Estradiol is the most active natural estrogen, produced chiefly by the ovarian follicle in women and, in men, formed from testosterone by aromatase in fat and other tissues. The test reflects ovarian follicular activity across the menstrual cycle and, more broadly, estrogen exposure of bone, endometrium and the vascular system. In men it mainly reports how much androgen is being converted onward.
No readings for this marker yet.
In women, low values most often accompany menopause, suppressed ovarian function from weight loss or intense training, and pituitary causes; high values follow an active follicle, ovarian stimulation, or estrogen taken from outside. In men, raised estradiol most often accompanies excess body fat, liver disease, or testosterone therapy. Any single figure is read against the phase of the cycle and confirmed rather than acted on alone.
In a menstruating woman the result is uninterpretable without the cycle day, since it swings widely between the early follicular phase and the pre-ovulatory peak; oral contraceptives, hormone therapy and pregnancy shift it entirely. It is read together with LH and FSH, which show whether the ovary or the pituitary is setting the level, and with testosterone and SHBG when the balance between androgen and estrogen is the question. A doctor interprets the combination.
Reference ranges are general adult values and depend on lab, assay, age and sex. For orientation, not diagnosis — discuss results with your doctor.