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.