title: Recommendations for appropriate activated partial thromboplastin time reagent selection and utilization.
abstract: The activated partial thromboplastin time (aPTT) is widely used as a screening coagulation test and for monitoring unfractionated heparin therapy. Various commercial reagents are available, with different performance characteristics, particularly responsiveness to the lupus anticoagulant (LA). Because aPTT reagent selection significantly affects the interpretation of results, we reviewed College of American Pathologists proficiency testing data involving approximately 4,000 coagulation laboratories, and conducted a survey of coagulation laboratories (n = 93) using The Fritsma Factor hemostasis Web site to determine the basis for aPTT reagent selection. The data demonstrate that for routine aPTT testing, most laboratories use reagents with high/moderate responsiveness to LA. Significant misunderstanding was apparent regarding the use of appropriate aPTT reagent for routine testing and LA identification. We recommend aPTT reagents with low LA responsiveness to screen for coagulation factor deficiencies and heparin monitoring, and suggest continued education of laboratory professionals and reagent manufacturers about appropriate aPTT reagent use.
authors.affiliation: Department of Pathology and Division of Laboratory Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA.
authors.forename: George A
authors.initials: GA
authors.lastname: Fritsma
authors.forename: Francine R
authors.initials: FR
authors.lastname: Dembitzer
authors.forename: Ankush
authors.initials: A
authors.lastname: Randhawa
authors.forename: Marisa B
authors.initials: MB
authors.lastname: Marques
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Van Cott
authors.forename: Dorothy
authors.initials: D
authors.lastname: Adcock-Funk
authors.forename: Ellinor I
authors.initials: EI
authors.lastname: Peerschke
mesh_terms: D000925:Anticoagulants / Q000097:blood*; D001780:Blood Coagulation Tests; D003625:Data Collection; D006493:Heparin / Q000097:blood*; D006801:Humans; D007155:Immunologic Factors / Q000097:blood*; D007202:Indicators and Reagents / Q000145:classification / Q000592:standards; D020407:Internet; D016682:Lupus Coagulation Inhibitor / Q000097:blood*; D010314:Partial Thromboplastin Time / Q000379:methods / Q000592:standards*; D017410:Practice Guidelines as Topic; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D000925:Anticoagulants; D007155:Immunologic Factors; D007202:Indicators and Reagents; D016682:Lupus Coagulation Inhibitor; D006493:Heparin