Sex hormone-binding globulin as a marker for the thrombotic risk of hormonal contraceptives

Abstract

Background: It takes many years to get reliable values for the risk of venous thrombosis of hormonal contraceptive users from clinical data. Measuring activated protein C resistance (APC resistance) via thrombin generation is a validated test for determining the thrombogenicity of hormonal contraceptives. Sex hormone-binding globulin (SHBG) might serve as a marker for the risk of venous thrombosis and is an easy, rapid measurement which can be performed in routine laboratories. Objective To determine whether SHBG is a useful marker for the thrombotic risk of hormonal contraceptive by comparing plasma SHBG with APC sensitivity ratios (nAPCsr) and thrombosis risks reported in recent literature. Methods We conducted an observational study in 262 users of different contraceptives and measured nAPCsr and SHBG levels. Results: Users of contraceptives with a higher risk of venous thrombosis, i.e. combined hormonal contraceptives containing desogestrel, cyproterone acetate or drospirenone, and the transdermal patch, had higher SHBG levels than users of combined hormonal contraceptives containing levonorgestrel which carry a lower thrombosis risk. Users of the patch had the highest SHBG levels, with a mean difference of 246 nmol/L (95% CI 179 to 349) compared to levonorgestrel-containing combined hormonal contraceptives. SHBG levels were positively associated with both the nAPCsr and the risks of venous thrombosis reported in recent literature. Conclusion: SHBG is a useful marker to estimate the thrombotic safety of a preparation. © 2012 International Society on Thrombosis and Haemostasis.