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Group of hereditary disorders in which affected individuals fail to make enough of certain proteins needed to form blood clots.

PubMed Health Glossary
(Source: NIH - National Cancer Institute)


Hemophilia (heem-o-FILL-ee-ah) is a rare bleeding disorder in which the blood doesn't clot normally.

If you have hemophilia, you may bleed for a longer time than others after an injury. You also may bleed inside your body (internally), especially in your knees, ankles, and elbows. This bleeding can damage your organs and tissues and may be life threatening.


Hemophilia usually is inherited. "Inherited" means that the disorder is passed from parents to children through genes.

People born with hemophilia have little or no clotting factor. Clotting factor is a protein needed for normal blood clotting. There are several types of clotting factors. These proteins work with platelets (PLATE-lets) to help the blood clot.

Platelets are small blood cell fragments that form in the bone marrow - a sponge-like tissue in the bones. Platelets play a major role in blood clotting. When blood vessels... Read more about Hemophilia

What works? Research summarized

Evidence reviews

Cumulative inhibitor incidence in previously untreated patients with severe hemophilia A treated with plasma-derived versus recombinant factor VIII concentrates: a critical systematic review

Inhibitor development represents currently the most serious and challenging complication of clotting factor replacement therapy. A number of studies have analyzed the impact of the type of factor VIII (FVIII) replacement therapy (plasma-derived versus recombinant concentrates) on inhibitor development in hemophilia A patients with conflicting results. In order to shed light on this controversial issue, we performed a systematic review and meta-analysis on the published prospective studies evaluating the incidence rate of inhibitors in previously untreated patients (PUPs) with severe hemophilia A. Data from a total of 800 patients enrolled in 25 prospective studies published between 1990 and 2007 were included in this review. The quality of the studies was evaluated using two different systems: the Newcastle-Ottawa Scale (NOS) and STrengthening the Reporting of OBservational studies in Epidemiology (STROBE). Overall, the inhibitor incidence rate did not differ significantly between recipients of plasma-derived and recombinant FVIII concentrates (weighted means: 21%; 95% CI, 14-30 versus 27%; 95% CI, 21-33). Similarly, high titer inhibitors did not differ significantly between patients treated with plasma-derived (weighted means: 14%; 95% CI, 8-25) or recombinant FVIII concentrates (weighted means: 16%; 95% CI, 13-20). Thus, the main conclusion of this systematic review performed using selective criteria is that the type of FVIII product (i.e., plasma-derived versus recombinant FVIII concentrates) does not seem to influence the inhibitor rate in PUPs with severe hemophilia A.

Surgery and inhibitor development in hemophilia A: a systematic review

BACKGROUND: Although the association between intensive treatment and the formation of inhibiting antibodies towards factor VIII (FVIII) in hemophilia A has been demonstrated, the contributing effect of surgery is presently unclear. The release of immunological danger signals resulting from tissue damage during surgery in the presence of a high FVIII antigen load may elicit the formation of FVIII antibodies. The aim of this systematic review was to investigate the role of surgery in the inhibitor risk associated with intensive treatment as compared with treatment for bleeding and prophylactic administration of FVIII.

Use of recombinant activated factor VII in patients without hemophilia: a meta-analysis of randomized control trials

This review evaluated the benefits and harms of treatment with recombinant activated factor VII in non-haemophilia patients. The authors concluded that treatment reduced the need for blood transfusion and may reduce mortality. Therapeutic doses limited to 90υg/kg may be the most appropriate treatment regimen. The authors' conclusion reflected the evidence presented and appears reliable.

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Summaries for consumers

Treatments for acute bleeds in people with acquired hemophilia A

Acquired hemophilia A is a rare but severe bleeding disorder caused by the autoantibody directed against factor VIII (FVIII, a blood clotting protein) in patients with no previous history of a bleeding disorder. This bleeding disorder occurs more frequently in the elderly and may be associated with several other conditions, such as solid tumours, autoimmune diseases, or with drugs; it is also sometimes associated with pregnancy. However, in about half of the cases the causes are unknown. Bleeding occurs in the skin; mucous membranes; and muscles; with joint bleeds being unusual. Therapies for acquired hemophilia A include treatments to stop acute bleeds and to destroy the FVIII autoantibodies. Acute bleeds can be treated with recombinant activated FVII or activated prothrombin complex concentrate (aPCC). If these are unavailable, FVIII concentrates or 1‐desamino‐8‐D‐arginine‐vasopressin (DDAVP) fresh frozen plasma can be attempted; however, these last two options are not usually effective, and it is not known if one of these products is better than the other.

Regular clotting factor replacement therapy to prevent joint disease in people with severe hemophilia A or B

Hemophilia A and B are X‐linked inherited bleeding disorders, in which the major clinical problem is repeated bleeding into joints. As this disorder progresses, joints become deformed and movement limited. Current therapy for treating and preventing bleeding includes plasma‐derived or recombinant clotting factor concentrates. This review includes six randomised controlled trials. Two compare the regular use of clotting factor concentrates to prevent joint bleeds with their use 'on demand'. Four compare different regimens of regular use in children and adults with hemophilia. It was clearly evident that preventative therapy, as intravenous infusion of factor concentrate repeated more times a week and started early in childhood was able to reduce joint deterioration as compared to treatment administered after bleeding occurred. This favourable effect is due to a consistent reduction in total bleeds and hemarthrosis (bleeding into joints) and leads to a significant improvement in quality of life. Preventative therapy is linked to an increased factor usage and cost of treatment. We found weaker evidence (due to lack of data) to show preventative therapy reduced joint deterioration when treatment is started after joint damage has been established. Further studies are needed to establish the best preventative regimen, i.e. for example starting time, dosage frequency, minimally effective dose.

Gene therapy for haemophilia

Haemophilia is a bleeding disorder caused by defective genes that produce abnormal blood clotting proteins. Gene therapy replaces these defective genes with normal ones. We looked for trials that used this approach of replacing defective genes for producing normal blood clotting proteins the treatment of haemophilia. As of 06 November 2014, we found no trials to provide reliable evidence about the risks or benefits of gene therapy for haemophilia. There is a need for trials that assess the long‐term feasibility, success and risks of gene therapy for people with haemophilia.

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Terms to know

Blood Plasma
The clear, yellowish, fluid part of the blood that carries the blood cells. The proteins that form blood clots are in plasma.
Erythrocytes (Red Blood Cells)
A cell that carries oxygen to all parts of the body.
Inherited; having to do with information that is passed from parents to offspring through genes in sperm and egg cells.
Leukocytes (White Blood Cells)
A type of immune cell. Most white blood cells are made in the bone marrow and are found in the blood and lymph tissue. White blood cells help the body fight infections and other diseases. Granulocytes, monocytes, and lymphocytes are white blood cells.
Platelets (Thrombocytes)
A tiny piece of cell that is made by breaking off of a large cell in the bone marrow. Platelets are found in the blood and spleen. They help form blood clots to slow or stop bleeding, and to help wounds heal. Also called thrombocyte.

More about Hemophilia

Photo of a young adult man

Also called: Haemophilia, Hemophilia A (Factor VIII deficiency, Classic hemophilia), Hemophilia B (Factor IX deficiency, Christmas disease)

Other terms to know: See all 5
Blood Plasma, Erythrocytes (Red Blood Cells), Genetic

Related articles:
Factor IX Injection

Keep up with systematic reviews on Hemophilia:


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