Thrombin Decrease in Thrombin Generation after Heparin Administration in a Homozygous Type II Heparin-Binding Site Antithrombin-Deficient Pregnant Woman

OBJECTIVES: There is a major problem in providing prophylactic treatment in antithrombin (AT)-deficient pregnant women with a homozygous mutation of the heparin-binding site and AT level of 17%. The aim of the study was to determine the effectiveness of heparin by monitoring changes in thrombin generation (TG) in vitro so that pregnant women are not exposed to stress in vivo. METHODS: We used the chromogenic method for determination of factor Xa (FXa) inhibition for enoxaparin, nadroparin, dalteparin, fondaparinux, and unfractionated heparin and the thrombin generation assay. RESULTS: We found that the degree of inhibition is very different when different heparins are compared. Nadroparin reduces TG, the most compared to low molecular weight heparins (LMWHs). CONCLUSION: Routine monitoring of anti-FXa activity should be supplemented with TG monitoring, where the effect of LMWH does not manifest itself as this could help in estimating thrombophilic risk during pregnancy.