Ver el código de «Factor VIII inhibitor»

==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==
{{Increased bleeding DDX}}

==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
*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

==See Also==
*[[Hemophilia]]
*[[Coagulopathy (Main)]]
*[[DIC]]

==References==
<references/>

[[Category:Heme/Onc]]