Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

Hormone replacement therapy (HRT) increases the risk of venous thrombosis. We investigated whether this risk is affected by carriership of hereditary prothrombotic abnormalities. Therefore, we determined the two most common prothrombotic mutations, factor V Leiden and prothrombin 20210A in women who participated in a case-control study on venous thrombosis. Relative risks were expressed as odds ratios (OR) with 95% confidence intervals (CI95). Among 77 women aged 45-64 years with a first venous thrombosis, 51% were receiving HRT at the time of thrombosis, compared with 24% of control women (OR = 3.3, CI95 1.8-5.8). Among the patients, 23% had a prothrombotic defect, versus 7% among the control women (OR = 3.8, CI95 1.7-8.5). Women who had factor V Leiden and used HRT had a 15-fold increased risk (OR = 15.5, CI95 3.1-77), which exceeded the expected joint odds ratio of 6.1 (under an additive model). We conclude that the thrombotic risk of HRT may particularly affect women with prothrombotic mutations. Efforts to avoid HRT in women with increased risk of thrombosis are advisable.

Original publication




Journal article


Br J Haematol

Publication Date





851 - 854


Case-Control Studies, Estrogen Replacement Therapy, Factor V, Female, Heterozygote, Humans, Middle Aged, Mutation, Odds Ratio, Prothrombin, Risk, Venous Thrombosis