Thrombomodulin-modified thrombin generation after in vivo recombinant factor VIII treatment in severe hemophilia A.
BACKGROUND
Thrombin generation has been shown to reflect coagulation potential and factor VIII (FVIII) levels in patients with hemophilia A. We hypothesize that thrombin generation in the presence of thrombomodulin reflects plasma FVIII levels better.


METHODS
Plasma FVIII levels were determined chromogenically and thrombin generation was measured with and without thrombomodulin in 12 patients with severe hemophilia A. Blood was sampled at baseline and 15 min, 1, 3, 6, 24 and 48 hours after recombinant FVIII administration.


RESULTS
FVIII administration restored the decreased baseline thrombin generation (reflected by endogenous thrombin potential, peak height, slope and time to peak). Lag time did not change. All thrombin generation parameters except time to peak returned to baseline within 48 hours, while plasma FVIII concentration was increased and time to peak shortened. Endogenous thrombin potential and peak height showed wide inter-individual variation, with strong intra-individual correlations. Addition of thrombomodulin to the assay shortened time to peak and decreased endogenous thrombin potential and peak height. The decrease in peak height was almost completely offset by FVIII administration. Multiple linear regression analysis revealed thrombomodulin-modified thrombin generation to be a moderately better predictor of plasma FVIII levels than thrombin generation in the absence of thrombomodulin (adjusted R(2) 0.79 vs. 0.71).


CONCLUSIONS
Addition of thrombomodulin has pronounced effects on all parameters of thrombin generation. This thrombomodulin-modified thrombin generation assay better reflects plasma FVIII levels than thrombin generation in the absence of thrombomodulin.
Dielis
Arne W J H
AW
Maastricht University, PO Box 616, UNS50/Box 8, 6200 Maastricht, The Netherlands. a.dielis@bioch.unimaas.nl
Balliël
Wolfgang M R
WM
van Oerle
René
R
Hermens
Wim T
WT
Spronk
Henri M H
HM
Ten Cate
Hugo
H
Hamulyák
Karly
K
D000293:Adolescent; D000328:Adult; D000368:Aged; D005169:Factor VIII / Q000627:therapeutic use*; D006467:Hemophilia A / Q000188:drug therapy* / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D011994:Recombinant Proteins / Q000627:therapeutic use; D013917:Thrombin / Q000378:metabolism*; D018180:Thrombomodulin / Q000378:metabolism*
D011994:Recombinant Proteins; D018180:Thrombomodulin; D005169:Factor VIII; D013917:Thrombin