Factor VII Deficiency
Factor VII deficiency can be easily diagnosed when a coagulation screening work-up reveals an isolated prolonged prothrombin time (PT) with a normal activated partial thromboplastin time (aPTT). The assay for the other vitamin K-dependent clotting factors is not necessary but is useful for ruling out the rare inherited combined deficiencies of vitamin K-dependent factors; in this case, however, the aPTT is also prolonged.31
Distinguishing congenital FVII deficiency from acquired FVII deficiency is also straightforward. Individuals with acquired FVII deficiency previously had normal FVII levels and PT but may acquire FVII deficits as a result of excessive consumption and/or insufficient production of FVII. In such cases, FVII deficiency would be associated with deficiencies in the other coagulation factors, which (like FVII) are vitamin K-dependent and produced in the liver. In cases of acquired FVII deficiency related to severe infections, the FVII deficit may be isolated and transient. In very rare cases, acquired FVII deficiency may be related to the development of autoantibodies directed against FVII.24
Differentiating congenital FVII deficiency from other congenital bleeding disorders cannot be performed on the basis of bleeding history, especially in women and when the disorder is characterized mainly by mucocutaneous hemorrhages.