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| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
Factor VIII Inhibitor, Chromogenic
Test Code15586
Preferred Specimen
Instructions:
Platelet-poor plasma: Centrifuge light blue-top tube for 15
minutes at approximately 1500g within 60 minutes of
collection. Using a plastic pipette, remove plasma, taking
care to avoid the WBC/platelet buffy layer and place into
a plastic vial. Centrifuge a second time and transfer
platelet poor plasma into a new plastic vial. Plasma must
be free of platelets (<10,000/uL). Freeze immediately and
ship on dry ice.
Reject Criteria:
Gross hemolysis, Grossly icteric, Grossly lipemic
PREFERRED
2 mL frozen plasma in each of three (LB, light blue-top
tubes, sodium citrate), frozen
Minimum: 1 mL
RT: Unacceptable
Refrigerated (cold packs): Unacceptable
Frozen -20 degrees C: 14 days
Frozen -70 degrees C: 1 year
Platelet-poor plasma: Centrifuge light blue-top tube for 15
minutes at approximately 1500g within 60 minutes of
collection. Using a plastic pipette, remove plasma, taking
care to avoid the WBC/platelet buffy layer and place into
a plastic vial. Centrifuge a second time and transfer
platelet poor plasma into a new plastic vial. Plasma must
be free of platelets (<10,000/uL). Freeze immediately and
ship on dry ice.
Reject Criteria:
Gross hemolysis, Grossly icteric, Grossly lipemic
PREFERRED
2 mL frozen plasma in each of three (LB, light blue-top
tubes, sodium citrate), frozen
Minimum: 1 mL
RT: Unacceptable
Refrigerated (cold packs): Unacceptable
Frozen -20 degrees C: 14 days
Frozen -70 degrees C: 1 year
Methodology
Chromogenic
Setup Schedule
Wednesday, Sunday Afternoon
Report available: 2 Days
Report available: 2 Days
Reference Range
<0.6 BU/mL
Clinical Significance
Patients with severe and moderate hemophilia often need
specific substitution therapy with plasma derived or
recombinant Factor VIII concentrates. About 15-35 % of
hemophiliacs treated with FVIII concentrates develop
specific alloantibodies against human FVIII (inhibitors).
The development of functionally inhibiting alloantibodies
in hemophilia represents a serious clinical problem. In
some patients, infusion of excessive amounts of Factor
VIII may be utilized to overcome the antibody. However,
this may result in an increased titer of the inhibitor
leaving the patient unresponsive to further treatment.
Therefore, detection and quantitation of inhibitors is of
great importance in the care of these patients.
In non-hemophiliacs, development of circulating FVIII
inhibitors can lead to acquired hemophilia, a rare
bleeding disorder with an incidence of 1 per 106 persons
per year. Acquired hemophilia can develop in patients
with immunologic disorders such as rheumatoid arthritis,
postpartum women, and in older individuals with no
underlying disease.
Inhibitors to Factor VIII have been denoted as high- or
low-responses based on the amnestic response of the
antibody to antigenic challenge. Alloantibodies, which
demonstrate an increase in titer, have been termed
high-response inhibitors while those that do not have
been termed low response inhibitors. An antibody which is
persistently 5 Bethesda units per mL (BU/mL) despite
repeated challenge with substitution factor concentrate
should be termed as low-response inhibitor, whereas the
term high-response inhibitor should be applied to cases
where the inhibitory activities have been >5 BU/mL at any
time.
Factor VIII Activity and Factor VIII Inhibitor give a
quantitative value for inhibitor activity in the
determination of treatment options and the Nijmegen gives
a more accurate value to low titer inhibitors which
impacts treatment options.
Unlike other tests which use human coagulation Factors IX
and X, the reagents used in this test contain bovine
Factors IX and X. In patients being treated with
Emicizumab (Hemlibra), the drug will interact with
activated Factor IX and factor X, which will result in
Factor X being activated in the absence of Factor VIII
activity. This could result in a false negative result,
as even in the presence of Factor VIII inhibitors
Emicizumab will cause the coagulation cascade to proceed.
Emicizumab does not interact with bovine factors
therefore there is no risk of Emicizumab interference
with this test.
specific substitution therapy with plasma derived or
recombinant Factor VIII concentrates. About 15-35 % of
hemophiliacs treated with FVIII concentrates develop
specific alloantibodies against human FVIII (inhibitors).
The development of functionally inhibiting alloantibodies
in hemophilia represents a serious clinical problem. In
some patients, infusion of excessive amounts of Factor
VIII may be utilized to overcome the antibody. However,
this may result in an increased titer of the inhibitor
leaving the patient unresponsive to further treatment.
Therefore, detection and quantitation of inhibitors is of
great importance in the care of these patients.
In non-hemophiliacs, development of circulating FVIII
inhibitors can lead to acquired hemophilia, a rare
bleeding disorder with an incidence of 1 per 106 persons
per year. Acquired hemophilia can develop in patients
with immunologic disorders such as rheumatoid arthritis,
postpartum women, and in older individuals with no
underlying disease.
Inhibitors to Factor VIII have been denoted as high- or
low-responses based on the amnestic response of the
antibody to antigenic challenge. Alloantibodies, which
demonstrate an increase in titer, have been termed
high-response inhibitors while those that do not have
been termed low response inhibitors. An antibody which is
persistently 5 Bethesda units per mL (BU/mL) despite
repeated challenge with substitution factor concentrate
should be termed as low-response inhibitor, whereas the
term high-response inhibitor should be applied to cases
where the inhibitory activities have been >5 BU/mL at any
time.
Factor VIII Activity and Factor VIII Inhibitor give a
quantitative value for inhibitor activity in the
determination of treatment options and the Nijmegen gives
a more accurate value to low titer inhibitors which
impacts treatment options.
Unlike other tests which use human coagulation Factors IX
and X, the reagents used in this test contain bovine
Factors IX and X. In patients being treated with
Emicizumab (Hemlibra), the drug will interact with
activated Factor IX and factor X, which will result in
Factor X being activated in the absence of Factor VIII
activity. This could result in a false negative result,
as even in the presence of Factor VIII inhibitors
Emicizumab will cause the coagulation cascade to proceed.
Emicizumab does not interact with bovine factors
therefore there is no risk of Emicizumab interference
with this test.
