title: Determination of the rate of reduction in platelet counts in recipients of hematopoietic stem and progenitor cell transplant: clinical implications for platelet transfusion therapy.
abstract: BACKGROUND
  To investigate how a delay between pretransfusion platelet count measurement and actual platelet transfusion affects the assessment of platelet transfusion responses, the rate of reduction in platelet counts was determined in 30 patients with relatively uncomplicated thrombocytopenia.
  
  
  METHODS
  Fifteen adult and 15 pediatric patients admitted for hematopoietic stem and progenitor cell transplantation were studied. Platelet counts before and after myeloablative conditioning and after prophylactic platelet transfusions were determined and studied as a function of time. The rates of reduction in platelet counts were determined by linear regression analysis.
  
  
  RESULTS
  Platelet counts were reduced at linear rates after myeloablative conditioning or prophylactic platelet transfusion in all 30 patients. The average rates of reduction in platelet counts after myeloablation were 1261 +/- 583 and 1070 +/- 492 platelets per microL per hour (mean +/- SD) for adult and pediatric patients, respectively. The average rate of reduction after platelet transfusions during the thrombocytopenic phase was 740 +/- 280 and 820 +/- 288 platelets per microL per hour (mean +/- SD) for adult and pediatric patients, respectively. The rates of reduction in platelet counts between the two phases were significantly different in the two age groups (adult, p < 0.0001; pediatric, p < 0.015) and were proportionally correlated with initial platelet counts immediately before myeloablation and after prophylactic platelet transfusions.
  
  
  CONCLUSIONS
  The rate of reduction in platelet count can have a significant impact on the evaluation of platelet transfusion responses when there is a delay between pretransfusion measurement of platelet count and the initiation of platelet transfusion. In addition, the rate of platelet reduction determined from this study can be used to confirm an accelerated rate of platelet consumption in thrombocytopenic patients.
authors.affiliation: Department of Pathology, University of Florida Health Science Center, Gainesville, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: del Rosario
authors.forename: K I
authors.initials: KI
authors.lastname: Kao
mesh_terms: D000293:Adolescent; D000328:Adult; D001792:Blood Platelets / Q000166:cytology / Q000378:metabolism*; D001804:Blood Transfusion, Autologous; D002648:Child; D002675:Child, Preschool; D005260:Female; D018380:Hematopoietic Stem Cell Transplantation; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D017713:Platelet Transfusion; D012044:Regression Analysis; D013921:Thrombocytopenia / Q000628:therapy; D013997:Time Factors; D019172:Transplantation Conditioning