Factor V Deficiency: Presentation, Laboratory Findings, and Treatment
Clinical Presentation
Factor V deficiency presents with a heterogeneous bleeding phenotype ranging from mucosal bleeding and easy bruising to severe hemorrhages, though the severity is generally milder than hemophilia A or B. 1, 2
Common Bleeding Manifestations
- Mucosal bleeding (epistaxis, menorrhagia, gingival bleeding) is the most frequently reported symptom 2
- Postoperative hemorrhage and delayed bleeding after trauma or surgery 1
- Easy bruising and ecchymosis 3
- Hemarthroses, intramuscular hemorrhages, and intracranial bleeding can occur but are less common 2
- Bleeding severity correlates poorly with factor V activity levels—patients with similar factor V levels may have vastly different bleeding phenotypes 2
Important Clinical Caveat
Some patients with severe deficiency (factor V activity <1%) may have only mild bleeding symptoms, as demonstrated in documented cases of homozygous mutations 4
Laboratory Diagnosis
Begin with PT and aPTT screening tests; both will be prolonged in factor V deficiency because factor V participates in the common coagulation pathway. 5
Diagnostic Algorithm
Initial Screening Panel 5
- Prothrombin time (PT) - prolonged
- Activated partial thromboplastin time (aPTT) - prolonged
- Complete blood count (to rule out thrombocytopenia)
- Fibrinogen level
Mixing Study (50:50 with Normal Plasma) 5
- Correction of prolonged PT/aPTT indicates true factor deficiency (not an inhibitor)
- Failure to correct suggests presence of an inhibitor 5
Confirmatory Quantitative Testing 5
Severity Classification 5
| Severity | Factor V Activity Level |
|---|---|
| Severe | <10% (or <10 IU/dL) |
| Moderate | 10-30% (10-30 IU/dL) |
| Mild | 30-50% (30-50 IU/dL) |
Critical Distinction
Factor V deficiency (bleeding disorder) is completely unrelated to Factor V Leiden (thrombophilic mutation causing APC resistance)—do not confuse these entities 5. Factor V Leiden requires APC-resistance assays or DNA genotyping 6, 5.
Treatment Options
For bleeding patients with factor V deficiency, platelet transfusions should be the initial therapy, as factor V stored in platelet alpha-granules has greater procoagulant potential than plasma-derived factor V. 3
Acute Bleeding Management
First-Line Therapy
- Platelet transfusions (5 units over 48 hours for significant bleeding) 3
- Factor V in platelet alpha-granules is released locally at sites of vascular injury
- Superior procoagulant activity compared to plasma-derived factor V 3
Alternative/Adjunctive Therapy
- Fresh frozen plasma (FFP) remains the traditional mainstay when platelets are unavailable 1, 2
- Antifibrinolytic agents (tranexamic acid, aminocaproic acid) provide benefit, especially for mucosal bleeding 2
Refractory Cases or Inhibitor Patients 2
- Recombinant activated factor VIIa (rFVIIa)
- Prothrombin complex concentrates (PCCs)
- Platelet transfusions (even in inhibitor patients)
- Immunosuppression (corticosteroids) for acquired inhibitors 3
Acquired Factor V Deficiency with Inhibitors
For patients with acquired inhibitors presenting with minor bleeding, withhold transfusions and prioritize inhibitor eradication with corticosteroids alone. 3
- Corticosteroids successfully eradicate inhibitors in most acquired cases 3
- Acquired inhibitors may develop secondary to antibiotics, bovine thrombin exposure, or autoimmune conditions 1, 3
Special Considerations
- No factor V-specific concentrate is currently available 2
- For patients presenting with thrombosis (paradoxically can occur with inhibitors), carefully assess risks/benefits of anticoagulation before treatment 3
- Prophylactic treatment is generally not required for mild deficiency 2
Future Therapies
Recombinant factor V products and advanced gene/cell therapies are under development but not yet clinically available 7