title: Patterns of thrombocytosis and thrombocytopenia in hospitalized neonates.
abstract: OBJECTIVE
  We sought to identify changes in platelet (PLT) counts over time, and to evaluate the patterns of thrombocytopenia and thrombocytosis in hospitalized infants 23.8 weeks to term gestation.
  
  
  METHODS
  Neonates were divided into four gestational age groups and their PLT counts were retrospectively compared for prevalence of thrombocytopenia, thrombocytosis, and associated conditions.
  
  
  RESULTS
  Postconceptional age, postnatal age, and sepsis (among other factors) affected PLT counts. When counts from noninfected appropriately grown infants were evaluated, the risk of thrombocytopenia and thrombocytosis were highest in the most preterm infants, and these risks changed with corrected gestational age. PLT counts increased weekly over the first 4 weeks of life for all but the most preterm infants.
  
  
  CONCLUSIONS
  These data characterize the incidence of thrombocytopenia and thrombocytosis across a wide range of gestational ages and show that, even in noninfected neonates, these conditions are common, and risk decreases with increasing maturity. The age-related changes in PLT patterns may reflect maturation of platelet regulation.
authors.affiliation: Department of Pediatrics/Neonatology, University of Washington, Seattle, WA 98195-6320, USA.
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: McPherson
authors.forename: Sandra
authors.initials: S
authors.lastname: Juul
mesh_terms: D006760:Hospitalization; D006801:Humans; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000097:blood*; D007235:Infant, Premature, Diseases / Q000097:blood; D010976:Platelet Count; D013921:Thrombocytopenia / Q000209:etiology*; D013922:Thrombocytosis / Q000209:etiology*