Haemophilia A and B
X-linked factor VIII and IX deficiency. Severity by factor level, the isolated long APTT, treating suspected head bleeds before imaging, factor dosing, emicizumab and its lab effects, desmopressin in mild haemophilia A, inhibitors, carriers, and acquired haemophilia A.
Tier 2Condition
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- X-linked recessive deficiency of factor VIII (haemophilia A, about 1 in 5,000 males) or factor IX (haemophilia B, about 1 in 25,000). A third of cases have no family history.
- Clinically identical. Initiation of coagulation works, but propagation fails, so clots are slow and friable (see coagulation physiology).
- Isolated prolonged APTT with normal PT, platelets and fibrinogen. A normal APTT doesn't exclude mild disease.
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Sources
- WFH Guidelines for the Management of Hemophilia, 3rd editionSrivastava A et al., Haemophilia 2020;26 Suppl 6:1-158, 2020
- The WFH Guidelines for the Management of Haemophilia: AAV Gene Therapy, 2025Pierce GF, Ozelo MC, Mahlangu J et al., Haemophilia 2026;32(1):20-54 (online 25 October 2025), 2025
- Australian Bleeding Disorders Registry annual report 2024-25AU/NZNational Blood Authority, 2024-25
- Rebalancing therapiesAU/NZHaemophilia Foundation Australia
- Australian public assessment report for Hemgenix (etranacogene dezaparvovec)AU/NZTherapeutic Goods Administration, 2024
- Emicizumab prophylaxis in hemophilia A with inhibitors (HAVEN 1)Oldenburg J et al., N Engl J Med 2017;377:809-18, 2017
- Activated prothrombin complex concentrate in patients receiving emicizumab prophylaxis: from evidence to clinical practice (guidelines: no more than 50 U/kg per dose and 100 U/kg per day)Sidonio RF et al., Res Pract Thromb Haemost 2025;9:102926, 2025
- International recommendations on the diagnosis and treatment of acquired hemophilia ATiede A et al., Haematologica 2020;105:1791-801, 2020
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Turnstile bot check on sign-in and signed-out feedback