Estradiol

Also written as: E2, Oestradiol

The main form of estrogen, which changes dramatically across the menstrual cycle and with menopause.

What it measures

The concentration of estradiol, the most active form of estrogen, in the blood. In people who menstruate the level swings widely across the cycle, so the result is only meaningful alongside the timing of the draw within the cycle.

Why a doctor orders it

Ordered to help evaluate irregular or absent periods, fertility questions, symptoms around menopause, and early or delayed puberty, and to monitor certain fertility treatments. It is usually interpreted together with FSH and LH rather than on its own.

What is generally associated with a higher result

Broadly associated with the normal mid-cycle peak, with pregnancy, with estrogen-containing medications, and with certain ovarian conditions. In men, raised values are broadly associated with increased conversion from testosterone, which can occur with higher body weight.

What is generally associated with a lower result

Broadly associated with menopause, reduced ovarian activity, low body weight or very intense exercise, and suppression by some hormonal contraceptives. Levels are also naturally low at certain points in the menstrual cycle.

Everyday things that move this number

Not every shift in a value reflects disease. These are ordinary factors known to affect this particular measurement:

The day of the menstrual cycle on which blood was drawn
Hormonal contraception, which can suppress or supply estrogen
Pregnancy and breastfeeding
Significant weight change or intense exercise training
Biotin supplements, which can interfere with some lab methods

Questions to take to your appointment

Does this result fit the day of my cycle when it was drawn?
Should FSH and LH be looked at alongside this?
Could my contraception be affecting this number?

Build a printable questionnaire with your own results →

Where to read more

MedlinePlus, from the US National Library of Medicine, publishes patient-facing pages on individual lab tests and is a reliable next stop: medlineplus.gov/lab-tests .

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