The measurement of low levels of factor VIII or factor IX in hemophilia A and hemophilia B plasma by clot waveform analysis and thrombin generation assay.
BACKGROUND
Precise assessment of clotting function is essential for monitoring of hemostatic treatment for hemophilias A and B.


METHODS
Clot waveform analysis and thrombin generation assays were performed on factor (F) VIII- and FIX-deficient plasmas, which had been reconstituted with known amounts of recombinant FVIII (rFVIII) and affinity-purified FIX respectively. Clot waveforms were assessed qualitatively and quantitatively by measuring the parameters clotting time, maximum coagulation velocity (Min1), and maximum coagulation acceleration (Min2). The thrombin generation assay was also assessed qualitatively and measurements made of time to peak and peak height.


RESULTS
Overall results obtained with both assays showed good correlation for both clotting factors confirming that the changes in clotting waveform reflected changes in thrombin generation. Both assays demonstrated a predictable dose response to the addition of FVIII or IX. However, clot waveform analysis was more sensitive than the thrombin generation assay, particularly in detecting very low levels (0-0.1 IU dL(-1)) of both factors.


CONCLUSIONS
These data suggest that the application of clot waveform analysis to the routine management of the hemophiliacs could increase our understanding of the clinical significance of low levels of FVIII and FIX that cannot be measured by assays in current use. This may be particularly useful in the management of hemophiliacs with inhibitors or undergoing gene therapy.
Matsumoto
T
T
Department of Pediatrics, Nara Medical University, Nara, Japan.
Shima
M
M
Takeyama
M
M
Yoshida
K
K
Tanaka
I
I
Sakurai
Y
Y
Giles
A R
AR
Yoshioka
A
A
D001699:Biometry; D001780:Blood Coagulation Tests / Q000379:methods* / Q000706:statistics & numerical data; D005164:Factor IX / Q000008:administration & dosage / Q000032:analysis*; D005169:Factor VIII / Q000008:administration & dosage / Q000032:analysis*; D006467:Hemophilia A / Q000097:blood* / Q000188:drug therapy; D002836:Hemophilia B / Q000097:blood* / Q000188:drug therapy; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D010314:Partial Thromboplastin Time / Q000379:methods / Q000706:statistics & numerical data; D011994:Recombinant Proteins / Q000008:administration & dosage; D012680:Sensitivity and Specificity; D013918:Thrombin Time / Q000379:methods / Q000706:statistics & numerical data
D011994:Recombinant Proteins; D005169:Factor VIII; D005164:Factor IX