Which estrogen delivery method is associated with a lower risk of venous thromboembolism and stroke?

Which estrogen delivery method is associated with a lower risk of venous thromboembolism and stroke?

• A. Oral estrogen
• B. Transdermal estrogen
• C. Vaginal estrogen
• D. Intramuscular estrogen

Answer: (B)

The key idea is how the estrogen is delivered affects how much the liver is involved in processing it. Oral estrogen goes through the portal circulation to the liver first, which stimulates the liver to increase production of several clotting factors and alter anticoagulant proteins. That tilt toward a pro-thrombotic state raises the risk of venous thromboembolism and, to some extent, stroke. Transdermal estrogen, on the other hand, enters the bloodstream through the skin and largely bypasses the liver’s first-pass metabolism, so it doesn’t significantly boost hepatic production of coagulation factors. Because of this, transdermal estrogen tends to have a lower impact on clotting risk and is associated with a lower risk of VTE and stroke compared with oral estrogen. Vaginal estrogen is mainly local with minimal systemic absorption, so systemic thrombotic risk is very low, but the standout reason the transdermal route is identified for reducing these risks is its bypass of hepatic first-pass metabolism.

The key idea is how the estrogen is delivered affects how much the liver is involved in processing it. Oral estrogen goes through the portal circulation to the liver first, which stimulates the liver to increase production of several clotting factors and alter anticoagulant proteins. That tilt toward a pro-thrombotic state raises the risk of venous thromboembolism and, to some extent, stroke. Transdermal estrogen, on the other hand, enters the bloodstream through the skin and largely bypasses the liver’s first-pass metabolism, so it doesn’t significantly boost hepatic production of coagulation factors. Because of this, transdermal estrogen tends to have a lower impact on clotting risk and is associated with a lower risk of VTE and stroke compared with oral estrogen. Vaginal estrogen is mainly local with minimal systemic absorption, so systemic thrombotic risk is very low, but the standout reason the transdermal route is identified for reducing these risks is its bypass of hepatic first-pass metabolism.