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PE26.7 | Hemophilia — SDL Guide (Part 2)

Management of Hemophilia

Management of hemophilia is centred on factor replacement therapy — supplying the missing coagulation factor to restore haemostatic function. The approach has evolved from purely on-demand (reactive) treatment to prophylactic (preventive) infusions in severe hemophilia, which is now the global standard of care because it prevents haemarthrosis and preserves joint function over decades.

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Dosing of factor replacement — the most examinable calculation:

For Hemophilia A (factor VIII):
> Factor VIII dose (units) = Desired rise in factor level (%) × Body weight (kg) × 0.5

Rationale: infusing 1 unit/kg of factor VIII raises the plasma level by approximately 2%, so the multiplier is 1/2 = 0.5.

For Hemophilia B (factor IX):
> Factor IX dose (units) = Desired rise in factor level (%) × Body weight (kg) × 1.0

Rationale: infusing 1 unit/kg of factor IX raises the plasma level by approximately 1% (a smaller volume-of-distribution correction for FIX), so the multiplier is 1.

Example: A 40 kg boy with hemophilia A has a haemarthrosis and baseline factor VIII of 2%. The target level for joint bleed is 50%. Dose = (50 − 2) × 40 × 0.5 = 48 × 40 × 0.5 = 960 units given as an IV infusion.

Indications and target levels: Minor bleeds (haemarthrosis, muscle haematoma) → target 30–50%; major bleeds (surgery, iliopsoas, head injury, life-threatening) → target 80–100%; prophylaxis in severe hemophilia → maintain trough >1% (usually achieved by thrice-weekly or alternate-day infusions).

Products available:
• Plasma-derived factor concentrates (virus-inactivated) — available in Indian haemophilia treatment centres.
• Recombinant factor concentrates (rFVIII, rFIX) — preferred in resource-adequate settings (no viral transmission risk).
• Cryoprecipitate — contains factor VIII, fibrinogen, von Willebrand factor; used when concentrates are unavailable.
• Fresh Frozen Plasma (FFP) — contains all coagulation factors but in low concentrations; volume-limited; inferior to concentrates for specific factor deficiency.

DDAVP (Desmopressin, 1-deamino-8-D-arginine vasopressin): Stimulates endothelial release of stored vWF and factor VIII, raising FVIII levels 3–6-fold within 30–60 minutes. Useful only in mild hemophilia A (patients with baseline FVIII 5–40%) for minor bleeds or pre-procedural cover — it has no role in hemophilia B (which involves FIX, not FVIII).

Adjuncts and general principles:
• Tranexamic acid (antifibrinolytic) — useful for oral mucosal bleeds, epistaxis, and dental procedures.
• Haemarthrosis management (RICE): Rest, Ice pack (cold compression), Compression bandage, Elevation of the affected limb — plus factor replacement.
• Physiotherapy between episodes: regular supervised exercise preserves joint strength and prevents contractures.
• Avoid aspirin and all NSAIDs — these impair platelet function and compound the haemostatic defect.
• Inhibitor management: Patients who develop inhibitors require either high-dose factor to overwhelm the antibody, bypassing agents (activated prothrombin complex concentrate, recombinant factor VIIa), or immune tolerance induction.
• Genetic counselling: All carrier females and their families should receive structured counselling regarding inheritance, carrier testing, and prenatal diagnosis options.

Self-Assessment

Consolidate your understanding with the following case and questions.

Case: A 10-year-old boy presents with right knee swelling and pain for three days following a minor fall. He reports that his maternal uncle had a 'bleeding disorder' requiring factor infusions. Examination: warm, swollen right knee with limited flexion; no petechiae or purpura; no lymphadenopathy; no hepatosplenomegaly. Investigations: Hb 10.8 g/dL (mild anaemia, likely from bleeding), WBC 9,200/µL (normal), platelets 280,000/µL, PT 13 s (normal), aPTT 82 s (reference <35 s), bleeding time normal. Factor VIII activity: 2%.

Q1: What is the diagnosis?
Answer: Hemophilia A — factor VIII deficiency confirmed at 2% (moderate-to-severe), X-linked recessive, with haemarthrosis of the knee.

Q2: Calculate the factor VIII dose to raise the level to 50% in this 35 kg boy.
Answer: Dose = (50 − 2) × 35 × 0.5 = 48 × 35 × 0.5 = 840 units IV.

Q3: The junior resident wants to give him paracetamol IM for the pain. What is your response?
Answer: Strictly contraindicated — IM injections must never be given in hemophilia. Prescribe oral/IV paracetamol only. Aspirin and NSAIDs must also be avoided.

Q4: What additional investigation would you order to look for a complication of repeated factor replacement?
Answer: Factor VIII inhibitor assay (Bethesda assay) — repeated FVIII infusions lead to inhibitor development in ~25–30% of severe hemophilia A patients. This should be checked if the aPTT fails to correct with factor replacement or if the mixing test shows non-correction.