Laboratory test · Women’s health
Oestradiol (E2): when it is measured, which cycle day and what results mean
- Sample: venous blood
- Preparation: Cycle days 2.–5. or as directed by the doctor
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- Sample
- venous blood
- Preparation
- Cycle days 2.–5. or as directed by the doctor
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Oestradiol (E2) is the main female sex hormone in the oestrogen group. It is measured in blood when a doctor assesses ovarian function: for irregular or absent periods, fertility investigations and suspected early menopause, and in men for breast enlargement or sex hormone disorders.
Who is this test for
- women with irregular or absent periods,
- women undergoing fertility investigations,
- women younger than 45, particularly younger than 40 years, with suspected early menopause,
- men with breast enlargement (gynaecomastia) or signs of low testosterone,
- men undergoing infertility investigations, and sometimes for monitoring testosterone treatment.
What oestradiol is and what the result shows
Oestradiol, fully named 17-beta oestradiol, is the most active oestrogen in the body. In women it is produced by the maturing ovarian follicle, after ovulation by the corpus luteum, and during pregnancy by the placenta. It stimulates uterine lining growth and is important for bone strength. Men have small amounts, mostly formed through conversion of testosterone, particularly in fatty tissue.
The result shows how much oestradiol is in the blood at the time of collection. In women it changes daily, so a single value is meaningful only together with the cycle day.
For irregular or absent cycles, oestradiol alongside FSH, LH, prolactin and TSH shows whether the cause lies in the ovaries or the pituitary gland and hypothalamus. In fertility investigations it is measured alongside FSH early in the cycle: elevated oestradiol at this point may lower FSH into the normal range and conceal reduced ovarian reserve, so they are interpreted together.
Which cycle day to test oestradiol
The first day of menstruation is counted as day 1 of the cycle.
- Oestradiol is tested between days 2 and 5 of the cycle (usually day 2 or 3), or as directed by the doctor. This assesses baseline hormone status and fertility.
- To assess ovulation and the second half of the cycle, the doctor sometimes requests it later, alongside progesterone, which in a 28-day cycle is tested on days 21.–23.
- If you have no periods or very irregular cycles, agree the day with your doctor. After menopause the day does not matter.
Save with a panel
Test Oestradiol is also included in these panels.
Preparation and sample
The sample is venous blood. Fasting is unnecessary unless you are having tests that require it on the same day.
- When your blood is drawn, state the date of the first day of your last period.
- State whether you take hormonal contraception, hormone therapy or fertility medicines. Combined contraception suppresses ovarian oestradiol production, so the result does not then show actual ovarian function. Do not stop treatment yourself.
- If you take biotin (for example, hair and nail supplements), mention this when your blood is drawn. Also mention if you take fulvestrant, a breast cancer medicine, because it may falsely elevate the result.
How oestradiol results are interpreted
There is no single “normal” value. The reference interval depends on cycle phase, age, sex, pregnancy and laboratory method, and is printed on your report. Croatian reports express it in pmol/L, while international sources often use pg/mL (1 pg/mL ≈ 3,67 pmol/L).
| Period | Expected oestradiol level |
|---|---|
| Beginning of the cycle (early follicular phase) | Low to moderate |
| Before ovulation | Highest in the cycle |
| After ovulation (luteal phase) | After a brief fall it rises moderately again, then falls before menstruation |
| Pregnancy | Rises until the end of pregnancy, many times above cycle values |
| Perimenopause | Varies considerably |
| Postmenopause | Low and stable |
| Men | Low |
Pregnancy is not confirmed by oestradiol, but by the beta-hCG.
Your doctor interprets the result with the cycle day, symptoms and other hormones. A value outside the interval is not a diagnosis by itself, and the test is often repeated.
Elevated oestradiol in women
Elevated oestradiol most often has an expected explanation: sampling around or after ovulation, pregnancy, oestradiol therapy or ovarian stimulation. If elevated early in the cycle, it may indicate a functional cyst or reduced ovarian reserve, which the doctor assesses with FSH, AMH and ultrasound. Less common causes are liver disease, an overactive thyroid and, exceptionally, hormone-producing tumours.
Low oestradiol in women
Lower values are expected after menopause, during breastfeeding and with hormonal contraception. Otherwise, the doctor interprets oestradiol alongside FSH:
- low oestradiol and high FSH indicate reduced ovarian function (perimenopause, menopause, premature ovarian insufficiency);
- low oestradiol with low or normal FSH and LH indicates that the hypothalamus and pituitary gland are not stimulating the ovaries sufficiently, for example because of major weight loss, intensive exercise, stress, an eating disorder, elevated prolactin or pituitary disease.
In polycystic ovary syndrome (PCOS), oestradiol is usually not low and is not a diagnostic criterion.
Oestradiol in men
Elevated oestradiol most commonly accompanies excess weight, liver disease, testosterone therapy or anabolic steroids, and rarely a testicular tumour. It is interpreted alongside testosterone and SHBG, a protein that binds sex hormones.
How to arrange testing
Oestradiol is interpreted alongside other hormones, so fertility investigations often include it in the Fertility investigation panel (TSH, oestradiol, FSH, LH, prolactin, testosterone, AMH). Menopause panels are described in more detail on the page Menopause panels. You can attend for blood collection without an appointment or referral at one of our branches throughout Croatia (listed on the page Contactpage). Prices for all tests and panels are listed in the price list.
Frequently asked questions
Is E2 the same as oestradiol?
Yes. E2, beta oestradiol and 17-beta oestradiol are names for the same hormone. The designation distinguishes it from oestrone (E1), which predominates after menopause, and oestriol (E3), produced mainly during pregnancy.
Can I have oestradiol tested during menstruation?
Yes. Sampling between days 2 and 5 of the cycle usually falls during menstruation, and bleeding does not affect the result.
Can oestradiol confirm menopause?
Usually not. In otherwise healthy women aged 45 and over with typical symptoms, menopause is identified from symptoms without blood tests, as also recommended by the British NICE. During perimenopause, oestradiol varies considerably, so one result neither confirms nor rules out the transition. Hormone tests are more useful in younger women and for atypical symptoms.