P PERS RAISED INR

 A

In the context of a “factor V problem” with a persistently raised INR, it’s important to distinguish which Factor V condition is being discussed, because they behave very differently.

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Key point upfront

Factor V Leiden does not cause a raised INR.
A persistently elevated INR points instead toward Factor V deficiency, an acquired Factor V inhibitor, or another disorder affecting the coagulation pathway.

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How Factor V relates to INR

• INR reflects the extrinsic and common pathways of coagulation

• Factor V is part of the common pathway, so problems with Factor V can prolong INR

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Conditions involving Factor V

1. Factor V Leiden (most common “Factor V problem”)

• Genetic mutation causing resistance to activated protein C

• Leads to increased clotting (thrombophilia)

• PT/INR is normal

• Patients get DVT/PE, not bleeding

➡️ If INR is elevated, this is NOT the cause

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2. Congenital Factor V deficiency (Owren disease)

• Rare bleeding disorder

• Causes:

  • Prolonged PT/INR

  • Prolonged aPTT

• Symptoms:

  • Easy bruising

  • Mucosal bleeding

  • Surgical bleeding

• INR remains persistently elevated unless treated

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3. Acquired Factor V inhibitor

• Autoantibody against Factor V

• Can occur after:

  • Surgery

  • Antibiotics

  • Autoimmune disease

  • Malignancy

• Causes:

  • Sudden, persistent elevation of INR

  • Bleeding risk

• Mixing studies fail to correct INR

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4. Other causes often mistaken for “Factor V problem”

These must be excluded:

Cause	INR
Liver disease	↑
Vitamin K deficiency	↑
Warfarin exposure	↑
DIC	↑
Massive transfusion	↑

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How clinicians sort this out

Typical workup:

1. PT/INR and aPTT

2. Mixing study

   • Correction → factor deficiency

   • No correction → inhibitor

3. Factor V activity level

4. Inhibitor assay (if suspected)

5. Liver function tests, vitamin K status

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Summary

• Factor V Leiden ≠ elevated INR

• Persistently raised INR + Factor V issue suggests:

  • Factor V deficiency

  • Acquired Factor V inhibitor

  • Or another systemic cause (especially liver disease)

• This is a bleeding risk, not a clotting disorder

If you want, you can tell me:

• Whether this is congenital or acquired

• PT vs aPTT pattern

• Whether a mixing study was done

and I can walk through the interpretation step by step.