabled more precise value for eosinophils per ml on the day of birth increased linearly between 22 identification of neonates with neutrophilia.8 and 42 weeks of gestation, as did the 5 and 95% values. The reference range Abnormal blood concentrations of eosinophils or monocytes at 40 weeks was 140 to 1300 ml–1 (mean 550 ml–1). Similarly, the mean can assist in identifying adults with various pathological value for monocytes increased linearly over this interval, with a reference conditions.9,10 Reference ranges from very large data sets are rangeat40weeksof300to3300ml–1 (mean 1400 ml–1). Over the first 4 lacking for blood concentrations of eosinophils and monocytes weeks after birth, no appreciable change was observed in 5% limit and mean during the neonatal period, particularly among the extremely eosinophil count, with a slight increase in the 95% limit in week 4. A slight low birth weight neonates who now populate most of the level III increase in monocyte count was observed during the first 2 weeks after birth. neonatal intensive care units. Therefore, we constructed reference Conclusion: The results of this analysis describe reference ranges ranges for eosinophils and monocytes of neonates from 22 to 42 for blood concentrations of eosinophils and monocytes during the weeks of gestation on the day of birth, and over the first 28 days neonatal period. Additional study is needed for determining the relevance after birth, using the databases of an 18-hospital system in the of values falling outside the reference range. western United States. Journal of Perinatology (2010) 30, 540–545; doi:10.1038/jp.2009.196; published online 7 January 2010 Methods Keywords: reference range; neonate; eosinophil; monocyte; CBC Information was collected as a de-identified limited data set from archived Intermountain Healthcare records. The information Correspondence: Dr RD Christensen, Department of Neonatology, Intermountain Healthcare, collected was limited to that shown in the figures of this report. 4403 Harrison Boulevard, Ogden, UT 84403, USA. Blood concentrations of eosinophils and monocytes were abstracted E-mail: [email protected] Received 20 August 2009; revised 6 October 2009; accepted 10 November 2009; published online electronically from complete blood counts (CBCs) obtained on 7 January 2010 neonates with a date of birth from 1 January 2002 through 31 May Reference ranges for eosinophils and monocytes RD Christensen et al 541 2009. Values were excluded if a diagnosis was identified anywhere NEC was listed in one or more data-marts, and therefore in the electronic record of infection (bacterial, viral, fungal or these samples were not included in the reference range. protozoal) or necrotizing enterocolitis (NEC). The data fields used Thus, the number of CBC on which the reference range was to identify infection or NEC were International Classification of constructed was 63 371. The exact number of patients at Disease-Ninth Revision, Case Mix (the billing, coding and financial each gestational age contributing data to the reference range is data mart used by Intermountain Healthcare) and EVOX (the shown in Figure 1. extended Vermont-Oxford database). Blood samples were run on a The mean values for eosinophils increased approximately Beckman Coulter LH750 (Fullerton, CA, USA), which is the linearly between 22 and 42 weeks of gestation, as did the 5 and instrument present in all Intermountain Healthcare Hospitals that 95% values. The reference range for eosinophils at 40 weeks of have a level III neonatal intensive care unit.11 Gestational age was gestation was 140 to 1300 ml–1 (mean 550 ml–1; Figure 2). determined by obstetrical assignment unless this was changed by Similarly, the mean values for monocytes increased approximately the neonatal examination. linearly over this interval with a reference range at 40 weeks of 300 The program used for data collection was a modified subsystem to 3300 ml–1 (mean 1400 ml–1; Figure 3). of ‘clinical workstation’. Clinical workstation is a web-based Over the first 4 weeks after birth, no appreciable change was electronic medical record application that stores demographic and observed in 5% limit and mean eosinophil count, with a slight clinical information, such as history, physical examination results, increase in the 95% limit to approximately 1550 ml–1 by week 4 laboratory data, problem lists and discharge summaries. The 3M (Figure 4). A slight increase in mean monocyte count occurred Company (Minneapolis, MN, USA) approved the structure and over the first 2 weeks (Figure 5). definitions of all data points for use within the program. The data were collected from the electronic medical record, laboratory systems and case mix. Data were managed and accessed by authorized data Discussion analysts. Descriptive statistics were calculated using Statit (Corvallis, OR, USA). Means, 5 and 95% confidence intervals were used to Eosinophils are effector cells involved in allergic and nonallergic express the data. The Intermountain Healthcare institutional review inflammatory conditions. Circulating eosinophils are derived from board approved the study as a de-identified, data only investigation myelocytic progenitors within both the marrow and extramedullary not requiring written consent of the individuals. sites. After exiting the site of production and entering the blood, eosinophils circulate for approximately 1 day or so (T1/2 18 h) after which they transmigrate to tissues, primarily in the gastrointestinal tract, in which they produce cytokines and chemokines.10,12 The Results physiological function of eosinophils is still somewhat enigmatic, The absolute numbers of eosinophils and monocytes (cells ml–1 but clearly they are part of a network of cells involved in asthma, blood) were electronically retrieved from 96 162 CBCs obtained allergy, helminthiases and inflammation. from neonates with gestational ages at birth ranging from 22 to 42 Monocytes are part of the reticuloendothelial system, which is weeks; 32 971 of these were from patients in which infection or composed of granulocytic precursors, circulating monocytes and 16000 14000 12000 10000 8000 6000 Number of Records 4000 2000 0 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 Gestational Age (weeks) Figure 1 The number of records at each gestational age, from 22 to 42 weeks, represented in the subsequent studies. Journal of Perinatology Reference ranges for eosinophils and monocytes RD Christensen et al 542 2000 1800 1600 1400 1200 1000 800 Eosinophils y = 0.3461x2- 2.9231x + 80.083 600 400 200 0 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 Gestational Age Figure 2 Reference range for blood concentration of eosinophils (eosinophils per ml of blood) on the day of birth, shown according to gestational age. The lower and upper lines represent the 5 and 95% limits and the middle line represents the mean value. 3500 3000 2500 2000 y = 1.6517x2- 67.372x + 1402.2 1500 Monocytes 1000 500 0 22 23 24 25