title: Platelet function in adult ITP patients can be either increased or decreased, compared to healthy controls, and is associated with bleeding risk.
abstract: OBJECTIVE
  To test whether, together with platelet count, platelet activity could be an important predictor of bleeding risk in immune thrombocytopenia (ITP) patients.
  
  
  METHODS
  Platelet activity was tested by flow cytometric measurement of agonist induced P-selectin expression and compared between 23 adult ITP patients and 22 healthy volunteers.
  
  
  RESULTS
  Platelet activity could be either increased or decreased in ITP patients, compared to healthy volunteers. In the lowest platelet count category, normal to low platelet activity was associated with the biggest increase in bleeding risk. Risk difference 80% (95% confidence interval: 45-115%) for <32 × 10(9) platelets/L. For higher platelet counts, there was no association of platelet activity with bleeding risk.
  
  
  CONCLUSIONS
  Increased platelet activity was associated with decreased bleeding risk, but only in patients with low platelet counts.
  
  
  CONCLUSIONS
  Platelet activity can be a predictor of bleeding risk in ITP patients with low platelet counts.
authors.affiliation: a Sanquin Research , Center for Clinical Transfusion Research , Leiden , The Netherlands.|b Department of Clinical Epidemiology , Leiden University Medical Center , Leiden , The Netherlands.
authors.forename: Rutger A
authors.initials: RA
authors.lastname: Middelburg
authors.affiliation: a Sanquin Research , Center for Clinical Transfusion Research , Leiden , The Netherlands.
authors.forename: Jannemieke C
authors.initials: JC
authors.lastname: Carbaat-Ham
authors.affiliation: a Sanquin Research , Center for Clinical Transfusion Research , Leiden , The Netherlands.
authors.forename: Husna
authors.initials: H
authors.lastname: Hesam
authors.affiliation: a Sanquin Research , Center for Clinical Transfusion Research , Leiden , The Netherlands.
authors.forename: Max A A D
authors.initials: MA
authors.lastname: Ragusi
authors.affiliation: a Sanquin Research , Center for Clinical Transfusion Research , Leiden , The Netherlands.|c Department of Immunohematology and blood transfusion , Leiden University Medical Center , Leiden , The Netherlands.
authors.forename: Jaap Jan
authors.initials: JJ
authors.lastname: Zwaginga
mesh_terms: D001792:Blood Platelets / Q000378:metabolism*; D016022:Case-Control Studies; D005260:Female; D006470:Hemorrhage / Q000097:blood; D006801:Humans; D008297:Male; D010976:Platelet Count; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000097:blood*; D012307:Risk Factors
keywords: Bleeding; Immune thrombocytopenia (ITP); Platelet function; Platelets