title: Determination of reference ranges for immature platelet and reticulocyte fractions and reticulocyte hemoglobin equivalent.
abstract: BACKGROUND
  The immature platelet and immature reticulocyte fractions represent the ratios of platelets and reticulocytes recently released into the circulation and thus with higher RNA content. They are considered early indicators of bone marrow recovery.
  
  
  OBJECTIVE
  The aim of this study was to determine the reference ranges for the immature platelet and reticulocyte fractions of hematologically normal individuals in a university hospital.
  
  
  METHODS
  Venous blood samples collected in ethylenediaminetetraacetic acid K3 were analyzed using a Sysmex XE-5000™ analyzer. Individuals with platelet and reticulocyte counts within the reference ranges, and a blood count within the laboratory's screening criteria were included. Individuals with clinical conditions that could affect hematological results were excluded. The immature platelet fraction, high, medium and low fluorescence reticulocyte fractions and reticulocyte hemoglobin equivalent were evaluated. The reference ranges were determined according to the recommendations of the International Federation of Clinical Chemistry.
  
  
  RESULTS
  One hundred and thirty-two outpatients were evaluated. The mean age was 44 years (range: 13-80 years), 72 (54.5%) were women treated in a university hospital. The mean platelet count was 250.8×109/L and the mean reticulocyte count was 0.052×109/L. The following reference ranges were obtained: immature reticulocyte fraction 1.6-12.1%, the high, medium and low fluorescence reticulocyte fractions were 0.0-1.7%, 1.6-11.0% and 87.9-98.4%, respectively, the reticulocyte hemoglobin equivalent was 30.0-37.6% and immature platelet fraction was 0.8-5.6%. There was a statistically significant difference (p-value=0.006) between genders in respect to the immature platelet fraction with 0.8-4.7% for females and 0.7-6.1% for males. The immature reticulocyte fraction was directly correlated with the reticulocyte count.
  
  
  CONCLUSIONS
  Determining the reference range is critical to the introduction of a new parameter. The reference ranges obtained herein corroborate those reported in previous publications and will contribute to the clinical and laboratory application of the indices.
authors.affiliation: Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, RS, Brazil. Electronic address: iurimorkis2@gmail.com.
authors.forename: Iuri Vicente Camargo
authors.initials: IV
authors.lastname: Morkis
authors.affiliation: Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, RS, Brazil.
authors.forename: Mariela Granero
authors.initials: MG
authors.lastname: Farias
authors.affiliation: Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, RS, Brazil.
authors.forename: Luciana
authors.initials: L
authors.lastname: Scotti
keywords: Immature platelet fraction; Immature reticulocyte fraction; Reference interval