title: Acquired factor V inhibitor associated with life-threatening bleeding and a mixing test result that indicated coagulation factor deficiency.
abstract: A mixing test is useful for distinguishing between coagulation factor deficiency and the presence of inhibitor as the cause of coagulopathy. However, we experienced a patient with acquired factor V (FV) inhibitor whose mixing test showed a coagulation factor deficiency pattern. A 65-year-old man with a tendency for bleeding was referred to our center. The laboratory data showed remarkable prolongation of prothrombin time and activated partial thromboplastin time (APTT). FV activity was less than 3%. A mixing test showed a coagulation factor deficiency pattern. However, neither the tendency for bleeding nor the coagulation tests were corrected by transfusion of fresh frozen plasma. A few days later, a positive test for FV inhibitor of 3 Bethesda units was obtained. Therefore, we started prednisolone and plasma exchange, and the coagulation test results normalized after 6 weeks. Although an incubation period is generally not considered necessary in a mixing test for FV inhibitor, we repeated mixing tests with various incubation periods and confirmed an incubation period-dependent prolongation of the APTT. Therefore, a mixing test with an incubation period is recommended for the detection of FV inhibitor, since a mixing test without an incubation period may show a coagulation factor deficiency pattern when the titer of FV inhibitor is low.
authors.affiliation: Jichi Medical University, Saitama, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ashizawa
authors.forename: Shun-ichi
authors.initials: S
authors.lastname: Kimura
authors.forename: Hidenori
authors.initials: H
authors.lastname: Wada
authors.forename: Kana
authors.initials: K
authors.lastname: Sakamoto
authors.forename: Miki
authors.initials: M
authors.lastname: Sato
authors.forename: Kiriko
authors.initials: K
authors.lastname: Terasako
authors.forename: Misato
authors.initials: M
authors.lastname: Kikuchi
authors.forename: Hideki
authors.initials: H
authors.lastname: Nakasone
authors.forename: Shinya
authors.initials: S
authors.lastname: Okuda
authors.forename: Shinichi
authors.initials: S
authors.lastname: Kako
authors.forename: Rie
authors.initials: R
authors.lastname: Yamazaki
authors.forename: Kumi
authors.initials: K
authors.lastname: Oshima
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Matsuura
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Ohmori
authors.forename: Seiji
authors.initials: S
authors.lastname: Madoiwa
authors.forename: Junji
authors.initials: J
authors.lastname: Nishida
authors.forename: Jun
authors.initials: J
authors.lastname: Mimuro
authors.forename: Kaoru
authors.initials: K
authors.lastname: Tabei
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Sakata
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Kanda
mesh_terms: D000368:Aged; D001777:Blood Coagulation; D019774:Blood Coagulation Factor Inhibitors / Q000097:blood*; D001780:Blood Coagulation Tests / Q000379:methods; D005165:Factor V / Q000037:antagonists & inhibitors*; D006470:Hemorrhage / Q000097:blood*; D006801:Humans; D008297:Male
chemical_list: D019774:Blood Coagulation Factor Inhibitors; C035876:factor V clotting antigen; D005165:Factor V