A patient with an acquired deficiency of Factor V may have a bleeding disorder.
Laboratory features:
(1) prolonged PT and PTT
(2) normal thrombin time (unless DIC present)
(3) decreased Factor V activity and/or antigen
Types of deficiency:
(1) quantitative deficiency due to decreased production and/or consumption
(2) inhibitor-related
Causes of a quantitative deficiency in Factor V:
(1) severe liver disease
(2) DIC
Inhibitors may occur:
(1) in patients with hereditary deficiency of Factor V
(2) due to Factor V antibodies, which may arise spontaneously or as a result of exposure to bovine Factor V (in topical bovine thrombin)
Type of Acquired Defect
Effect of In Vivo Addition of Normal Plasma
Factor V deficiency
PT and PTT corrected
Factor V inhibitor
PT and PTT remain prolonged)
Replacement of Factor V does not work in a patient with an inhibitor. A patient with an inhibitor may respond to immunosuppressive therapy (corticosteroids, cytotoxic agents) or intravenous gamma globulin.
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