Mojca Božič

D-dimer, other markers of haemostasis activation and soluble adhesion molecules in patients with different clinical probabilities of deep vein thrombosis

Two automated turbidimetric D-dimer assays (BC D-dimer Plus, Dade Behring, Marburg, Germany and Auto-Dimer, Biopool, Umeå, Sweden) were compared to two enzyme-linked immunosorbent assays (ELISAs) (Enzygnost D-dimer micro, Dade Behring and Asserachrome D-dimer, Diagnostica Stago, Asnières, France) and two rapid D-dimer assays (SimpliRed, Agen Biomedical, Brisbane, Australia and Minutex, Biopool) in out-patients with suspected deep vein thrombosis (DVT). In addition, the performance of prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complex (TAT), and soluble adhesion molecules VCAM-1 and P-selectin for DVT diagnosis was assessed. One hundred and thirty-five consecutive out-patients with suspected DVT of the lower limb were included, and in 52 (39%), DVT was confirmed by compression ultrasound. All D-dimer assays investigated reliably excluded DVT in those patients without DVT irrespective of their pre-test clinical probability of DVT. One D-dimer ELISA (Dade Behring) gave the highest area under the receiver operating characteristic (ROC) curve compared to other assays, and therefore, this was the most accurate assay in differentiating patients with from patients without DVT. The diagnostic performance of one automated turbidimetric assay (Auto Dimer, Biopool) was similar to ELISA and its convenience close to rapid latex agglutination assays. Most patients with a high pre-test clinical probability of DVT had positive D-dimer regardless of the presence or absence of DVT, which decreased the specificity of the tests and made D-dimer determination less useful for this group of patients. Because the diagnostic accuracy [sensitivity, specificity, negative (NPV) and positive predictive value (PPV)] of F1+2, TAT, VCAM-1 and P-selectin was inferior to D-dimer assay, these assays could not substitute or supplement D-dimer testing in diagnosis of DVT. Levels of VCAM-1 and P-selectin were increased in patients with DVT and should therefore be investigated further to clarify their role in DVT.

Factor V Leiden, prothrombin 20210G --> A, methylenetetrahydrofolate reductase 677C --> T and plasminogen activator inhibitor 4G/5G polymorphism in women with pregnancy-related venous thromboembolism.

OBJECTIVE To establish the prevalence of inherited and acquired risk factors for development of venous thromboembolism (VTE) in pregnancy and the puerperium. STUDY DESIGN In a retrospective study, 30 women with a history of objectively confirmed venous thromboembolism during pregnancy or the puerperium were studied. Fifty-six women with normal pregnancies were included as controls. Antithrombin, protein C, protein S, lupus anticoagulants, homocysteine, factor V Leiden mutation, prothrombin 20210G-->A polymorphism, methylenetetrahydrofolate reductase (MTHFR) 677C-->T polymorphism and the -675 (4G/5G) polymorphism in plasminogen activator inhibitor 1 gene were analysed. RESULTS At least one thrombophilic defect was observed in 16 (53.3%) cases and in 12 (21.4%) controls (P=0.003); factor V Leiden in 8 (26.7%) cases and 3 (5.7%) controls (P=0.009); prothrombin 20210G-->A polymorphism in 8 (26.7%) cases and 4 (7.5%) controls (P=0.021) and antithrombin deficiency in 4 (13.3%) cases and in 1 (1.8%) control (P=0.029). Other inherited and acquired risk factors were similarly distributed among cases and controls. CONCLUSION Women with pregnancy-related venous thromboembolism have an increased prevalence of inheritable thrombophilic defects predisposing them to an increased risk of thrombosis.

Markers of hemostatic system activation during treatment of deep vein thrombosis with subcutaneous unfractionated or low-molecular weight heparin

Prothrombin fragments (F1+2), thrombin-antithrombin complexes (TAT) and D-dimers, markers of hemostatic system activation, were measured in 59 consecutive patients with deep vein thrombosis (DVT). Patients were randomly treated either with subcutaneous unfractionated heparin (UH) administered in two to three subcutaneous doses adjusted to activated partial thromboplastin time (APTT) or with low-molecular weight heparin (LMWH) (dalteparin) administered in a fixed dose of 200 IU/kg body weight in one subcutaneous injection daily. Before treatment, F1+2, TAT and D-dimer were above the cut-off level in 27/59 (46%), 34/59 (58%) and all (100%) patients, respectively. Significant associations were observed between F1+2 and TAT (r=.66, P<.001), TAT and D-dimer (r=.36, P<.005) and F1+2 and D-dimer (r=.30, P<.050). On the third day of treatment, F1+2 and TAT significantly decreased to reference values in almost all patients (in 64/66 determinations of both F1+2 and TAT) and remained low on the seventh day of treatment. Compared to pretreatment values, a nonsignificant decrease of D-dimer was noted in both groups, but all values remained above the cut-off value. When markers of hemostatic system activation in the UH and LMWH groups were compared, no significant differences were observed. It was concluded that subcutaneous UH in an APTT-adjusted dose and subcutaneous LMWH in a once-daily weight-adjusted dose controlled these markers of hemostatic system activation in a similar manner.

Major and potential prothrombotic genotypes in patients with venous thrombosis and in healthy subjects from Slovenia.

