I [Geo] am preparing an audio PowerPoint module describing the primary coagulation assays, PT, PTT, TT, and fibrinogen [Fg] assays. I asked several colleagues if we continue to encounter factor V inhibitors. Before ~2010 we encountered anti-FV and sometimes anti-FV plus anti-FII [prothrombin] as cross-reacting antibodies that arose in response to bovine thrombin used in a surgical sealing material sometimes called “fibrin glue.” We agreed that all the fibrin glue products now available employ human thrombin, either plasma-derived or synthetic and that we are no longer encountering these inhibitors.
I did find, however, a series of three case studies documenting one congenital factor V deficiency treated with platelet concentrate and two factor V inhibitors that formed subsequent to piperacillin- tazobactam or ciprofloxacin exposure, attached. I’m curious to learn if any of our participants have recently found patients with factor V inhibitors.
We have a current patient
We have a current patient with factor V inhibitor, ~80 YOA male , who has been ticking along for about 18 months now, no history of fibrin glue or other cause attributed. Factor V level ranges 0.03 to 0.10 U/mL and Bethesda about 2-3 BU/mL from the initial level of 43 at diagnosis. Regards Robyn.
Dear George,
Dear George,
Following your post, I can tell you that we presented a poster for the last virtual ISTH 2021 meeting. It was a case report where we described a FV inhibitor found in a patient with Strongyloides stercoralis infestation and antibiotic therapy in the Hospital Dr. Cesar Milstein in Argentina. The abstract can be found at: Res Pract Thromb Haemost 2020, Vol 4 Issue S1 page 337. Regards, Mirta Arias.
We saw a spate of FV
We saw a spate of FV inhibitors [and published these] in the early 2000’s [Favaloro EJ, et al. Factor V inhibitors: rare or not so uncommon? A multilaboratory investigation. Blood Coagulation & Fibrinolysis, 2004; 15: 637–47]. But since use of bovine thrombin was ceased soon thereafter, cannot recall many thereafter. But sure, can still arise in congenital factor V deficiency [NB: platelets are a rich source of factor V] or after some antibiotics.