Factor XII (Hageman) Levels in Women with Recurrent Pregnancy Loss

Objective. To evaluate factor XII levels in women with recurrent pregnancy loss (RPL) in a tertiary referral hospital. Methods. Women who were referred to our hospital for two consecutive abortions or three abortions in between 2007 and 2013 were included in this retrospective observational study. Women were further grouped according to factor XII levels, as <60% and ≥60%. Results. Mean factor XII level was 109.1 ± 35.7% (range: 9–200). Ninety-three (7.4%) women had factor XII levels < 60%. Mean factor XII level was 44.8 ± 13.1, and levels ranged between 9 and 60 in this group. Only one woman had factor XII level < 10 %. Remaining 1164 (92.6%) women had factor XII levels ≥ 60%. Mean factor XII level was 114.3 ± 31.7, and levels ranged between 60.3 and 200 in this group, while 1015 (72.4%) women had factor XII levels within the normal range (60%–150% [100% = 30？μg/mL]). Conclusion. Decreased activity of F-XII was diagnosed in 7.4% of women with RPL. We concluded factor XII deficiency that might be a rare but significant factor for RPL, and should be evaluated in women who are investigated for recurrent pregnancy loss. 1. Introduction Coagulation and fibrinolysis balance plays an important role in sustaining a normal placental function. Thrombosis of spiral arteries and the intervillous space on the maternal side of the placenta can impair adequate placental perfusion. Impairments in uteroplacental circulation may cause fetal loss, fetal growth restriction, and/or preeclampsia. Coagulation factor XII (F-XII), which is also known as Hageman factor, is a plasma protein and a single-chain zymogen form of F-XIIa with no detectable enzymatic activity [1]. Factor XII is synthesized in the liver with a molecular weight of 80–90？kD and plasma concentrations are about 30？mg/mL [1]. Factor XII has a major role in the initiation of the intrinsic pathway of blood coagulation. It activates FXI and prekallikrein in the intrinsic pathway of the coagulation cascade. FXII deficiency is rare and may present as an autosomal recessive or acquired disorder. It is generally asymptomatic. On the contrary, excessive F-XII levels may result in venous thrombosis. Previously many studies suggested an association between factor XII (FXII) deficiency and autoantibodies to FXII and recurrent pregnancy losses [2–5]. In this study, we aimed to evaluate the prevalence of F-XII deficiency in women who were investigated for recurrent pregnancy loss (RPL) in a tertiary referral hospital. 2. Methods A cross-sectional study was conducted at Zekai Tahir Burak Women’s Health Care, Training and