Estrone (E1): The Estrogen That Rises With Age and Body Fat
Overview
Estrone, or E1, is one of the main estrogens in the body. Before menopause it plays a smaller supporting role compared to estradiol, but after menopause it often becomes the dominant estrogen because it is made in body fat and adrenal related tissues. In this glossary you will see what the estrone test measures, how it fits with Estradiol, how to think about higher and lower levels across life stages, what can nudge estrone up or down, how binding proteins like Sex Hormone-Binding Globulin shape its activity, and when it is worth walking your result through with a clinician.
What estrone is and why it matters
Estrone is a type of estrogen hormone. It is made in a few ways:
In ovaries before menopause, in smaller amounts
By converting adrenal androgens into estrogen in fat tissue
By conversion from other estrogens
Estrone is weaker than estradiol in terms of how strongly it activates estrogen receptors, but it still matters because it can convert into estradiol and contribute to the total estrogen environment in the body.
After menopause, ovaries produce far less estradiol, so fat tissue conversion becomes a bigger driver. That is why estrone often becomes the main circulating estrogen in postmenopausal adults.
What your estrone result can tell you
Your estrone value can help answer questions like:
What my baseline estrogen picture looks like for my age and life stage
Whether body fat conversion is a major contributor to my estrogen levels
If estrogen related symptoms or risks make sense in the context of my estrone and estradiol levels
Estrone is rarely interpreted alone. It is usually looked at together with estradiol and sometimes progesterone to understand overall estrogen balance. In postmenopausal adults, estrone can be a useful marker of how much estrogen is coming from peripheral conversion rather than the ovaries.
How to read high and low estrone
Estrone levels need context: cycle phase, age, menopausal status, and hormone therapy all matter.
When estrone is relatively high
Higher estrone can reflect:
Higher peripheral conversion in fat tissue
Certain hormone therapy patterns, especially oral estrogens that convert to estrone more strongly
Less commonly, ovarian or adrenal hormone producing conditions
In postmenopausal adults, higher estrone is often linked to higher body fat and insulin resistance. This does not automatically mean something is wrong, but it can matter for breast, uterine, and metabolic risk in some people. Symptoms that may travel with higher estrogen tone include breast tenderness, fluid retention, mood swings, or heavier bleeding if cycles are still present.
When estrone is relatively low
Lower estrone can reflect:
Low overall estrogen production, common in menopause or in very low body fat states
Reduced adrenal androgen conversion
Suppression from medications or energy deficiency
Low estrone after menopause is expected for many people, especially if estradiol is also low. If estrogen levels are low earlier in life and symptoms are present, clinicians often look for hypothalamic stress, ovarian function issues, or other endocrine drivers.
What can affect estrone levels
Estrone shifts with both hormone production and conversion. Common levers include:
Body fat and aromatase activity
Fat tissue converts adrenal androgens into estrone. Higher body fat often means higher estrone, especially after menopause. Lower body fat can mean lower estrone.Menopause and aging
As ovarian estradiol drops, estrone from peripheral conversion becomes more central. Fluctuations in perimenopause are common.Hormone therapy and birth control
Oral estrogen therapy often raises estrone more than estradiol because of liver conversion. Transdermal forms tend to raise estradiol more directly.Insulin and metabolic health
Insulin resistance can increase aromatase activity and shift estrogen conversion patterns. This is one reason estrone is sometimes higher in metabolic syndrome contexts.Adrenal androgen supply
Estrone depends partly on androgens produced by the adrenal glands. Changes in adrenal output can affect estrone.
Because these inputs overlap, estrone is best read next to estradiol, SHBG, symptoms, and life stage.
When to talk to a clinician about estrone
You should review estrone with a clinician when:
Sstrone is clearly high or low for your life stage and your symptoms do not match expectations
You are using estrogen therapy and want to confirm whether dosing and route are creating the intended balance
You have unexplained bleeding, breast changes, or strong estrogen related symptoms
You have higher metabolic risk markers and estrone is elevated postmenopause, since that combo can matter for long term risk planning
A clinician can place estrone alongside estradiol, progesterone, SHBG, and metabolic markers to decide whether this is a normal life stage pattern, a medication effect, a body composition driven shift, or something that needs deeper evaluation.
Estrone (E1) in one view
Estrone is a key estrogen that becomes especially important after menopause because it is made largely through conversion in body fat. Higher estrone often reflects higher conversion activity, body fat, or certain hormone therapies, while lower estrone usually aligns with low overall estrogen production. On its own it is just a snapshot, but together with estradiol, SHBG, symptoms, and life stage it helps clarify your real estrogen picture and what to fine tune with a clinician.
