The effect of the levonorgestrel-releasing intrauterine system on the resistance to activated protein C (APC).
Exogenously administered estrogens and progestogens as during combined oral contraceptive use increase the risk of venous thrombosis. The thrombin generation-based APC resistance assay is a global coagulation test that enables quantification of the net prothrombotic effect of combined oral contraceptives and that predicts the risk of thrombosis. The thrombotic risk of the levonorgestrel-releasing intrauterine system is unknown. It was the objective of this study to evaluate the thrombotic risk by comparing the APC resistance before and after insertion of a levonorgestrel-releasing or a copper-containing intrauterine device. We measured normalized APC-sensitivity ratios (nAPCsr) before and three months after insertion of the levonorgestrel-intrauterine system in 56 women and the copper-intrauterine device in 18 women. In women without hormonal contraceptive use or a pregnancy in the three months before collection of the baseline samples, nAPCsr were lower three months after insertion of the levonorgestrel-intrauterine system than at baseline (difference -0.29; 95% CI -0.04 to -0.53) and hardly changed after insertion of the copper-intrauterine device (difference -0.11; 95% CI -1.03 to 0.82). In women who switched from a combined oral contraceptive to the levonorgestrel-system the difference was more pronounced (-1.48; 95% CI -0.85 to -2.11). In this study we observed that the levonorgestrel-intrauterine system decreases the resistance to APC which indicates that the levonorgestrel-intrauterine system does not have a prothrombotic effect.
Department of Gynaecology and Reproductive Medicine, Leiden University Medical Center, Leiden, The Netherlands. haam.vliet@worldonline.nl
Huib A A M
HA
van Vliet
Svetlana N
SN
Tchaikovski
Frits R
FR
Rosendaal
Jan
J
Rosing
Frans M
FM
Helmerhorst
D020016:Activated Protein C Resistance / Q000097:blood / Q000209:etiology* / Q000235:genetics; D000328:Adult; D015415:Biomarkers / Q000097:blood; D003277:Contraceptives, Oral, Combined / Q000009:adverse effects*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007435:Intrauterine Devices, Copper / Q000009:adverse effects*; D007436:Intrauterine Devices, Medicated / Q000009:adverse effects*; D016912:Levonorgestrel / Q000009:adverse effects*; D008875:Middle Aged; D010375:Pedigree; D018570:Risk Assessment; D012307:Risk Factors; D013917:Thrombin / Q000378:metabolism; D013997:Time Factors; D020246:Venous Thrombosis / Q000097:blood / Q000209:etiology* / Q000235:genetics; D055815:Young Adult
D015415:Biomarkers; D003277:Contraceptives, Oral, Combined; D016912:Levonorgestrel; D013917:Thrombin