Factor V Leiden Deficiency

Polycythemia rubra vera: An unlikely cause of severe pulmonary embolism

An 80-year-old female presented with mild pain in the left leg followed a month later by slight shortness of breath without chest pain. The patient had a known history of polycythemia rubra vera (PRV) for at least 3 years, hypertension, and coronary artery disease. She had been followed by a hematologist and was having occasional phlebotomies as needed. On presentation, vital signs were stable including an arterial oxygen saturation of 96%. All laboratory values were unremarkable with the exception of elevated levels of hemoglobin at 19.8 g/dL (normal range: 12-15 g/dL), hematocrit at 69.7% (normal range: 36-48%), and total RBC mass at 38 mL/kg (normal range in females: 21-27 mL/kg). WBC count was slightly high at 14.3×10 mutation was tested and the result was positive. 


A full workup for hypercoagulable tendency (by the patient's hematologist) was unremarkable for all of the following: factor V Leiden (R506Q) mutation, factor II (prothrombin), protein C and S, antithrombin III, lupus anticoagulant, and anticardiolipin. CT of the chest with contrast was ordered. The scan showed a filling defect (arrows, right and left panels) representing pulmonary embolism with thrombus shown in the distal right main pulmonary artery. Mild splenomegaly was noted on examination and CT findings. Left leg deep venous thrombosis (DVT) was diagnosed, followed a month later by right arm DVT and a pulmonary embolism with thrombus in the distal right main pulmonary artery.


Polycythemia rubra vera is a rare myeloproliferative disorder that can be associated with severe organ damage and high mortality ( Figure 1 ). It occurs in about 2 of every 100,000 people. The average age at which PRV is diagnosed is 60 years, and the disorder rarely occurs in people younger than 20 years. More men than women develop PRV. Symptoms and signs usually include headache, breathlessness, disturbed vision, weakness, dizziness, general itching, flushing, facial redness, red eyes, and enlarged spleen or liver. Occasionally, patients with PRV have no symptoms.


Diagnosis Until recently, diagnostic criteria for polycythemia rubra vera were based on the Polycythemia Vera Study Group Diagnostic Criteria, which relied on RBC mass, arterial oxygen saturation, splenomegaly, thrombocytosis, leukocytosis, leukocyte alkaline phosphatase activity, and vitamin B PRV is diagnosed when both major and one minor criterion are present or when the first major criterion is present with any two minor criteria.

Is it Factor V Leiden, or Factor V Deficiency

? The reason I ask is that when I donate blood and tell them I am FV Leiden positive they “call” to see if I can donate, since only FV deficiency is in their book. They have told me to always say I am FV deficient so they do not have to call because the blood center will discard plasma for both disorders.

I just had a problem with that because I was taught that there is a difference: no FV Vs a change in the gene code for FV which causes the FV to work overtime. Thanks.

Hi, Tiffany, it is nice to hear from you. I realize that I’ve met you through the Carolinas Clinical Connection and that you are my neighbor over there in South Carolina.

You are absolutely right, and your blood center should know the difference. We laboratory scientists shoot ourselves in the foot by the way we name our assays. Every day someone gets confused about factor V deficiency and factor V Leiden. Often labs receive specimens accompanied by an isolated order for factor V. We always call, because it would be quite unusual to only test for factor V, we are sure they meant factor V Leiden mutation, and that is what they confirm on the phone.

The letter C gets us into even more trouble: protein C deficiency, activated protein C resistance, and C-reactive protein . Many perfectly intelligent people think this means the letter X, not the Roman numeral X (10). It makes sense.