title: Reticulated platelets as a screening test to identify thrombocytopenia aetiology.
abstract: BACKGROUND
  Thrombocytopenia is a common haematological abnormality and no simple diagnostic test is available to diagnose thrombocytopenia pathogenesis.
  
  
  OBJECTIVE
  To evaluate sensitivity and specificity of reticulated platelets (RP) as a diagnostic test for thrombocytopenia with increased thrombopoietic activity.
  
  
  METHODS
  Prospective observational study in thrombocytopenic patients.
  
  
  METHODS
  A direct, whole-blood, dual-labelling flow cytometric method was used. Direct, whole-blood double coverage was achieved using a monoclonal anti-glycoprotein (GP)-III antibody (CD61 PerCP) for platelet identification and thiazole orange (Retic-count) as platelet mARN stain.
  
  
  RESULTS
  RP were measured in 101 thrombocytopenic patients and 104 non-thrombocytopenic controls. The mean RP percentage in 60 thrombocytopenic patients with no increased thrombopoietic activity was 7.5% (CI for 95%: 5.2-9.7) and RP absolute number was 3.2 x 10(9)/l (CI for 95%: 2.1-4.3). The mean RP percentage in 41 thrombocytopenic patients with increased thrombopoietic activity was 30.3% (CI for 95%: 25.1-35.5) and RP absolute number was 6.2 (CI for 95%: 4.8-7.7). The RP percentage cut-off for a diagnosis of thrombocytopenia with increased thrombopoietic activity was 11% [sensitivity 93%, specificity 85%, positive predictive value (PPV) 83%, negative predictive value (NPV) 95%].
  
  
  CONCLUSIONS
  RP measurement by flow cytometry, directly from whole-blood, is a useful screening test to differentiate between thrombocytopenia with high or low thrombopoietic activity. A RP percentage in excess of 11%, has a high sensitivity and good specificity for a diagnosis of thrombocytopenia with increased thrombopoietic activity.
authors.affiliation: Internal Medicine Department, Hospital de Sabadell, Parc Taulí S/N, 08208 Sabadell, Barcelona, Spain. MMonteagudo@tauli.cat
authors.forename: M
authors.initials: M
authors.lastname: Monteagudo
authors.forename: Ma J
authors.initials: MJ
authors.lastname: Amengual
authors.forename: L
authors.initials: L
authors.lastname: Muñoz
authors.forename: J A
authors.initials: JA
authors.lastname: Soler
authors.forename: I
authors.initials: I
authors.lastname: Roig
authors.forename: C
authors.initials: C
authors.lastname: Tolosa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D052160:Benzothiazoles; D001792:Blood Platelets / Q000166:cytology / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D005456:Fluorescent Dyes; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D011446:Prospective Studies; D011804:Quinolines; D013921:Thrombocytopenia / Q000097:blood / Q000209:etiology*
chemical_list: D052160:Benzothiazoles; D005456:Fluorescent Dyes; D011804:Quinolines; C051000:thiazole orange