Transdermal vs oral estrogen and clots

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There are a number of studies that show transdermal estrogen does not cause increased storke, etc unlike oral estrogen,. Here are three references out of a dozen.

1. The main one is from the huge EPIC study in France of more than 100,000 women.

Arteriosclerosis, Thrombosis, and Vascular Biology. 1997;17:3071-3078

"Effects of Oral and Transdermal Estrogen/Progesterone Regimens on Blood Coagulation and Fibrinolysis in Postmenopausal Women

A Randomized Controlled Trial"

Pierre-Yves Scarabin et al.

.."The oral estrogen group was associated with a significant decrease in both mean tissue-type plasminogen (t-PA) concentration and plasminogen activator inhibitor (PAI-1) activity and a significant rise in global fibrinolytic capacity (GFC) compared with the two other groups. A transdermal estrogen regimen had no significant effect on PAI-1, t-PA, and GFC levels. There were no significant changes in mean values of fibrinogen, factor VII, von Willebrand factor, protein C, fibrin D-dimer, and plasminogen between and within the three groups. We conclude that oral estrogen/progesterone replacement therapy may result in coagulation activation and increased fibrinolytic potential, whereas opposed transdermal estrogen appears without any

substantial effects on hemostasis. Whereas these results may account for an increased risk of venous thromboembolism in users of oral postmenopausal estrogen, they emphasize the potential importance of the route of estrogen administration in prescribing hormone replacement therapy to postmenopausal women, especially to those at high risk of thrombotic disease."

2. Another - the ESTHER study involved thousands of women,

Circulation. 2005;112:3495-3500,

Cardiovascular Disease in Women:Hormone Therapy and Venous Thromboembolism Among

Postmenopausal Women; Impact of the Route of Estrogen Administration and Progestogens:

nne Canonico, et al

for the Estrogen and Thromboembolism Risk (ESTHER) Study Group

3. and another study

Arterioscler Thromb Vasc Biol. 2003 Sep 1;23(9):1671-6. Epub 2003 Jul 17.

Differential effects of oral and transdermal estrogen/progesterone regimens on sensitivity to activated protein C among postmenopausal women: a randomized trial.

Oger E, et al. SARAH Investigators.

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