Oestradiol (Estradiol, E2) Test
The oestradiol (estradiol, E2) test measures 17-beta-oestradiol, the most potent endogenous oestrogen, in serum. It is used to assess ovarian function, characterise the menstrual cycle, evaluate the menopausal transition alongside FSH, and monitor follicular response in assisted reproduction.
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Biomarkers
Blood (serum)
Sample
2–4 business days
Turnaround
No — however, collection timing relative to the menstrual cycle is essential and should be documented
Fasting
What is the Oestradiol test?
The Oestradiol Test measures 17-beta-oestradiol, the principal and most potent oestrogen, providing a direct index of ovarian oestrogen production and, more broadly, oestrogenic activity. Its dominant role is in assessing ovarian function and characterising the menstrual cycle, where it complements FSH, LH, and progesterone. Within the reproductive endocrine landscape, oestradiol is interpreted strictly in relation to cycle timing, sex, and life stage. It is used to investigate amenorrhoea and menstrual irregularity, to evaluate the menopausal transition alongside FSH, to assess pubertal development, and to monitor follicular response during ovulation induction and assisted reproduction. In males and in non-cycling contexts it helps investigate gynaecomastia, feminisation, or suspected oestrogen-secreting lesions. Because oestradiol assays differ in performance — particularly at the low concentrations seen in postmenopausal women, men, and children — the measurement method is clinically relevant, and LC-MS/MS may be preferred where high sensitivity is required.
What does the Oestradiol test measure?
Oestradiol is the most potent endogenous oestrogen, synthesised principally by ovarian granulosa cells from androgen precursors via aromatase, with smaller contributions from peripheral aromatisation in adipose tissue and, in males, the testes. It circulates largely bound to sex hormone-binding globulin and albumin, with a small free bioactive fraction. Levels fluctuate markedly across the menstrual cycle, peaking just before ovulation, and decline substantially after menopause. Oestradiol drives endometrial proliferation, follicular development, and secondary sexual characteristics.
Oestradiol measurement is central to assessing ovarian function, characterising the menstrual cycle, and investigating disorders of puberty, amenorrhoea, and the menopausal transition. It is used in fertility evaluation and assisted reproduction to monitor follicular development, and to investigate suspected oestrogen-secreting tumours or feminisation. As with progesterone, interpretation depends heavily on cycle timing, sex, and clinical context, and the assay method matters at low concentrations.
Why is the Oestradiol test ordered?
- Evaluation of amenorrhoea or oligomenorrhoea as part of a reproductive hormone profile with FSH, LH, and progesterone
- Assessment of the menopausal transition — low oestradiol with elevated FSH supports ovarian failure
- Monitoring of follicular development and ovarian response during ovulation induction and assisted reproductive technology cycles
- Investigation of suspected hypogonadism or delayed or precocious puberty, interpreted with gonadotrophins and age-appropriate ranges
- Evaluation of gynaecomastia or feminisation in males, where oestradiol may be raised relative to androgens
- Workup of suspected oestrogen-secreting ovarian or adrenal tumours where markedly elevated oestradiol is unexplained by cycle stage
- Monitoring of oestrogen therapy or aromatase-inhibitor treatment where oestradiol levels guide dosing
Sample collection and turnaround
Sample type
Blood (serum)
Fasting required
No — however, collection timing relative to the menstrual cycle is essential and should be documented
Collection method
Venipuncture at patient service centre
Turnaround
2–4 business days
Collection notes
Document the cycle day, menopausal status, and any oestrogen or aromatase-inhibitor therapy. Advise patients to withhold high-dose biotin supplementation for 48–72 hours prior to collection to avoid immunoassay interference. Where high sensitivity is required (postmenopausal women, men, children), an LC-MS/MS method may be preferred.
Specimen requirements
Minimum 0.5 mL serum. Separate serum from cells per Quest protocol. Specimen stable refrigerated; follow Quest transport guidelines.
What can affect Oestradiol results?
Oestradiol varies several-fold across the cycle, peaking just before ovulation. A specimen drawn without documented cycle timing is difficult to interpret; the cycle day must be recorded.
Supplemental oestrogens and contraceptive steroids alter measured oestradiol and may cross-react variably with the assay depending on the preparation and method. Treatment should be documented.
Immunoassays can be unreliable at the low oestradiol levels seen in postmenopausal women, men, and children, where LC-MS/MS offers better performance. Method should be considered when results seem discordant.
Aromatase inhibitors block peripheral and ovarian conversion of androgens to oestradiol, substantially lowering levels — an intended therapeutic effect that must be accounted for in interpretation.
Adipose tissue aromatises androgens to oestradiol, modestly raising levels, particularly in postmenopausal women and men, independent of ovarian output.
Biotin can interfere with streptavidin-biotin immunoassay platforms, producing falsely altered oestradiol. Patients should withhold high-dose biotin for 48–72 hours before collection.
What do Oestradiol results mean?
Elevated
Elevated oestradiol may reflect the pre-ovulatory peak, pregnancy, ovarian stimulation during assisted reproduction, exogenous oestrogen, or, where unexplained by these, an oestrogen-secreting ovarian or adrenal tumour. Context and cycle timing are essential before attributing an elevation to pathology.
Normal
Interpretation depends on cycle phase, sex, and life stage. A value normal for the follicular phase may be inappropriate for mid-cycle, and a premenopausal-range result in a postmenopausal woman may indicate an exogenous or pathological oestrogen source.
Reduced
Low oestradiol with elevated FSH and LH indicates primary ovarian failure or menopause. Low oestradiol with low or normal gonadotrophins suggests hypogonadotrophic hypogonadism of hypothalamic or pituitary origin and warrants further pituitary assessment.
Note: Oestradiol is uninterpretable without cycle, sex, and age context. Immunoassays are less reliable at low concentrations, so discordant low results may require an LC-MS/MS method. Exogenous oestrogens, aromatase inhibitors, and biotin can all distort results, and the marker is best read alongside FSH, LH, and progesterone.
Frequently asked questions
It measures 17-beta-oestradiol, the principal oestrogen, providing a direct index of ovarian oestrogen production. It is central to assessing ovarian function, the menstrual cycle, the menopausal transition, and fertility.
How to access the Oestradiol test
The Oestradiol 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
- Practice Committee of the American Society for Reproductive Medicine. Diagnostic evaluation of the infertile female: a committee opinion. Fertil Steril. (2015)
- Rosner W, et al. Challenges to the measurement of estradiol: 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)
- Santoro N, Randolph JF. Reproductive hormones and the menopause transition. Obstet Gynecol Clin North Am. (2011)
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.