title: Percentage of hyperdense cells: Automated parameter to hereditary spherocytosis screening.
abstract: BACKGROUND
  The hereditary spherocytosis (HS) is a common cause of inherited hemolytic anemia that is difficult to identify in many cases. Currently, there are new economic parameters for red cell disorder evaluation, such as hyperdense cell percentage (%Hyper) obtained from automated analyzers.
  
  
  OBJECTIVE
  In this study we determined the %Hyper efficacy and compared its accuracy with a flow cytometry method in HS, hemoglobinopathy and healthy individuals, in order to allow the use of %Hyper in HS screening.
  
  
  METHODS
  Patients treated at the outpatient clinic at the Hospital de Clínicas de Porto Alegre (HCPA) were allocated into three groups according to their clinical condition: HS, hemoglobinopathy or healthy groups. Flow-cytometric osmotic fragility test (FCM OF) method was used as reference to compare with %Hyper, both performed from K2EDTA samples.
  
  
  RESULTS
  Fifty-eight individuals were included in this study. We found that the %Hyper cut-off point of 6.4% showed an excellent sensitivity (92.3%) and specificity (90.7%) to detect HS. Besides, %Hyper presented a significant negative correlation with FCM OF in identifying HS (Rs=-0.525; P<0.001).
  
  
  CONCLUSIONS
  %Hyper could be a tool for screening HS, before requesting additional tests. It is a fast and cost-effective test, which is easily obtained in complete blood count, favoring its use in clinical laboratories. However, this test does not replace flow cytometric methods for confirmation of atypical cases.
authors.affiliation: Unit of Hematology, Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil. Electronic address: mgfarias@hcpa.edu.br.
authors.forename: Mariela Granero
authors.initials: MG
authors.lastname: Farias
authors.affiliation: Unit of Hematology, Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil. Electronic address: pfreitas@hcpa.edu.br.
authors.forename: Priscila Aparecida Correa
authors.initials: PA
authors.lastname: Freitas
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D057205:Automation, Laboratory / Q000295:instrumentation / Q000706:statistics & numerical data; D001772:Blood Cell Count; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D004912:Erythrocytes / Q000473:pathology*; D005260:Female; D005434:Flow Cytometry / Q000706:statistics & numerical data*; D006453:Hemoglobinopathies / Q000175:diagnosis* / Q000473:pathology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009996:Osmotic Fragility; D010045:Outpatients; D012680:Sensitivity and Specificity; D013103:Spherocytosis, Hereditary / Q000175:diagnosis* / Q000473:pathology
keywords: Flow cytometry; Hereditary spherocytosis; Hyperdense cells