Diagnostic significance of thrombin-antithrombin III complex (TAT) and D-dimer in patients with deep venous thrombosis.

Thrombin-antithrombin III (TAT) and D-dimer were measured in 50 patients suspected of deep venous thrombosis (DVT) to assess the usefulness of these indicators in the diagnosis of DVT. DVT was diagnosed by ultrasonography (compression method and Doppler imaging). In patients who were negative for DVT (Group A), TAT was 3.8 +/- 2.36 micrograms/L (mean +/- SD) and D-dimer was 0.7 +/- 0.69 micrograms/ml, whereas in patients diagnosed with DVT (Group B), TAT was 20.4 +/- 19.10 micrograms/L (p < 0.001) and D-dimer was 9.0 +/- 9.21 micrograms/ml (p < 0.001). Thus, Group B had significantly higher levels of both markers. Moreover, 19 of the 23 cases in Group B had acute DVT, with symptoms appearing within 2 weeks of onset. When the cutoff for a positive diagnosis of DVT was set at TAT of 7.0 micrograms/L or more and D-dimer of 3.0 micrograms/ml or more, sensitivity was 84%, specificity was 96%, and accuracy was 90%. Based on these results, we concluded that TAT and D-dimer are extremely useful in screening for acute DVT.