High factor XI, recurrent pregnancy loss, enoxaparin

Activity of coagulation factor XI in patients with spontaneous miscarriage: the presence of risk alleles

The aim of this study was to compare the activity of coagulation factor XI (FXI) between patients with spontaneous miscarriage versus control group with no history of miscarriage and thrombosis, and then we evaluated the occurrence of risk alleles in the relation to miscarriage. FXI activity was determined using a coagulometer (Sysmex, CA 1500, Japan). Single nucleotide polymorphisms (SNPs) of F11 and CYP4V2 genes were evaluated. We examined 55 patients versus 31 control subjects. We found significantly higher activity of FXI (p = 0.04) in patients versus control subjects. The occurrence of two SNPs (rs2289252 and rs2036914) of the F11 gene and SNP (rs13146272) of CYP4V2 gene was not significantly different between both groups. Increased activity of FXI may be a potential risk factor for miscarriage. High activity of FXI diagnosed in women with history of miscarriage is not probably caused by the presence of studied SNPs.

Testosterone, Thrombophilia, and Thrombosis

We describe thrombosis, deep venous thrombosis (DVT) pulmonary embolism (PE; n = 9) and hip-knee osteonecrosis (n = 5) that developed after testosterone therapy (median 11 months) in 14 previously healthy patients (13 men and 1 woman; 13 Caucasian and 1 African American), with no antecedent thrombosis and previously undiagnosed thrombophilia–hypofibrinolysis. Of the 14 patients, 3 were found to be factor V Leiden heterozygotes, 3 had high factor VIII, 3 had plasminogen activator inhibitor 1 4G4G homozygosity, 2 had high factor XI, 2 had high homocysteine, 1 had low antithrombin III, 1 had the lupus anticoagulant, 1 had high anticardiolipin antibody Immunoglobulin G, and 1 had no clotting abnormalities. In 4 men with thrombophilia, DVT-PE recurred when testosterone was continued despite therapeutic international normalized ratio on warfarin. In 60 men on testosterone, 20 (33%) had high estradiol (E2 >42.6 pg/mL). When exogenous testosterone is aromatized to E2, and E2-induced thrombophilia is superimposed on thrombophilia–hypofibrinolysis, thrombosis occurs. The DVT-PE and osteonecrosis after starting testosterone are associated with previously undiagnosed thrombophilia–hypofibrinolysis. Thrombophilia should be ruled out before administration of exogenous testosterone.