18-month-old boy with severe hemophilia A

100%

Educational Objective:

Identify target levels for factor replacement.

Key Point:

The target level of factor activity after replacement for a serious injury is 100%.

Explanation:

In a patient with hemophilia who has a life-threatening injury or major hemorrhage, factors should be replaced to raise the factor level to 100% activity. For mild to moderate bleeding, factors levels should be replaced to aim for a level between 35% and 50%.

Hemophilia is a coagulopathy caused by factor VIII deficiency (hemophilia A) or factor IX deficiency (hemophilia B). These 2 types are X-linked recessive disorders, and patients present with prolonged partial thromboplastin time.

Hemophilia A and B are the most common severe inherited bleeding disorders. Hemophilia A is due to a deficiency of factor VIII and hemophilia B to a deficiency of factor IX. The inadequate formation of thrombin leads to failure to form a tight fibrin clot. Partial thromboplastin time is prolonged.

Children with hemophilia may hemorrhage with circumcision or during venipuncture, or they may develop joint or intracranial bleeding with minor injuries. The condition is diagnosed by measuring factor VIII and IX levels. Treatment for moderate to severe bleeding is with factor supplementation.

Reference:

Scott JP, Flood VH. Hereditary clotting factor deficiencies (bleeding disorders). In: Kliegman RM, et al, eds. Nelson Textbook of Pediatrics. 20th ed., 2016:2384-2389.