✅ Model Answer:
• Diagnosis: Von Willebrand disease (VWD) type 1 – quantitative deficiency of VWF. Mildly prolonged PTT, low factor VIII (25 IU/dL).
• Any other test: VWF:Ag (antigen), VWF:RCo (ristocetin cofactor activity), VWF multimer analysis, bleeding time (PFA-100), and von Willebrand factor propeptide (to assess clearance).
• What to do next: Desmopressin (DDAVP) 0.3 mcg/kg IV or intranasal (Stimate) for bleeding/ menorrhagia. For severe bleeding or DDAVP failure: VWF-containing concentrate (Humate-P). Tranexamic acid for mucosal bleeding.
• Follow-up plan: Monitor VWF levels and response to DDAVP. Manage menorrhagia with oral contraceptives or tranexamic acid. Avoid aspirin/NSAIDs. If future surgery, DDAVP test dose and factor level monitoring.

✅ Model Answer:
• Gene: VWF gene located on chromosome 12 (12p13.3).
• Inheritance:
- Type 1: Autosomal dominant (most common).
- Type 2: Autosomal dominant or recessive (depending on subtype).
- Type 3: Autosomal recessive (severe).
• Mutations: More than 500 mutations identified. Most common: missense mutations leading to quantitative or qualitative defects.
• Protein: Von Willebrand factor (VWF) is a multimeric glycoprotein essential for platelet adhesion and protection of factor VIII from degradation.

✅ Model Answer:
• Mucocutaneous bleeding: (most common)
- Epistaxis: Frequent nosebleeds (especially in children).
- Easy bruising: Spontaneous or minor trauma.
- Menorrhagia: Heavy menstrual bleeding (common in adolescent females).
- Gingival bleeding: After brushing or dental procedures.
- Gastrointestinal bleeding: Less common.
• Post-surgical bleeding: Prolonged bleeding after circumcision, dental extractions, or surgery.
• Hemarthrosis: Rare (unlike hemophilia).
• Severity: Variable — type 1 (mild-moderate), type 2 (moderate), type 3 (severe).

✅ Model Answer:
• Initial screening:
- PT: Normal.
- PTT: Mildly prolonged (if factor VIII <30-40%).
- Platelet count: Normal.
• Specific VWD tests:
- VWF:Ag: VWF antigen level (quantitative).
- VWF:RCo: Ristocetin cofactor activity (functional assay).
- Factor VIII assay: Low in type 1 and type 3.
- VWF multimer analysis: To differentiate type 2 subtypes.
- Bleeding time (PFA-100): Prolonged in most cases.
- Genetic testing: VWF gene mutation analysis (for confirmation and family screening).
• Important: VWF levels can be influenced by blood group (O blood type lower), stress, and inflammation.

✅ Model Answer:
• Desmopressin (DDAVP):
- Mechanism: Releases endogenous VWF from endothelial cells.
- Dose: 0.3 mcg/kg IV (or intranasal Stimate 150 mcg).
- Indication: Type 1 VWD (responders), mild type 2.
- Test dose: Administer before surgery to assess response.
• VWF-containing concentrates:
- Humate-P (VWF/FVIII concentrate): For severe bleeding, surgery, or DDAVP non-responders.
- Dose: Based on VWF:RCo units (50-80 IU/kg).
• Antifibrinolytics:
- Tranexamic acid: 25-50 mg/kg/day for mucosal bleeding (menorrhagia, epistaxis).
- Epsilon-aminocaproic acid: Alternative.
• Avoid: Aspirin, NSAIDs, antiplatelet agents.

✅ Model Answer:
• Anemia: Due to chronic blood loss (menorrhagia, GI bleeding).
• Iron deficiency anemia: Common in adolescents with menorrhagia.
• Joint bleeding: Rare but can occur in severe type 3.
• Post-surgical bleeding: If undiagnosed before surgery.
• Pregnancy complications: May worsen bleeding during delivery or postpartum.
• Acquired VWD: Can occur in autoimmune disorders, lymphoproliferative diseases, or certain drugs (rare).
• No increased risk of thrombosis (unlike some other bleeding disorders).

✅ Model Answer:
• Prognosis:
- Excellent for type 1 with appropriate management.
- Type 3: Severe disease, requires regular VWF replacement.
- Life expectancy: Normal with proper treatment.
- Morbidity: Mainly from menorrhagia (iron deficiency) and bleeding complications.
• Long-term follow-up:
- Monitor VWF levels: Especially before surgery or during pregnancy.
- Manage menorrhagia: Oral contraceptives, tranexamic acid, or VWF replacement.
- Iron supplementation: For anemia.
- Education: Avoid aspirin/NSAIDs, recognize bleeding signs.
- Genetic counseling: For family members (autosomal dominant/recessive).

✅ Model Answer:
• Mechanism: DDAVP stimulates release of VWF from endothelial cells and increases factor VIII levels.
• Indications:
- Type 1 VWD: First-line treatment for mild-moderate bleeding or prophylaxis before minor procedures.
- Mild type 2 VWD: Some subtypes respond (test dose required).
- Not effective: Type 3 VWD (no VWF stores).
• Routes:
- IV: 0.3 mcg/kg (peak effect at 30-60 minutes).
- Intranasal: Stimate 150 mcg (for adolescents and adults).
• Test dose: Administer before surgery to confirm response (measure VWF and FVIII levels).
• Side effects: Flushing, headache, hyponatremia (monitor fluids).
• Duration: Effect lasts 6-12 hours.