Q&A column, 11/15
November 2015—Is there a recommended procedure for or reference article about checking APTT reagent sensitivities (for the identification of factors VIII and IX) when changing lot numbers and reference range? The activated partial thromboplastin time (APTT) clot-based assay is a global test used to detect factor deficiencies in patients with a bleeding diathesis or as a preoperative screen to ensure normal coagulation laboratory parameters before an invasive procedure.