The range and variation in serum estradiol concentration in perimenopausal and postmenopausal women treated with transdermal estradiol in a real-world setting: a cross-sectional study
What is this study about?
This 2025 study led by Dr. Sarah Glynne with co-authors including Dr. Louise Newson, one of my favorite menopause doctors, examined how much estradiol levels vary among perimenopausal and postmenopausal women using transdermal estradiol (patches, gels, sprays) in real-world clinical settings.
When was it conducted and how many women were included?
The cross-sectional study took place at a UK specialist menopause clinic, where 1,508 women had their serum estradiol levels tested while on treatment.
What did they find?
- The median estradiol concentration was 355 pmol/L (≈ 96 pg/mL), but levels ranged widely — from as low as 55 pmol/L (≈ 15 pg/mL) to over 2,000 pmol/L (≈ 544 pg/mL).
- Over 60% were on licensed doses, yet some still showed very low absorption, meaning their estrogen levels weren’t reaching therapeutic ranges.
- Younger women and those using gels showed more variability in absorption.
- This wide variation highlights that “one-size-fits-all” dosing doesn’t always work.
Why does this matter?
This study confirms what many women already experience: two women can use the same patch or gel and get totally different results. Crazy, right? Low estradiol may mean symptoms like hot flashes, brain fog, and sleep issues persist, while excessively high levels could bring side effects. It underscores the need for individualized care and, sometimes, lab testing to fine-tune HRT. I can’t tell you how many women I meet who have about 30% – 50% relief, but not shooting for 100%. Why not?
What am I doing about it?
I always encourage women in our community to test, not guess, but I also know testing in perimenopause can be tricky. Levels can fluctuate daily, even hourly, and lab results need to be read in context. A knowledgeable doctor knows how to interpret those results, look at the trends, and connect them with your symptoms.
I’ve covered this in a few of my podcast episodes where doctors weigh in with very different opinions on menopause testing. Some are for it, some against, but all offer valuable insights:
- Should You Test Hormones in Menopause?
- The Pitfalls of Hormone Testing
- Testing vs. Symptoms – Which Matters More?
These might help you better understand both sides of the debate.
Practical tips for women on HRT
- Know your symptoms. If hot flashes, brain fog, or joint pain persist, your dose or absorption may be off.
- Check your levels if needed. A simple blood test can show if you’re absorbing well, but don’t rely on numbers alone.
- Experiment with delivery methods. Some women do better on patches, others on gel, spray or even oral and injectables.
- Work with a knowledgeable practitioner. Someone who listens and adjusts based on you, not just the lab slip. Read this blog article to find a practitioner who can help you in your area.