LabMed

Factor V Deficiency – Acquired

At a Glance

Acquired factor V deficiency can occur in a number of situations. One possibility is the presence of a specific inhibitor to factor V. This can occur in a patient with factor V deficiency following treatment with products containing factor V, such as fresh frozen plasma, either prophylactically, or to treat a bleeding episode.

Factor V deficiency can also be acquired in patients who have been treated with "fibrin glue." This is a mixture of human cryoprecipitate with bovine thrombin (factor IIa). The bovine preparation of thrombin is often contaminated with bovine factor V. A small percentage of patients who are treated with fibrin glue can develop antibodies to bovine factor V, which cross-react with human factor V, producing a factor V deficiency. Factor V can be decreased along with several of the other coagulation factors in patients with severe liver disease. Factor V can also be consumed in active clotting. Therefore, patients in disseminated intravascular coagulation (DIC) who are tested while factor consumption is active can show decreased levels of factor V.

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

A prolonged prothrombin time (PT) and a prolonged partial thromboplastin time (PTT) are consistent with the presence of factor V deficiency. Subsequently, a reduced factor V level must be demonstrated to confirm a diagnosis of a deficiency for this coagulation factor. Patients with acquired factor V deficiency on the basis of an inhibitor to factor V can be identified when the patient's plasma is mixed with normal plasma and the factor V assay is performed.

If there is a neutralizing antibody present in the patient's plasma, the antibody inhibits factor V activity from the normal plasma and the factor V level is decreased in the mixture of plasma. This mixing study is a modification of the classic PT or PTT mixing study, except the factor V level is measured instead of the PT or PTT. This is especially useful in evaluating patients who have developed antibodies to factor V after exposure to bovine thrombin. A patient with a factor V deficiency who is treated with a blood product containing factor V could develop an antibody to factor V, which further reduces the amount of circulating factor V. These patients would have both a congenital deficiency and a circulating antibody to factor V, which further decreases the factor V concentration in the plasma.

In patients with acquired factor V deficiency in whom there is no neutralizing antibody to factor V, such as those with severe liver disease or those in DIC, the factor V level is low along with several other factors. The mixing study in these cases does not reveal the presence of a factor V inhibitor. Acquired factor V deficiency can be differentiated from a simple congenital factor V deficiency in a number of ways. Congenital factor V deficiency patients may have bleeding or bruising from early childhood, depending on the severity of the deficiency, whereas patients with acquired factor V deficiency do not typically show a lifelong history of bleeding. Another clue for an acquired factor V deficiency is the presence of a known cause for the factor V deficiency. As noted, these include exposure to fibrin glue, liver disease and DIC.

Are There Any Factors That Might Affect the Lab Results? In particular, does your patient take any medications - OTC drugs or Herbals - that might affect the lab results?

There are several well-known causes for acquired factor V deficiency. The assay for factor V and the assay for the factor V mixing study do not have significant interferences.

What Lab Results Are Absolutely Confirmatory?

The presence of a low factor V level not present from birth or a low factor V level in a factor V deficient patient that has been further decreased following exposure to blood components with factor V are both indicative of a factor V deficiency that is not purely congenital.

Are There Any Factors That Might Affect the Lab Results? In particular, does your patient take any medications - OTC drugs or Herbals - that might affect the lab results?

An indication that an inhibitor to factor V has arisen is a poor hemostatic response to infusion of a product containing factor V, especially if the product was previously effective in controlling a bleeding episode.

Loading links....

Sign Up for Free e-newsletters

Regimen and Drug Listings

GET FULL LISTINGS OF TREATMENT Regimens and Drug INFORMATION

Bone Cancer Regimens Drugs
Brain Cancer Regimens Drugs
Breast Cancer Regimens Drugs
Endocrine Cancer Regimens Drugs
Gastrointestinal Cancer Regimens Drugs
Genitourinary Cancer Regimens Drugs
Gynecologic Cancer Regimens Drugs
Head and Neck Cancer Regimens Drugs
Hematologic Cancer Regimens Drugs
Lung Cancer Regimens Drugs
Other Cancers Regimens
Rare Cancers Regimens
Skin Cancer Regimens Drugs