More On Treatment And Prophylaxis Of Hemophilia A And The Christmas Disease (Hemophilia B)
A General Overview
Freeze dried AHG is available from several laboratories. Each vial contains 250 to 1000 units. It is more concentrated and purified and it remains potent for 18 months. In the ordinary case, the initial dose should be 250- 1000 units depending on the severity of the bleeding. Larger initial doses are more effective. A formula has been used to calculate the requirement of factor VIII concentrates.
K (rise in factor VIII concentration in the patient’s plasma produced for each unit/Kg of infused material) = Patient’s weight (Kg) X desired rise in factor VIII (%)/Units of factor VIII in the dose administered.
Factor VIII inhibitors may develop as a result of repeated administration of AHG. These neutralize factor VIII:C and render administered factor VIII concentrates ineffective. In such subjects, AHG made from porcine plasma is effective and nonantigenic. At present, prothrombin complex concentrates (PCC) are available. These have factor VIII bypassing activity and they may be effective even in those having antibodies to factor VIII:C. Their use is still controversial. Recent reports suggest the possible role of repeated administration of AHG concentrates in conferring acquired immunodeficiency state (AIDS) in hemophilics. Cryoprecipitate is devoid of this risk. If factor VIII concentrates are not available, fresh frozen plasma is the next best alternative. Fresh blood should be used to replace the lost blood.
Antifibrinolytic drugs like epsilon-aminocaproic acid (EACA) given in doses of 24g daily or tranexamic acid 10 mg have been used along with AHG to prevent dissolution of the clots formed as a result of therapy. Mild cases of hemophilia respond to 1-deamino-8-D- arginine vasopressin (DDAVP) and this form of therapy is gaining acceptance. Intravenous administration of DDAVP in a dose of 0.3 ug/Kg slowly in patients with factor VIII:C levels of 10% or more is advised. If the factor VIII:C level is lower, DDAVP is not useful.
Manifestations Of Hemophilia B
All hemophilics should carry identification cards showing their blood groups to enable emergency treatment without delay. They should be made aware of the nature of the disease and its management. Children should attend ordinary schools but should avoid games and physical training. Special care should be taken to avoid all trauma. Intramuscular injections and antiplatelet drugs should be acoided in all hemophilics. Dental care should be instituted to avoid dental caries and the need for extractions.
Several blood transfusion centers have adopted home treatment programmes. The patient or his near relative is instructed to identify bleeding episodes and self-administer AHG early. This prevents further bleeding and joint deformity.
Prenatal diagnosis of hemophilia is possible by estimating factor VIII:C in fetal blood obtained by fetoscopy. Affected pregnancy can be aborted. Carrier females can be detected by VIII:C assay. Such females show only half, the VIII:C activity expected for the level of VIII.R.AG.
Occasionally, a non-hemophilic subject may acquire antibodies against factor VIII:C as in systemic lupus erythematosus. Such a subject develops bleeding tendency as a hemophilic.
Christmas Disease (Hemophilia B)
This also is an X-liked recessive disorder transmitted by females and manifested in males. The genetic defect is located in the X-chromosome and it is different from that of hemophilia A. The manifestations resemble those of mild hemophilia. This disease accounts for 20-25% of the inherited coagulation defects in India. Factor IX is absent or functionally defective. Diagnosis can be made by factor IX assay. Thromboplastin generation test reveals a defect in patient’s serum. Treatment is to give fresh frozen plasma once in 24 hours.
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