Factor VIII inhibitor: Difference between revisions
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==Background== | ==Background== | ||
*Autoantibodies (IgG) directed against Factor VIII, causing an acquired coagulopathy | *Autoantibodies (IgG) directed against Factor VIII, causing an acquired coagulopathy | ||
*Also called | *Also called acquired hemophilia A — distinct from congenital [[hemophilia]] | ||
*Rare but potentially life-threatening; mortality 8-22% | *Rare but potentially life-threatening; mortality 8-22% | ||
* | *Associations: autoimmune diseases, malignancy, pregnancy/postpartum, medications (penicillin, sulfonamides), idiopathic (~50%) | ||
*Most common in elderly patients (median age 60-70) | *Most common in elderly patients (median age 60-70) | ||
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*Spontaneous soft tissue bleeding, ecchymoses, hematomas (often extensive) | *Spontaneous soft tissue bleeding, ecchymoses, hematomas (often extensive) | ||
*Mucosal bleeding, GI bleeding, [[hematuria]] | *Mucosal bleeding, GI bleeding, [[hematuria]] | ||
* | *Unlike congenital hemophilia: hemarthrosis is uncommon | ||
*May present with life-threatening hemorrhage without prior bleeding history | *May present with life-threatening hemorrhage without prior bleeding history | ||
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==Evaluation== | ==Evaluation== | ||
* | *Isolated prolonged PTT with normal PT and platelet count | ||
* | *Mixing study: PTT does NOT correct (distinguishes inhibitor from factor deficiency) | ||
*Factor VIII activity level markedly reduced | *Factor VIII activity level markedly reduced | ||
* | *Bethesda assay: Quantifies inhibitor titer (Bethesda Units) | ||
*CBC, fibrinogen, DIC panel to assess for concurrent coagulopathy | *CBC, fibrinogen, DIC panel to assess for concurrent coagulopathy | ||
==Management== | ==Management== | ||
* | *Acute bleeding: | ||
** | **Bypassing agents (first-line for significant hemorrhage): | ||
***Recombinant Factor VIIa (NovoSeven) 90 mcg/kg IV q2-3h | ***Recombinant Factor VIIa (NovoSeven) 90 mcg/kg IV q2-3h | ||
***Activated prothrombin complex concentrate (FEIBA) 50-100 units/kg IV q8-12h | ***Activated prothrombin complex concentrate (FEIBA) 50-100 units/kg IV q8-12h | ||
**High-dose Factor VIII concentrate may be tried but often ineffective if high-titer inhibitor | **High-dose Factor VIII concentrate may be tried but often ineffective if high-titer inhibitor | ||
**[[Desmopressin]] (DDAVP) for low-titer inhibitors only | **[[Desmopressin]] (DDAVP) for low-titer inhibitors only | ||
* | *Inhibitor eradication (in consultation with hematology): | ||
**Immunosuppression: corticosteroids ± cyclophosphamide | **Immunosuppression: corticosteroids ± cyclophosphamide | ||
**Rituximab for refractory cases | **Rituximab for refractory cases | ||
Latest revision as of 09:34, 22 March 2026
Background
- Autoantibodies (IgG) directed against Factor VIII, causing an acquired coagulopathy
- Also called acquired hemophilia A — distinct from congenital hemophilia
- Rare but potentially life-threatening; mortality 8-22%
- Associations: autoimmune diseases, malignancy, pregnancy/postpartum, medications (penicillin, sulfonamides), idiopathic (~50%)
- Most common in elderly patients (median age 60-70)
Clinical Features
- Spontaneous soft tissue bleeding, ecchymoses, hematomas (often extensive)
- Mucosal bleeding, GI bleeding, hematuria
- Unlike congenital hemophilia: hemarthrosis is uncommon
- May present with life-threatening hemorrhage without prior bleeding history
Differential Diagnosis
Coagulopathy
Platelet Related
- Too few
- Nonfunctional
Factor Related
- Acquired (Drug Related)
- Warfarin (Coumadin)
- Unfractionated heparin
- Low molecular weight heparin (i.e. enoxaparin (Lovenox), dalteparin)
- Factor Xa Inhibitors (e.g. rivaroxaban, apixaban, fondaparinux, edoxaban)
- Direct thrombin inhibitors (e.g. dabigatran, argatroban, bivalirudin)
- Illness induced
- Genetic
Evaluation
- Isolated prolonged PTT with normal PT and platelet count
- Mixing study: PTT does NOT correct (distinguishes inhibitor from factor deficiency)
- Factor VIII activity level markedly reduced
- Bethesda assay: Quantifies inhibitor titer (Bethesda Units)
- CBC, fibrinogen, DIC panel to assess for concurrent coagulopathy
Management
- Acute bleeding:
- Bypassing agents (first-line for significant hemorrhage):
- Recombinant Factor VIIa (NovoSeven) 90 mcg/kg IV q2-3h
- Activated prothrombin complex concentrate (FEIBA) 50-100 units/kg IV q8-12h
- High-dose Factor VIII concentrate may be tried but often ineffective if high-titer inhibitor
- Desmopressin (DDAVP) for low-titer inhibitors only
- Bypassing agents (first-line for significant hemorrhage):
- Inhibitor eradication (in consultation with hematology):
- Immunosuppression: corticosteroids ± cyclophosphamide
- Rituximab for refractory cases
- Avoid procedures and IM injections; hold anticoagulants
Disposition
- Admit all patients — hematology consult urgently
- ICU for significant hemorrhage