Oestrone (Estrone, E1) Test
The oestrone (estrone, E1) test measures one of the three principal endogenous oestrogens and the predominant circulating oestrogen after the menopause, when it derives largely from peripheral aromatisation in adipose tissue. It is a secondary marker used chiefly in postmenopausal assessment and in monitoring oral oestrogen therapy, which raises it disproportionately.
1
Biomarkers
Blood (serum)
Sample
3–5 business days
Turnaround
No — however, collection timing relative to the menstrual cycle should be documented in premenopausal women
Fasting
What is the Oestrone test?
The Oestrone Test measures E1, one of the three principal endogenous oestrogens and the predominant circulating oestrogen after the menopause. It is ordered to characterise oestrogen status in contexts where oestradiol alone is insufficient — notably in postmenopausal assessment and in monitoring certain forms of oestrogen therapy. Within oestrogen assessment, oestradiol is the first-line and most clinically informative measure, while oestrone is a secondary marker with defined uses. After menopause, ovarian oestradiol production falls and oestrone — derived largely from peripheral aromatisation of androstenedione in adipose tissue — becomes the dominant oestrogen, so it reflects adiposity-driven oestrogen exposure. Oral oestrogen therapy raises oestrone disproportionately because of first-pass hepatic conversion, making oestrone useful when monitoring such regimens. Oestrone is also included in comprehensive oestrogen and hormone-metabolism panels in functional practice. Because it circulates at low concentrations, particularly in postmenopausal women and men, the assay method matters and mass spectrometry is preferred for accuracy.
What does the Oestrone test measure?
Oestrone is one of the three principal endogenous oestrogens, alongside oestradiol and oestriol. It is produced by the ovaries in premenopausal women and, importantly, by peripheral aromatisation of androstenedione in adipose tissue — a route that becomes the dominant source after menopause. Oestrone is interconvertible with oestradiol via 17-beta-hydroxysteroid dehydrogenase and is substantially less potent at the oestrogen receptor. It is the predominant circulating oestrogen after the menopause, when ovarian oestradiol production falls.
Oestrone is a secondary oestrogen measurement, used chiefly in specific contexts rather than as a first-line test. It is most relevant in postmenopausal assessment, where it becomes the predominant oestrogen and reflects peripheral aromatisation influenced by adiposity, and in monitoring oestrogen therapy, particularly oral preparations that raise oestrone disproportionately. Oestradiol remains the primary measure of oestrogen status in most clinical contexts, and oestrone is interpreted alongside it rather than instead of it.
Why is the Oestrone test ordered?
- Assessment of oestrogen status in postmenopausal women, where oestrone is the predominant circulating oestrogen
- Monitoring of oral oestrogen therapy, which raises oestrone disproportionately through first-pass hepatic conversion
- Evaluation of oestrogen exposure in the context of adiposity, where peripheral aromatisation drives oestrone production
- Investigation of gynaecomastia or feminisation in men as part of a broader oestrogen assessment alongside oestradiol
- Comprehensive oestrogen profiling within functional and integrative hormone assessment, interpreted with oestradiol
- Assessment of suspected oestrogen excess where the source and pathway of oestrogen production are being characterised
- Evaluation of oestrogen status where oestradiol results are discordant with the clinical picture and a fuller oestrogen profile is warranted
Sample collection and turnaround
Sample type
Blood (serum)
Fasting required
No — however, collection timing relative to the menstrual cycle should be documented in premenopausal women
Collection method
Venipuncture at patient service centre
Turnaround
3–5 business days
Collection notes
Measure alongside oestradiol for meaningful interpretation. Document cycle day, menopausal status, and any oestrogen therapy including its route (oral versus transdermal), as well as aromatase-inhibitor use. A mass-spectrometry assay is preferred for accuracy at the low concentrations seen in postmenopausal women and men.
Specimen requirements
Minimum 0.5 mL serum. Separate serum from cells per Access Medical Laboratories protocol. Specimen stable refrigerated; follow Access Medical Laboratories transport guidelines.
What can affect Oestrone results?
Oestrone circulates at low levels in postmenopausal women, men, and children, where immunoassays are unreliable and can cross-react with other steroids. LC-MS/MS provides the specificity needed and is preferred.
Adipose tissue aromatises androstenedione to oestrone, so greater adiposity raises oestrone, particularly after menopause when this becomes the dominant source of oestrogen.
Oral oestrogens undergo first-pass hepatic metabolism that converts a substantial proportion to oestrone, raising oestrone disproportionately relative to oestradiol. Transdermal routes have less of this effect, so route must be documented.
In premenopausal women oestrone varies across the cycle alongside oestradiol, so the cycle day must be documented for meaningful interpretation.
Aromatase inhibitors block the peripheral conversion of androgens to oestrogens, substantially lowering oestrone — an intended therapeutic effect that must be accounted for in interpretation.
Oestrone and oestradiol are interconverted enzymatically, so the two move together and oestrone is interpreted alongside oestradiol rather than as an independent measure of oestrogen activity.
What do Oestrone results mean?
Elevated
An elevated oestrone may reflect adiposity-driven peripheral aromatisation, oral oestrogen therapy, or, in premenopausal women, the normal cycle. In men or postmenopausal women, an unexplained elevation prompts consideration of increased aromatisation or an oestrogen-producing source, interpreted alongside oestradiol and the clinical context.
Normal
Interpretation depends on sex, cycle phase, and menopausal status. A value normal for one life stage may be inappropriate for another, and oestrone is interpreted alongside oestradiol rather than in isolation.
Reduced
A low oestrone is expected in postmenopausal women not on therapy and reflects reduced ovarian and peripheral oestrogen production. Aromatase inhibitor therapy also lowers it. Low oestrone with low oestradiol supports an overall hypo-oestrogenic state.
Note: Oestrone is a secondary oestrogen measure — oestradiol remains first-line in most clinical contexts. It circulates at low concentrations where immunoassays are unreliable, so mass spectrometry is preferred. It is strongly influenced by adiposity and by oral (versus transdermal) oestrogen therapy, and is interconvertible with oestradiol, so it must be interpreted alongside oestradiol, cycle timing, menopausal status, and hormone-therapy route.
Frequently asked questions
Oestradiol is the more potent oestrogen and the first-line measure of oestrogen status. Oestrone is less potent and is a secondary marker, becoming the predominant circulating oestrogen after menopause.
How to access the Oestrone test
The Oestrone reference page is free and open to all practitioners. Create a free practitioner account to see pricing, save tests to your list, and generate requisition forms. Verification takes 1–2 business days.
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Published: June 2, 2026
Last reviewed: June 2, 2026
- Rosner W, et al. Challenges to the measurement of oestradiol: an Endocrine Society position statement. J Clin Endocrinol Metab. (2013)
- Stuenkel CA, et al. Treatment of Symptoms of the Menopause: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. (2015)
- Simpson ER. Sources of oestrogen and their importance. J Steroid Biochem Mol Biol. (2003)
- Kuhl H. Pharmacology of oestrogens and progestogens: influence of different routes of administration. Climacteric. (2005)
This content is for licensed healthcare practitioners only and does not constitute medical advice. Clinical decisions should be based on the full clinical picture and not on any single test result.
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