The objective of our study was to investigate the prevalence of the polymorphisms factor V Leiden (FVL), prothrombin G20210A (PT G20210A), methylenetetrahydrofolate reductase C677T (MTHFR C677T), plasminogen activator inhibitor type 1 –675 4G/5G (PAI-1 4G/5G) and factor XII –4 C/T (FXII –4 C/T) in 295 Slovenian patients with venous thrombosis (VT) and 223 healthy controls in order to establish their contribution to the risk for VT. The major genetic risk factor was FVL, while PT G20210A, MTHFR 677 C/T, PAI-1 4G/5G and FXII –4 C/T polymorphisms were not. However, PT G20210A increased the risk of recurrent VT, MTHFR C677T increased the risk in older patients, while the FXII –4 T allele suggested a possible protective effect in younger patients. The risk of VT increased with increasing number of genetic defects.

Mild Hyperhomocysteinemia and Fibrinolytic Factors in Patients with History of Venous Thromboembolism

Mild hyperhomocysteinemia is recognized as a risk factor for venous thromboembolism (VTE), though its role in the thrombogenic processes is not understood. Its possible association with impaired fibrinolysis was investigated in 157 patients (61 women, 96 men) below the age of 60 years (43+/-11, mean+/-SD) with a history of objectively confirmed VTE. Patients had significantly higher fasting total plasma homocysteine (tHcy) levels than 138 apparently healthy subjects (8.0, 6.6-9.9 micromol/L vs. 7.2, 5.9-8.6 micromol/L, P=0. 001; median, range between first and third quartile). In 17 of 157 patients (12%) hyperhomocysteinemia (tHcy>11.4 micromol/L for women and tHcy>12.6 micromol/L for men) was established. The adjusted odds ratio as an estimate of relative risk for VTE was 2.3 (0.8-7.0; 95% confidence interval). When patients with hyperhomocysteinemia were compared to patients without hyperhomocysteinemia, no significant differences in t-PA (antigen 9.2+/-5.5 microg/L and 9.7+/-4.7 microg/L, respectively; activity 1.3+/-0.5 IU/mL and 1.3+/-0.7 IU/mL, respectively) and PAI-1 (antigen 19.3+/-17.5 microg/L and 22.6+/-20. 4 microg/L, respectively; activity 15.0+/-12.6 and 15.8+/-13.3 IU/mL, respectively) were observed. In conclusion, this study showed an association between mild hyperhomocysteinemia and VTE, but provided no evidence for an independent association between hyperhomocysteinemia and alterations in fibrinolytic proteins.

Hemostasis Activation in Thrombophilic Subjects With or Without a History of Venous Thrombosis

Thrombophilia is considered to increase the risk of venous thrombosis (VT) due to hemostasis activation. To determine the level of hemostasis activation in thrombophilic subjects with or without a history of VT, hemostasis activation markers prothrombin fragment 1 and 2 (F1+2), thrombin—antithrombin complex (TAT), and cross-linked fibrin degradation products (D-dimer) were measured in 94 subjects with (patients) and 101 subjects without a history of VT (controls). A total of 34.8% of patients and 14.8% of controls (P = .002) had at least 1 thrombophilic defect (protein C deficiency, activated protein C [APC] resistance, presence of lupus anticoagulants, or prothrombin G20210A polymorphism). The subjects were divided into 4 subgroups: patients with (TF+ patients) and without (TF− patients) thrombophilia, and controls with (TF+ controls) and without (TF− controls) thrombophilia. Hemostasis activation was comparable between all patients and controls (TAT: 2.1 vs 2.6 µg/L; F1+2: 1.0 vs 0.9 nmol/L; D-dimer: 36 vs 37 µg/L, respectively) and between TF+ and TF− patients. However, TF+ controls had a significantly higher prevalence of increased hemostasis activation markers compared with TF− controls (TAT > 4.4 µg/L, 38.4 vs 7.3%; F1+2 > 1.1 nmol/L, 53.8 vs 22.0%; D-dimer > 78 µg/L, 30.7 vs 8.8% of subjects, respectively; all P < .05). After stratification for thrombophilic defects, hemostasis activation was associated with APC resistance in controls and with protein C deficiency in patients. To conclude, thrombophilia was associated with hemostasis activation in controls. We assumed that, in patients, the differences in hemostasis activation between subjects with or without thrombophilia were blurred due to undetermined and unidentified thrombophilic defects.

Fibrinogen Polymorphisms Taq I, Hae III and Bcl I Are Not Associated with a Higher Risk of Deep Vein Thrombosis

High fibrinogen is recognised as a risk factor for atherosclerosis. It seems that high fibrinogen is also a risk factor for deep vein thrombosis (DVT). It has been shown that certain polymorphisms in fibrinogen genes can influence the fibrinogen level. In this study, fibrinogen levels and the frequency of the polymorphisms Taq I, Hae III and Bcl I were studied in 114 patients with DVT and 244 healthy subjects. In non-smokers, fibrinogen levels above 5 g/l were associated with an increased risk of DVT (odds ratio 3.3, 95% confidence interval 1.6–7.0). The frequencies of common alleles were similar in patients and healthy subjects for all polymorphisms. An association between fibrinogen levels and the polymorphisms Taq I, Hae III and Bcl I was found in healthy subjects, but not in the patients. It was concluded from these data that the polymorphisms Taq I, Hae III and Bcl I are not major risk factors for DVT.