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Open Access

Prothrombin fragment F1+2 in patients with antiphospholipid antibodies

  • A Ambrozic1,
  • B Bozic1,
  • S Cucnik1,
  • T Kveder1 and
  • B Rozman1
Arthritis Res Ther20046(Suppl 1):3

Received: 16 January 2004

Published: 24 February 2004


Public HealthPlasma LevelPositive ResultConnective TissueElevated Level


Studies of specific markers for in vivo activation of coagulation in patients with antiphospholipid antibodies (aPL) are very rare. Increased levels of prothrombin fragment F1+2 (F1+2) in patients with APS were reported.


Our aim was to ascertain the relationship of F1+2 plasma levels with positive anticardiolipin (aCL) and anti-β2-glycoprotein I (anti-β2-GPI), and to evaluate the effect of treatment on F1+2 values in patients with APS.


A total of 205 samples from 177 patients with suspected or confirmed connective tissue disease without APS, and 15 samples from nine patients with APS receiving anticoagulant (n = 8) or antiplatelet (n = 1) therapy were tested for plasma F1+2 values (Enzygnost F1+2 micro, Behring, Germany), aCL (IgG, IgM) and anti-β2-GPI (IgG, IgM, IgA), all using in-house ELISAs.


Elevated values of F1+2 were statistically significantly associated with medium/high positive results for at least one isotype of aCL (P = 0.027), anti-β2-GPI (P = 0.019) and aCL and/or anti-β2-GPI (P = 0.014; Table 1). Furthermore, the mean level of F1+2 was significantly higher in patients with medium/high aCL or anti-β2-GPI than in those with negative/low positive aCL and anti-β2-GPI (P = 0.035). In all 15 plasma samples from APS patients, normal levels of F1+2 were measured during treatment.
Table 1

Association of F1+2 with aCL and/or β 2-GPI


Normal F1+2

Elevated F1+2


aCL and β2-GPI negative/low positive

128 (81%)

31 (19%)


aCL and/or β2-GPI medium/high positive

29 (63%)

17 (37%)



Our study showed a significant association of aCL and anti-β2-GPI with elevated levels of F1+2 in patients without APS not receiving anticoagulant or antiaggregation therapy. aPL are believed to be among the important causes of hypercoagulable state in those patients. Furthermore, plasma values of F1+2 could be a very useful indicator of successful treatment in APS patients.

Authors’ Affiliations

Department of Rheumatology, University Medical Centre, Ljubljana, Slovenia


© The Author(s) 2004