At a Glance

Patients with severe deficiency (<1% factor) develop symptoms within the first 6 years of life and present with umbilical stump bleeding, easy bruising and epistaxis.

Acquired factor V deficiency causes, such as disseminated intravascular coagulation (DIC) and liver disease, must be excluded.

What Tests Should I Request to Confirm My Clinical Dx? In addition, what follow-up tests might be useful?

The diagnosis of factor V deficiency is made by demonstrating a prolonged prothrombin time (PT), prolonged partial thromboplastin time (PTT), normal thrombin time, correction of the 1:1 mixing study for the PT and PTT and an isolated decrease in factor V activity level. There is a normal level for fibrinogen and factors II, V, VII, VIII and X.


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Fibrinogen, D-dimer or fibrin split products might be useful to exclude DIC (low fibrinogen activity and high fibrin split products/D-dimer).

What Lab Results Are Absolutely Confirmatory?

An isolated decrease in factor V activity level is confirmatory. Factor V levels are typically in the range of 0-17%.

What Tests Should I Request to Confirm My Clinical Dx? In addition, what follow-up tests might be useful?

Factor V is a glycoprotein found in plasma and alpha granules of platelets. Platelet factor V accounts for about 20% of the total factor V level. A syndrome of combined congenital deficiencies of factors V and VIII exist and must be distinguished from simple factor V deficiency.

Spontaneous inhibitors of factor V in patients without factor V deficiency have been reported postoperatively in association with the use of antibiotics, such as aminoglycosides and penicillin, and with the use of bovine thrombin or fibrin.