IS HRT off limits if I’ve had a blood clot?

Menopause demystified: looking at the science behind common menopause questions

HRT is the first line treatment for management of menopausal symptoms [1].

But if you have had a blood clot in the past or have a condition that increases your risk of developing a clot, you may believe you are unable to take HRT, or have been told so by a healthcare professional.

Let’s take a look behind the science behind this question to get to the facts.

About blood clots

Blood clots can occur in a deep vein, usually in your leg, (known as deep vein thrombosis) and they can break off and travel to your lungs (pulmonary embolism) which can be very serious.

Certain conditions and treatments can increase your risk of getting a blood clot, such as some cancers or lupus. You are more likely to develop a clot if you are obese, a smoker or have had a clot in the past. There are some conditions (such a Factor V Leidin deficiency) which can run in families.

RELATED: Menopause and clots booklet

What does the evidence say about HRT and blood clots?

There is a small increased risk of a clot or stroke if you take estrogen in oral tablet form [2]. This is because when estrogen is taken as a tablet, it is metabolised in your liver, which produces clotting factors. This risk is only small but increases if you have a higher risk of clot.

However, estrogen delivered via a patch, gel or spray does not carry an increased risk of clot or stroke [3]. These types of HRT are known as transdermal HRT, because the estrogen goes straight into your bloodstream, so bypassing your liver.

Transdermal HRT is safe to take by women who have a high risk of clot or have had a clot in the past [4].

If you take estrogen in any form and still have your womb, you will need to take a progesterone to keep your womb lining thin and healthy. There are two types of progesterone – micronised progesterone and older, synthetic progestogens. While older types of progestogens are linked with an increased risk of clot, micronised progesterone does not have an increased risk of clot [5].

The safest way to take progesterone is micronised progesterone, known as Utrogestan.

Testosterone used as a gel or cream is not associated with a risk of clot when used in female doses.

What’s the bottom line?

Body identical HRT is still safe if you are at risk of developing or have had a blood clot in the past. Transdermal estrogen, micronised progesterone and testosterone as a gel or cream are the preferable options for you. Speak to a healthcare professional for an individualised conversation about HRT based on your medical history and menopause symptoms.

References

National Institute for Health and Care Excellence (2015), Menopause: diagnosis and management, www.nice.org.uk/guidance/ng23
Vinogradova, Y. et al. (2019), ‘Use of hormone replacement therapy and risk of venous thromboembolism: nested case-control studies using the QResearch and CPRD databases’, British Medical Journal, 364 k4810. doi:10.1136/bmj.k4810 Erratum in: BMJ. 2019 Jan 15;364:l162
Vinogradova Y., Coupland C., Hippisley-Cox J. (2019), ‘Use of hormone replacement therapy and risk of venous thromboembolism: nested case-control studies using the QResearch and CPRD databases’, British Medical Journal, 364:k4810. doi: 10.1136/bmj.k4810. Erratum in: BMJ. 2019 Jan 15;364:l162
Straczek C. et al (2005), ‘Estrogen and thromboembolism risk (ESTHER) study group. Prothrombotic mutations, hormone therapy, and venous thromboembolism among postmenopausal women: impact of the route of estrogen administration’, Circulation, 112(22):3495-500. doi: 10.1161/CIRCULATIONAHA.105.565556
Scarabin, P.Y. et al. (1997), ‘Effects of oral and transdermal estrogen/progesterone regimens on blood coagulation and fibrinolysis in postmenopausal women. A randomized controlled trial’, Arteriosclerosis, Thrombosis, and Vascular Biology, 17 (11), pp. 3071-8. doi:10.1161/01.atv.17.11.3071