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Overestimation of Baseline Factor IX Activity in a Patient with Mild Hemophilia B by Soy Phosphatide-Containing aPTT Reagent in a One-Stage Assay
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  • Michael Losos,
  • Janine Martin,
  • Paul Steele,
  • Cristina Tarango,
  • Lori Luchtman-Jones
Michael Losos
Cincinnati Children's Hospital Medical Center
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Janine Martin
Cincinnati Children's Hospital Medical Center
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Paul Steele
Cincinnati Children's Hospital Medical Center
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Cristina Tarango
Cincinnati Children's Hospital Medical Center
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Lori Luchtman-Jones
Cincinnati Children's Hospital Medical Center
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Abstract

Testing and screening for factor deficiency using one-stage clotting assays is the most prevalent methodology, but it is susceptible to misestimating a patient’s true coagulable state due to either the clot detection methodology or the aPTT reagents involved. In our case report, a 16-year-old with mild hemophilia B had a normal aPTT and factor IX activity using a new platform in the clinical laboratory. We evaluated the impact of instrument and aPTT reagents that differed in clot detection methodology, the activator and the source of phospholipid in one stage assays (OSA) for FIX:C and aPTT using plasma from this patient.