More about Fibrinogen Effect on PT and PTT

Please refer to our January 22, 2018 discussion entitled Effect of Fibrinogen on PT and PTT, and especially to the recent comment from “Anders.” Please help Anders and our parcipants find authority for the comment, “In both the PT/INR and PTT pathways, fibrinogen is seldom the limiting factor. The functional fibrinogen level must be below 100 mg/dL to prolong either assay’s clotting time.” George suggests that PT and PTT reagent manufacturers establish fibrinogen sensitivity through the careful preperation of activators and phospholipids, but can find no documentation to support this “expert opinion.”