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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