title: Examination of the percentage of immature platelet fraction in term and preterm infants at birth.
abstract: BACKGROUND
  Reticulated platelets (RPs) are newly synthesized platelets. Recently, an automatic method was established to detect RPs as a percentage of the immature platelet fraction (IPF%). Although, neonates often develop thrombocytopenia at some time during their hospitalization, the details of IPF% in neonates remain unclear. We, therefore, studied the relations between IPF% and other factors to gain a more detailed understanding of IPF% in neonates.
  
  
  METHODS
  The following clinical data were obtained from the medical records of 105 neonates who met our inclusion criteria: Gestational age, birth weight, IPF% and platelet count of neonatal peripheral blood at birth, and perinatal data. The subjects were divided into three groups: Group A, birth weight standard deviation score (SDS) ≥ -2 standard deviation (SD) and ≤ +2 SD; Group S, < -2 SD; and Group L, > +2 SD.
  
  
  RESULTS
  IPF% correlated negatively with platelet count at birth in the whole study population. IPF% was 2.8 ± 1.3% in term neonates, and IPF correlated negatively with gestational age and birth weight. Platelet count correlated positively with birth weight SDS in the whole study population and in Group S. IPF% correlated negatively with birth weight SDS in the whole study population and in Group S. In neonates with a platelet count below 25 × 10(4)/μl, IPF% correlated negatively with platelet count. Among other neonates, however, IPF% remained almost constant.
  
  
  CONCLUSIONS
  Monitoring of IPF% is useful for estimating the function of thrombocytopoiesis in neonates and preterm infants.
authors.affiliation: Department of Neonatology, Japanese Red Cross Medical Center, Shibuya-Ku, Tokyo, Japan.
authors.forename: Sakurai
authors.initials: S
authors.lastname: Yuko
authors.affiliation: Department of Neonatology, Japanese Red Cross Medical Center, Shibuya-Ku, Tokyo, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Takeda
authors.affiliation: Department of Neonatology, Japanese Red Cross Medical Center, Shibuya-Ku, Tokyo, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hirota
authors.affiliation: Department of Neonatology, Japanese Red Cross Medical Center, Shibuya-Ku, Tokyo, Japan.
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Hisaeda
authors.affiliation: Department of Neonatology, Japanese Red Cross Medical Center, Shibuya-Ku, Tokyo, Japan.
authors.forename: Syusuke
authors.initials: S
authors.lastname: Amakata
authors.affiliation: Department of Neonatology, Japanese Red Cross Medical Center, Shibuya-Ku, Tokyo, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nakao
authors.affiliation: Department of Neonatology, Japanese Red Cross Medical Center, Shibuya-Ku, Tokyo, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kawakami
keywords: Birth weight standard deviation score; XE-2100; immature platelet fraction; small for gestational age infant; thrombocytopenia