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Hemophilia

Last updated: August 6, 2021

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Hemophilias are disorders of blood clotting and consequently may lead to serious bleeding. In the majority of cases, these disorders are hereditary. There are three types of hemophilia, determined based on which clotting factor is deficient: hemophilia A (factor VIII), hemophilia B (factor IX), and hemophilia C (factor XI). All types result in impaired secondary hemostasis (plasmatic coagulation) that manifests as increased activated partial thromboplastin time (aPTT). Hemophilia presents with hemarthrosis (bleeding into joints) and muscular or soft tissue hematomas. Depending on the remaining clotting factor activity, bleeding may occur spontaneously or in response to trauma of varying severity. Repeated hemarthrosis can eventually lead to joint destruction, a serious long-term complication of hemophilia. Diagnosis is based on patient history and a mix of semiquantitative and quantitative measurements of clotting factor activity. Severe hemophilia (enzyme activity < 1%) is treated with prophylactic substitution of clotting factors, whereas mild hemophilia A, in particular, can also be treated with desmopressin, a synthetic vasopressin analog.

Hemophilia is caused by an X-linked recessive defect (inherited or spontaneous mutation) or antibody production against clotting factors.

Hemophilia usually affects males, as it is primarily an X-linked recessive disease.

Severity Clinical signs Factor VIII or IX activity
Mild hemophilia Hematomas following severe trauma > 5% to < 50%
Moderate hemophilia Hematomas following mild trauma ≥ 1% to 5%
Severe hemophilia Spontaneous hematomas < 1%

Petechial bleeding is a common sign of platelet disorders, but NOT of coagulation disorders such as hemophilia.

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