The level of estradiol in the body fluctuates significantly, and if a temporary high level of estradiol is detected, no special treatment is needed. If estradiol level is always high and menstruation does not occur, and the thickness of the endometrium continues to be thick or there are irregular echogenicity through ultrasonography, it may be caused by high estradiol level and continuous stimulation of the endometrium, and the continuous increase of estradiol may cause atypical hyperplasia of the endometrium or malignant hyperplasia of the endometrium, and endometrial cancer may occur. Therefore, persistently high estradiol level may increase the chance of endometrial cancer. In this case, progesterone can be applied to antagonize the proliferation, and if necessary, hysteroscopy should be performed to understand the proliferation status of the endometrium and to provide follow-up treatment.