Guide. An estrogen test measures the level of the most important estrogen hormones (estradiol, estriol, and estrone) in a blood or urine sample. 1  Estradiol is the most commonly measured type of estrogen for nonpregnant women.2  The amount of estradiol in a woman's blood varies throughout her menstrual cycle.n estrogen test measures the level of the most important estrogen hormones (estradiol, estriol, and estrone) in a blood or urine sample. 1  Estradiol is the most commonly measured type of estrogen for nonpregnant women. 2  Estriol levels usually are only measured during pregnancy. 3  Estrone may be measured in women who have gone through menopause to ...