The optimal time for estrogen testing is related to the patient’s status and gender. For female patients in general, it is recommended to check estrogen on the 2nd-3rd day of menstruation, while for male patients or amenorrheic female patients, estrogen testing can be performed at any time with no special timing requirements. The 2nd-5th day of menstruation is the early stage of follicular growth and the secretion of various hormones is low, so the basic secretion of the ovaries can be checked, especially on the 2nd-3rd day of menstruation. However, in special cases, if the patient’s condition is more critical, she should immediately go to the emergency room or endocrinology department for estrogen testing. In addition, both male and female patients are recommended to have their estrogen test in the morning on an empty stomach and to avoid strenuous exercise before having their blood drawn, as diet and exercise can affect the accuracy of the estrogen test and thus be detrimental to the doctor’s diagnosis of the disease.