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Estrone (E1)

A weaker estrogen made by the ovaries and by fat tissue. It is the main estrogen after menopause.

AI-verified against cited sources. Awaiting expert reviewLOINC 2258-2

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What it is

Estrone (E1) is one of the body's three main estrogens, along with estradiol and estriol. Before menopause, the ovaries make some, and the body also converts estrone and estradiol into each other. After menopause, the ovaries make very little estradiol, and most estrogen is estrone, made in fat and other tissues from hormones released by the adrenal glands. Men make small amounts too.

Why it matters

Estrone is a specialist test, usually ordered with estradiol. Clinicians may use it to look into early or late puberty, to check people on low-dose hormone therapy after menopause, to follow treatment with aromatase inhibitors, or to explore rare problems with how the body makes sex steroids. It can also be one piece of information when assessing fracture risk in postmenopausal women. One result is easiest to read alongside estradiol, FSH and your symptoms.

If it’s low

A low estrone is expected after menopause and early in the menstrual cycle. In younger women, a level that stays low can be linked to missed periods, low body weight, very heavy exercise or a problem with the ovaries or pituitary gland. Aromatase inhibitor medicines lower estrone on purpose. Low estrogen can affect bone health over time, so a level that stays low is worth discussing with a clinician.

Common causes

  • Menopause and the years after it
  • The early part of the menstrual cycle, just after a period
  • Aromatase inhibitor and other anti-estrogen medicines
  • Low body weight, not eating enough or very heavy exercise
  • A problem with the pituitary gland or hypothalamus, or ovaries that slow down early
  • Childhood before puberty

What can help

  • Ask your clinician whether estradiol, FSH and LH should be checked too
  • Ask whether your bone health needs a closer look if levels stay low for a long time
  • If you take hormone treatment, ask how your result fits your treatment plan

If it’s high

A high estrone is often explained by timing or by medicines. It rises in the second half of the menstrual cycle and in pregnancy, and estrogen medicines raise it on purpose. Extra body fat can raise it too, because fat tissue makes estrogen from other hormones. A high result that these don't explain is worth discussing with a clinician.

Common causes

  • The normal rise in the second half of the menstrual cycle
  • Pregnancy
  • Estrogen medicines, including oral estradiol, which the body partly converts to estrone
  • Higher body fat, which makes more estrogen from other hormones
  • Liver disease, because the liver helps clear estrogen from the blood
  • Fertility treatment that stimulates the ovaries
  • Rarely, a tumor of the ovary, adrenal gland or testis that makes estrogen

What can help

  • Share your medicines, supplements and cycle day with your clinician so the result can be read in context
  • Ask whether estradiol, FSH or other hormones should be checked too
  • Ask whether the test should be repeated on a specific day of your cycle

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

The usual range depends on sex. Choose women or men to see the one that applies.

What can affect your result

  • Menstrual cycle day: levels are lower in the first half of the cycle and higher in the second half
  • Menopause status and age
  • Pregnancy, when levels are far higher
  • Estrogen medicines, aromatase inhibitors and fertility drugs
  • Body fat and liver function
  • Test method and lab: mass spectrometry is preferred, and intervals differ between labs
  • The labs reviewed (Labcorp, Mayo, ARUP) measure estrone by mass spectrometry, which is more specific than immunoassay. Results from different methods should not be compared directly.
  • Estrogen medicines, hormone therapy, aromatase inhibitors and fertility drugs change estrone on purpose. Tell whoever reads your result what you take.
  • A separate estrone sulfate test exists, and its numbers are much higher (Labcorp reports it in ng/dL). Do not compare the two tests.

No set time of day is listed by the labs reviewed. If you still have periods, the cycle day matters, because estrone is lower early in the cycle and higher in the second half. Estrone follows what your ovaries, body fat and any estrogen medicine are doing, so it can change within days and swings through a menstrual cycle.

When to talk to a clinician

Talk with a clinician if you have missed several periods in a row and you aren't pregnant, if you have any vaginal bleeding after menopause, or if you are a man with new breast growth or tenderness. For children, talk with a pediatric clinician if puberty starts unusually early or seems very late.

Questions you could ask

  • Why was this test ordered, and how will the result change my care?
  • Should I use the same lab for repeat tests?
  • Could my medicines, supplements or body weight explain this?
  • Should we check estradiol or other hormones too?
  • Does my result fit my menopause status or cycle day?
  • Should my bone health be looked at if levels stay low?

Questions people ask

How is estrone different from estradiol?

Estradiol is the stronger estrogen and the main one before menopause. Estrone is weaker but becomes the main estrogen after menopause. The body converts each into the other, so clinicians often look at both.

Why do labs list such different estrone ranges?

Labs set their ranges using different people, methods and cycle-phase groupings. For example, adult men are listed as 10-50 pg/mL at Labcorp, 10-60 at Mayo and 9-36 at ARUP. Use the range printed on your own report.

Does body fat affect estrone?

It can. Fat tissue makes estrogen by converting other hormones, so people with more body fat can have higher estrone, especially after menopause. A clinician reads the number alongside your other results.

Show the science and sources

Units

  • 1 pg/mL = 1 pg/mL
  • 1 pg/mL = 3.698 pmol/L

Open the Estrone unit converter

For clinicians and researchers

Estrone (E1, MW 270.4) is a weaker estrogen than estradiol. The two are interconverted by 17-beta-hydroxysteroid dehydrogenase. Before menopause, estrone comes partly from the ovary and partly from conversion of estradiol. After menopause, most estrogen is estrone formed by aromatization of adrenal androgens such as androstenedione in peripheral tissues, mainly fat. Oral estradiol is partly converted to estrone on first pass through the gut and liver, which gives a high estrone-to-estradiol ratio with oral therapy. Mayo lists uses including puberty work-ups, disorders of sex steroid metabolism (aromatase and 17-alpha-hydroxylase deficiency), an adjunct in fracture risk assessment in postmenopausal women, and monitoring low-dose hormone therapy or antiestrogen therapy. Labcorp, Mayo and ARUP all use mass spectrometry. Adult intervals differ across the three: men 10-50 (Labcorp), 10-60 (Mayo) and 9-36 pg/mL (ARUP); postmenopausal women under 40 (Labcorp), 7-40 (Mayo) and 3-32 pg/mL (ARUP). Premenopausal values span 17-200 pg/mL at Mayo and are split by phase at Labcorp (follicular 30-100, luteal 90-160) and ARUP. Conversion: pg/mL x 3.704 = pmol/L (Mayo, MW 270).

LOINC 2258-2 (primary), 22663-9, 35208-8. Specimen: serum.

Sources

  1. Endocrinology Expected Values and S.I. Unit Conversion Tables, Labcorp (Endocrine Sciences specialty testing) (2021)
  2. Estrone (E1) (Mayo Clinic Laboratories test E1), UW Medicine Laboratory Test Guide, UW Medicine Laboratory Medicine and Pathology (reproducing Mayo Clinic Laboratories information)
  3. Estrone, by Mass Spectrometry (test 0093249), ARUP Laboratories
  4. Estrone (PubChem compound 5870), PubChem (National Library of Medicine)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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