LabMed

Factor VII Deficiency – Acquired

At a Glance

Acquired factor VII deficiency may be suspected in a patient who has an increased prothrombin time (PT) with a normal activated partial thromboplastin time (aPTT) and no prior history of congenital factor VII deficiency. Isolated acquired factor VII deficiency is uncommon. However, this problem is typically associated with severe bleeding.

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

Acquired factor VII deficiency must be differentiated from inherited factor VII deficiency and from acquired disorders due to liver disease, vitamin K deficiency and therapy with vitamin K antagonists. The differential is based on patient and family histories, concurrent diseases and therapies. Importantly, laboratory results for thePT and the aPTT should be included with corresponding appropriate specific coagulation factor values. These values include a decreased factor VII coagulant activity (FVII:C) and normal coagulant activities for factors II, IX, and X. (Table 1)

Table 1

Test Results Indicative of the Disorder
Prolonged Prothrombin Time Normal activated Partial Thromboplastin Time
Decreased Factor VII Coagulation Activity Normal Factors VIII, IX, X, XI, XII.

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?

Numerous problems frequently arise because of incorrectly collected or deteriorated specimens. The appropriate ratio of anticoagulant to blood in the testing vessel is also essential. Additionally, the correct anticoagulant solution must be utilized for clinical coagulation times, such as the PT and factor VII coagulant activity. Most testing sites use 3.2% sodium citrate as the anticoagulant of choice. Although other anticoagulants, such as ethylenediaminetetraacetic acid (EDTA) and/or heparin, are used for some laboratory tests, this is not the case for factor VII testing.

What Lab Results Are Absolutely Confirmatory?

In confirming a suspicion of acquired factor VII deficiency, the ordering clinician should ensure a fresh sample has been collected and tested within the allotted time requested by the testing laboratory. After confirming the presence of an intact proper specimen, the FVII:C assay is necessary for evaluating the FVII level to rule in or rule out factor VII deficiency. It should also be verified that the patient does not currently take a medication, such as warfarin, associated with decreased FVII:C.

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

Obtaining a platelet count, as well as liver function tests, can help guide the clinician to additional causes of bleeding not necessarily resulting from acquired FVII deficiency.

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?

Rarely, penicillins and cephalosporins have been associated with selective factor VII deficiency. Second-generation anticoagulants, termed "superwarfarins," as rodenticides can also cause decreased factor VII:C.

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