Hormone replacement therapy (HRT) involves taking estrogen, progesterone, or both to supplement the body's natural hormones. While HRT provides benefits like relieving menopausal symptoms, it also carries risks like increased clotting. Clots can form deep in the veins of the legs (deep vein thrombosis) or in the lungs (pulmonary embolism). Though rare, clots are the main safety concern with HRT.
Several factors contribute to the increased clotting risk with HRT:
- Estrogen - Any estrogen HRT increases clotting factors in the blood. Oral estrogen (pills) is riskier than transdermal estrogen (patches). The dose also matters, with higher doses raising risk more.
- Progestins - Synthetic progestins have differing effects. Norethindrone and medroxyprogesterone acetate have more clotting risk. Natural progesterone likely has little or no effect.
- Route of administration - Oral HRT goes through the liver, raising clotting factors there. Transdermal estrogen avoids this "first pass" effect, so patches, gels, and sprays have lower clotting risks.
- Genetics - Some women have genetic clotting disorders and other risk factors that make HRT more dangerous for them. Testing can identify these women beforehand.
- Age - Older women are already at higher risk of clotting. The added HRT risk compounds this.
- Other medications - Some other drugs like tamoxifen also increase clotting. Combining HRT with these drugs heightens the risk.
The overall clotting risk is low for most healthy women on standard doses of HRT. For example, in women starting HRT around age 50, the chance of getting a clot over 5 years is:
- No HRT - 3 in 1000
- Oral estrogen progestin HRT - 7 in 1000
- Transdermal estrogen progestin HRT - 4 in 1000
So about 4 extra women per 1000 on transdermal HRT may get clots over 5 years. But HRT may prevent other health issues like fractures in this period. Doctors help women weigh these risks vs. benefits.
There are ways to reduce the clotting risk if using HRT:
- Use transdermal estrogen (patches, gel) instead of oral if possible
- Take the lowest effective estrogen dose
- Use natural progesterone instead of synthetic progestins
- Avoid HRT if under age 60, have other clotting risk factors, or take clot-inducing medications
- Maintain a healthy weight through diet and exercise
- Stop smoking and limit alcohol intake
- Move regularly - lack of movement raises clot risk
- Stay hydrated - dehydration thickens the blood
If HRT is needed for quality of life, these steps can help minimize the risks. Speak to your doctor about your clotting risk before starting HRT. Get medical care immediately if you develop clotting symptoms like leg swelling/pain or chest tightness. With some care, the benefits of HRT can often outweigh the small clotting risk.
If you're considering HRT, the caring physicians at Hormone Harmony Clinic can help you decide if it's right for you. Their individualized care and cutting-edge therapies help women improve their health during menopause and beyond. Contact Hormone Harmony Clinic today to schedule a consultation.
