fibrinopeptide-a and Antithrombin-III-Deficiency

Previous in vitro studies using spontaneously clotting whole blood revealed thrombin formation and high fibrinopeptide A (FPA) concentrations measured during incubation time. This occurred in spite of normal concentrations of thrombin antagonists present in the blood of the healthy subjects examined. However, there are several reports showing that in vivo increased thrombin-antithrombin III-complex (TAT) concentrations and relatively low FPA concentrations may occur e.g. in patients with (pre)thrombotic disorders. These in vivo findings indicate more effective thrombin inhibition by antithrombin III, with almost no fibrin formation. To find an explanation for the differences observed in vitro and in vivo, we extended the in vitro studies by measuring concentrations of prothrombin fragment 1 + 2 (F1 + 2), TAT and FPA at several time points until 30 min. Our goal was to test whether thrombin at least initially is neutralized by antithrombin III, resulting in a lack of fibrin formation, either in the absence or in the presence of heparin (0.2 and 0.5 U/ml whole blood, respectively). In the absence of heparin a simultaneous increase in the concentrations of F1 + 2, TAT and FPA was observed. Thrombin was only partially neutralized by antithrombin III and large amounts of fibrin were formed. The addition of heparin virtually suppressed thrombin formation since the F1 + 2 concentration remained low. Moreover, the small amounts of thrombin formed were neutralized by antithrombin III to a greater extent than in the absence of heparin.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adult; Antithrombin III; Antithrombin III Deficiency; Blood Coagulation; Female; Fibrinopeptide A; Heparin; Humans; Male; Peptide Fragments; Peptide Hydrolases; Prothrombin

Functional antithrombin III levels were measured by factor Xa inhibition in 63 members of a large family with type 2 antithrombin III deficiency and individuals were classified as antithrombin III deficient or non-deficient according to the results. F1 + 2 and TAT complexes were measured using an ELISA and FPA levels were measured by radioimmunoassay. Thirty subjects (48%) were classified as antithrombin III deficient and 33 (52%) as antithrombin III non-deficient. The mean level of F1 + 2 was significantly higher in the deficient adults (0.87 +/- 0.26) compared to both the non-deficient adults (0.70 +/- 0.21) (p = 0.03) and the deficient adults receiving warfarin (0.16 +/- 0.01) (p less than 0.001). The differences in the mean values of TAT complexes and FPA between deficient and non-deficient individuals were not statistically significant. These findings suggest that untreated antithrombin III deficient subjects generate more thrombin than their non-deficient family members and that warfarin inhibits this thrombin formation. In this cross-sectional study, it is not possible to correlate the levels of the surrogate makers with future clinical outcome.

Topics: Adolescent; Adult; Antithrombin III; Antithrombin III Deficiency; Biomarkers; Blood Coagulation; Child; Fibrinopeptide A; Humans; Peptide Fragments; Peptide Hydrolases; Prothrombin

We examined the changes of haemostatic molecular markers after antithrombin III (AT III) administration in a 22-year-old woman with congenital AT III deficiency in the third trimester of pregnancy who did not have thrombosis. Various markers including fibrinopeptide A (FPA), thrombin-antithrombin III complex (TAT), prothrombin fragment F1 + 2 (F1 + 2), plasmin-alpha 2antiplasmin, D-dimer, beta-thromboglobulin, and platelet factor 4 were measured before and just after 3,000 U of AT III concentrate, which was given three times per week from the 34 week of pregnancy until delivery. Just after AT III administration, F1 + 2 and FPA levels decreased on most occasions, while TAT sometimes increased. Plasma FPA levels were markedly decreased on all 8 occasions when the plasma FPA levels was above 2.0 ng/ml before AT III administration. Plasma FPA levels were always greater than or equal to 6.4 ng/ml before AT III administration on the 4 occasions when TAT increased to above 115%. The changes of plasma F1 + 2 levels were significantly correlated with the AT III level. These results suggest that prophylactic AT III administration in the third trimester immediately inactivates intravascular thrombin to form TAT and reduce the plasma FPA level. Thus, the transient TAT elevation following AT III administration may not only be due to extraction of thrombin from the fibrin clots of thrombi but also to intravascular thrombin which is not attached to thrombi. FPA is the best molecular marker for thrombin hyperactivity and it should be monitored in AT III-deficient pregnant women in the third trimester.

Topics: Adult; Antithrombin III; Antithrombin III Deficiency; Biomarkers; Blood Coagulation Factors; Female; Fibrinopeptide A; Humans; Incidence; Peptide Hydrolases; Pregnancy; Pregnancy Complications, Hematologic; Thrombosis

In 107 asymptomatic and untreated patients with inherited syndromes associated with thrombophilia (antithrombin III, protein C and protein S deficiencies), we compared in parallel two plasma peptides which reflect activation of the common coagulation pathway: the prothrombin fragment 1 + 2 (F1 + 2) and fibrinopeptide A (FPA). Both F1 + 2 and FPA were measured with simple, commercially available ELISA methods. High levels of F1 + 2 or FPA were found in about one fourth of the patients as a whole. When patients were divided according to the type of inherited thrombophilic syndrome, it appeared that F1 + 2 was more frequently elevated in protein C and protein S deficiencies than in antithrombin deficiency; and that, in general, it was no more frequently elevated than FPA. Although our data confirm the existence of a procoagulant imbalance in inherited thrombophilic syndromes due to defects of natural anticoagulant proteins, they do not confirm that such imbalance can be more frequently diagnosed by measuring F1 + 2 levels, particularly in patients with antithrombin deficiency.

Topics: Adolescent; Adult; Aged; Antithrombin III Deficiency; Biomarkers; Blood Proteins; Disease Susceptibility; Fibrinopeptide A; Glycoproteins; Humans; Middle Aged; Peptide Fragments; Protein C Deficiency; Protein S; Prothrombin; Syndrome; Thrombosis