Complete blood count parameters for healthy, small-for-gestational-age, full-term newborns E. O ¨ ZYU ¨ REK*, S. C ¸ ETINTAS ¸ †, T. CEYLAN‡, E. O ¨ G ˘ U ¨ S ¸ §, A. HABERAL¶, B. GU ¨ RAKAN**, N. O ¨ ZBEK* *Hematology Section, Department of Pediatrics, Bas ¸ kent University Faculty of Medicine, Ankara, Turkey  Department of Pediatrics, Bas ¸ kent University Faculty of Medicine, Ankara, Turkey àBiochemistry Laboratory, Bas ¸ kent University Faculty of Medicine, Ankara, Turkey §Department of Biostatistics, Bas ¸ kent University Faculty of Medicine, Ankara, Turkey –Department of Obstetrics and Gynecology, Bas ¸ kent University Faculty of Medicine, Ankara, Turkey **Neonatology Section, Department of Pediatrics, Bas ¸ kent University Faculty of Medicine, Ankara, Turkey Summary No previous study has investigated the full range of complete blood count (CBC) parameters in small-for-gestational-age (SGA) newborns. The main aim of this study was to compare CBC and peripheral smear parameters in term, healthy SGA neonates and appropriate-for- gestational-age (AGA) neonates, and to establish CBC reference values for full-term SGA newborns. One hundred thirty-two healthy, term newborns (73 SGA and 59 AGA) were included. On day 1, we obtained 109 samples and on day 7 we obtained 77 samples. A CBC and peripheral smear were analyzed for each sample collected and group data were com- pared. We observed higher mean values for normoblast count, hemoglobin, hematocrit, and red blood cell (RBC) count in the SGA babies than in the AGA babies on day 1. The mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration values for the SGA babies were decreased because of the relatively high RBC count and relatively high mean corpuscular volume we observed in this group. Of the SGA newborns, 21.9% had neutropenia and 4.7% had absolute neutrophil counts lower than 1500/ll on day 1. On both day 1 and day 7, the SGA newborns had higher mean absolute metamyelocyte counts and higher mean I : T (immature : total neutrophil ratio) values than the AGA group. The SGA babies had a lower mean absolute lymphocyte count on day 7 than the AGA group. We detected thrombocytopenia in almost one-third of the 64 SGA newborns tested on day 1. In summary, our study clearly demonstrates that CBC parameters for healthy, full- term, SGA newborns are different from those of healthy, term AGA newborns. This is the first study that has documented different mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, metamyelocyte counts, lym- phocyte counts, and I : T in SGA babies compared with AGA babies. Keywords Term AGA newborn, term SGA newborn, venous complete blood count, peripheral smear Introduction Complete blood count (CBC) results for newborns must be interpreted according to data recorded for the baby’s gestational age group. If this is not done, results may be misinterpreted and diagnosis of conditions such as infec- tion may be missed or delayed. Results for certain CBC parameters in newborns with intrauterine growth retar- dation differ from those in full-term, appropriate-for- gestational-age (AGA) newborns. Small-for-gestational-age (SGA) neonates have clinical problems linked to intrauterine hypoxia and decreased subcutaneous fat tissue. Some of the common issues in these newborns include hypoxic-ischemic encephalopathy; Received 19 August 2005; accepted for publication 10 January 2006 Correspondence: NamıkO ¨ zbek, Hematology Section, Department of Pediatrics, Bas ¸ kent University Faculty of Medicine, 6. Cadde, No.: 72/ 3, Bahc ¸elievler, 06550 Ankara, Turkey. Tel.: +90 312 2130776; Fax: +90 312 2157597; E-mail: nozbek@tr.net Clin. Lab. Haem. 2006, 28, 97–104 Ó 2006 Blackwell Publishing Ltd 97