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Advances in Hemophilia Therapies - Part 1

Guy Young, MD, Parul Bhatia, MD, and Solomon Behar, MD
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Pediatric hematologist and hemophilia researcher Dr Guy Young reviews with Parul and Sol presentations, complications and treatment of hemophilia.

Pearls:

  • Close to 70% of patients with hemophilia have a known family history.

  • Factor replacement therapy is the current mainstay of treatment for hemophilia patients. It is used to both treat acute bleeding episodes but also as prophylaxis to prevent bleeding.  

  • Each unit of factor VIII per kg raises the  factor level by about 2%. Whereas each unit of factor IX per kg raises the factor level by about 1%.

  • The goal of prophylaxis with factor replacement therapy is to to prevent hemophilic arthropathy, which is permanent and debilitating joint damage caused by repeated hemarthrosis.

 

  • What is hemophilia?  It is a bleeding disorder due to a deficiency of either clotting factor VIII (hemophilia A) or factor IX (hemophilia B). It is uncommon,  occurring in about one out of 10,000 individuals. It is transmitted in an x-linked recessive fashion, which means that it affects primarily males. Females can be  carriers of hemophilia.

  • Hemophilia can be categorized into three categories:

    • 1.  Severe hemophilia where the factor VIII or factor IX level is below the lab’s level of quantitation. In other words, zero or less than 1%.

    • 2.  In moderate hemophilia, the factor VIII or factor IX  level is between 1% and 5%.

    • 3.  Mild hemophilia is 6% to 40% of the normal level of factor VIII or factor IX.

  • How do patients with hemophilia come to presentation? The timing of presentation as well how the patient presents will depend on the severity of his/her disease.

    • Family history.  About 70% of patients with hemophilia have a known family history. If a patient has a family history, then subsequent siblings or subsequent children that are born are at risk of having hemophilia as well.

    • Excessive bleeding. Patients who have severe hemophilia will almost always present in the first year of life often within the first days of life, secondary to excessive bleeding from things such as heel sticks and circumcisions. Cephalohematomas, which can occur in normal children, should also make someone think about a bleeding disorder.

    • Bruising. Excessive number of bruises, unusually large bruises, or atypical locations for bruises raise the concern for a bleeding disorder. The bruises are noticed first when the child starts to engage in activities such as crawling, cruising, and eventually,  walking, and falling. This could occur as early as six months of age, but more commonly towards one year of age when kids start to really become mobile.

  • What is the current treatment option for patients with hemophilia? Factor replacement. If the patient is  missing factor VIII, factor VIII is given. If the patient is missing factor IX, factor IX is given.

  • What are the  downsides of factor replacement therapy? They primarily relate to the fact that factor replacement therapies  are formulated from protein.

    • They must must be given intravenously as they are not well absorbed from the subcutaneous tissue or intramuscular tissue.

    • These therapies have short half-lives. In order to maintain a desired factor level, whether it is to treat a bleed or to prevent bleeding altogether (i.e. prophylaxis),  it often requires multiple infusions. For those receiving  prophylactic factor replacement, there are some formulationes that can be administered once weekly but more commonly, a patient with severe hemophilia will need two to three IV infusions every week.

    • Given the need for repeated IV infusions, many children need a central venous catheter, which places them at risk for central line associated complications such as infections, malfunction and bleeding.

  • Which hemophilia patient requires prophylaxis?  Patient with severe hemophilia, those with undetectable factor levels, and even up to 25% of the moderate hemophiliacs who are phenotypically severe,  get prophylactic factor replacement. The goal of prophylaxis with factor replacement is to to prevent hemophilic arthropathy, which is permanent and debilitating joint damage caused by repeated bleeding into the joint space (i.e. hemarthrosis).

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Land of the Rising Fontanelle Full episode audio for MD edition 188:47 min - 89 MB - M4AHippo Peds RAP July 2018 Written Summary 395 KB - PDF