Hemophilia
A genetic bleeding disorder where the blood doesn't clot properly due to missing clotting factors, leading to frequent bleeding into joints and muscles.
Emergency Management: Intracranial hemorrhage, neck/throat bleeding (airway compromise), compartment syndrome from muscle bleeding.
Hemophilia is an inherited, X-linked recessive bleeding disorder caused by a deficiency or dysfunction of specific coagulation factors. Hemophilia A involves a deficiency in Factor VIII (FVIII), while Hemophilia B (Christmas Disease) involves a deficiency in Factor IX (FIX). This deficiency disrupts the intrinsic pathway of the coagulation cascade, resulting in an inability to form a stable fibrin clot and leading to prolonged, spontaneous, or trauma-induced bleeding.
Detailed Overview
Hemophilia primarily affects males, though females can be symptomatic carriers. The clinical hallmark is deep tissue bleeding, specifically into joints (hemarthrosis) and muscles. Without prophylactic treatment, recurrent joint bleeding causes a destructive inflammatory arthropathy. The clinical significance of hemophilia has evolved dramatically; previously a fatal disease in early adulthood, prophylactic factor replacement and novel non-factor therapies (like emicizumab) now allow patients to lead near-normal lifespans, shifting the clinical focus from acute hemorrhage control to preventing long-term joint damage and managing treatment complications, such as the development of neutralizing antibodies (inhibitors).
Epidemiology & Demographics
Hemophilia A is the most common severe inherited bleeding disorder, occurring in 1 in 5,000 live male births. Hemophilia B occurs in 1 in 30,000 live male births. Affects all racial and ethnic groups equally.
Etiological Mechanism
Caused by mutations in the F8 gene (Hemophilia A) or F9 gene (Hemophilia B) located on the X chromosome (Xq28 and Xq27.1, respectively). An intron 22 inversion in the F8 gene accounts for nearly 50% of severe Hemophilia A cases. Approximately 30% of cases represent de novo (spontaneous) mutations without a family history.
Primary Causes
Inherited X-linked recessive mutation. Spontaneous acquired hemophilia is a distinct, rare autoimmune condition caused by autoantibodies against Factor VIII.
Hemostasis involves primary hemostasis (platelet plug formation) and secondary hemostasis (coagulation cascade leading to a fibrin mesh). Hemophiliacs have normal primary hemostasis (normal platelets/vWF), so they may not bleed excessively from minor superficial cuts. However, FVIII and FIX form the 'tenase' complex in the intrinsic pathway, which is required to amplify thrombin generation. The deficiency prevents adequate fibrin formation. When capillaries in highly vascular synovial joints are subjected to normal daily microtrauma, the fragile clots fail. Blood enters the joint space (hemarthrosis). Iron from degraded red blood cells is taken up by synovial macrophages, triggering severe synovial inflammation, hyperplasia, and the release of proteases that aggressively destroy articular cartilage and bone.
Diagnostic Criteria & Guidelines
Prolonged Activated Partial Thromboplastin Time (aPTT) with a normal Prothrombin Time (PT) and normal Platelet count. Mixing study corrects the aPTT (unless inhibitors are present). Definitive diagnosis requires specific factor assays showing reduced FVIII or FIX activity levels.
For Severe Hemophilia A Prophylaxis: Emicizumab (a bispecific monoclonal antibody mimicking FVIII) given subcutaneously weekly (1.5 mg/kg) or every 2-4 weeks. Alternatively, prophylactic Recombinant FVIII infusions 3 times weekly. Acute bleeding requires rapid IV infusion of FVIII concentrate to achieve 50-100% factor activity.
Second-Line & Adjunctive Therapy
For mild Hemophilia A: Desmopressin (DDAVP) 0.3 mcg/kg IV or intranasal can transiently release endogenous FVIII and vWF from endothelial cells for minor bleeds. For patients with high-titer inhibitors (>5 BU): Bypassing agents are required, such as Recombinant Factor VIIa (NovoSeven) 90 mcg/kg IV.
Surgical & Procedural Management
Synovectomy (chemical, radioisotopic, or arthroscopic) to remove inflamed synovium in target joints and reduce recurrent bleeding. Joint arthroplasty (replacement) for end-stage arthropathy.
Patient Counseling & Advice
Educate the patient and family on recognizing early signs of joint bleeding ('aura' or tingling) and self-administering factor therapy immediately. Genetic counseling for family planning.
Follow-Up & Monitoring Schedule
Annual comprehensive care clinic visits (Hematologist, Orthopedist, Physical Therapist). Monitor inhibitor titers annually or if clinical response to factor replacement declines.
Preventive Strategies
Primary prophylaxis (starting factor replacement or Emicizumab before the 2nd joint bleed or by age 3) is the standard of care to prevent joint damage.
With modern prophylaxis, patients have a near-normal life expectancy and can avoid severe arthropathy. However, inhibitor development represents a significant complication that increases morbidity.