On testosterone therapy, not only your testosterone changes, but often your estradiol too. Part of your testosterone converts into oestrogen, and that is normal, because oestrogen is not an enemy for men but a necessary hormone. Both a too-low and a too-high estradiol can cause symptoms, so the balance matters.
In practice I meet many men who want to push oestrogen down to the minimum. That is almost always a mistake.
Why do men need estradiol?
Estradiol is indispensable in men for your bones, your libido, your mood and your fat distribution. It arises because the enzyme aromatase converts part of your testosterone into oestrogen. Research showed that a deficiency of oestrogen in men mainly caused an increase in body fat and worsened sexual function (Finkelstein, 2013).
Oestrogen in men regulates erectile function, libido and spermatogenesis among other things (Schulster, 2016). Pushing it down too far therefore backfires.
What happens to estradiol on TRT?
Because TRT raises your testosterone, the estradiol that arises from it often rises too. In most men that is not a problem and belongs to a healthy balance. Symptoms mainly arise when the ratio tips far off, in either direction.
| Estradiol on TRT | Possible symptoms |
|---|---|
| Too high | Fluid retention, tender breasts, mood swings |
| In balance | Usually no symptoms |
| Too low | Joint complaints, low libido, low mood |
Estradiol also plays a role in your growth-hormone and bone health, which shows how broadly the hormone works (Russell, 2019).
Which blood values do you track?
On TRT you look at your testosterone and estradiol together, not separately. The combination shows whether your balance is right. Your doctor decides on that basis whether anything needs to change.
Relevant markers are estradiol, total testosterone, free testosterone and SHBG. Your haematocrit also belongs to the standard check.
How to keep your balance in view
TRT should always take place under medical supervision, and estradiol management is part of that. Measure your values at a fixed point in your dosing schedule, so your measurements are comparable. Never adjust medication yourself based on a single measurement.
To track your hormones, look at our TRT monitoring blood test. Also read stopping TRT and TRT and fertility.
My advice: do not chase the lowest possible estradiol. Aim with your doctor for balance and let your symptoms, not just your number, lead the conversation.
References
- Finkelstein JS, Lee H, Burnett-Bowie SM, et al. Gonadal steroids and body composition, strength, and sexual function in men. New England Journal of Medicine. 2013. PMID: 24024838.
- Schulster M, Bernie AM, Ramasamy R. The role of estradiol in male reproductive function. Asian Journal of Andrology. 2016. PMID: 26908066.
- Russell N, Grossmann M. Mechanisms in endocrinology: estradiol as a male hormone. European Journal of Endocrinology. 2019. PMID: 31096185.
Disclaimer
Every blood test result includes a professional assessment by a BIG-registered doctor. This article gives general information and is not a substitute for medical advice. A blood test is a tool to walk into the conversation with your GP better informed, not a diagnosis in itself. For treatment decisions, discuss your results with your GP.
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