title: Absolute immature platelet count dynamics in diagnosing and monitoring the clinical course of thrombotic thrombocytopenic purpura.
abstract: BACKGROUND
  Thrombotic thrombocytopenic purpura (TTP) is a life-threatening diagnosis requiring prompt initiation of therapeutic plasma exchange (TPE). Measurement of immature platelet (PLT) fraction (%-IPF) differentiates PLT consumption or destruction from hypoproduction.
  
  
  METHODS
  Our study evaluated %-IPF changes over the course of TTP treated with TPE and as a measure of treatment efficacy. Eleven idiopathic TTP patients, two human immunodeficiency virus (HIV)-associated TTP patients, and five non-TTP patients with thrombocytopenia were enrolled into our study. All patients were treated with TPE and had ADAMTS13 activity measured.
  
  
  RESULTS
  All idiopathic TTP patients had a significantly increased %-IPF and decreased absolute immature PLT count (A-IPC) and PLT count at presentation. An A-IPC value of less than 5 × 10(9) /L at presentation has 84.6% sensitivity, 80% specificity, and 91.7% positive predictive value for diagnosing TTP. A concurrent steady decline in %-IPF and increased PLT counts toward normal was observed in TTP patients undergoing TPE. The A-IPC, however, showed an increase and decrease curve that was not seen in the two HIV-associated TTP patients with no response to TPE and the five non-TTP patients. More importantly, reaching an A-IPC ratio of 3 compared to baseline value during TPE can readily differentiate idiopathic TTP from the other two groups and is correlated with good clinical responses to TPE. An abrupt increase of A-IPC during TPE was also noted in a TTP patient who relapsed 3 days before PLT count decrease. A-IPC is positively correlated with ADAMTS13 activity at presentation but negatively correlated with ADAMTS13 activity during recovery.
  
  
  CONCLUSIONS
  A-IPC should be routinely analyzed for diagnosing and monitoring TTP patients.
authors.affiliation: Department of Pathology, University Hospitals Case Medical Center, Cleveland, Ohio.|Case Western Reserve University School of Medicine, Cleveland, Ohio.
authors.forename: Hong
authors.initials: H
authors.lastname: Hong
authors.affiliation: Department of Pathology, University Hospitals Case Medical Center, Cleveland, Ohio.|Case Western Reserve University School of Medicine, Cleveland, Ohio.
authors.forename: Wenbin
authors.initials: W
authors.lastname: Xiao
authors.affiliation: Department of Pathology, University Hospitals Case Medical Center, Cleveland, Ohio.|Case Western Reserve University School of Medicine, Cleveland, Ohio.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Stempak
authors.affiliation: Department of Pathology, University Hospitals Case Medical Center, Cleveland, Ohio.|Case Western Reserve University School of Medicine, Cleveland, Ohio.
authors.forename: Linda M
authors.initials: LM
authors.lastname: Sandhaus
authors.affiliation: Department of Pathology, University Hospitals Case Medical Center, Cleveland, Ohio.|Case Western Reserve University School of Medicine, Cleveland, Ohio.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Maitta
mesh_terms: D051722:ADAM Proteins / Q000097:blood / Q000172:deficiency; D000071120:ADAMTS13 Protein; D015415:Biomarkers; D001792:Blood Platelets / Q000166:cytology; D016922:Cellular Senescence; D003663:Decision Trees; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D015658:HIV Infections / Q000150:complications; D006801:Humans; D008297:Male; D008875:Middle Aged; D010951:Plasma Exchange; D010976:Platelet Count; D011697:Purpura, Thrombotic Thrombocytopenic / Q000097:blood* / Q000175:diagnosis / Q000209:etiology / Q000628:therapy; D013921:Thrombocytopenia / Q000097:blood / Q000175:diagnosis / Q000628:therapy; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human