Nowadays, many patients come to outpatient clinics and ask for sex hormone six tests. Some of them know that they should be checked but do not know when it is appropriate to do so, while some say that the doctor ordered them on the third day of menstruation. My personal experience is that there are several key time points for sex hormone examination, which have different meanings: First, the third day of menstruation is to check the basic endocrine. At this time, we are not looking at how low E2 is to determine whether estrogen is insufficient, which is originally low at this stage. Rather, E2 should be less than 50 pg/ml at this stage, if it is higher than this value, it indicates poor ovarian reserve and will often result in early menstruation, once in 21-25 days. At this time, FSH above 10 also indicates poor ovarian reserve. At this time, progesterone is definitely low. Some doctors only check the five items of basic endocrinology without checking progesterone for this reason. At this time, both LH and FSH should be in the range of 3-7 IU/L and the values should be close to the ideal. The endocrine check on the third day of menstruation (withdrawal bleeding) after progesterone use is definitely not allowed. It takes 20 days after progesterone use to completely eliminate its effects. Therefore, we can check the hormone level 20 days after stopping progesterone (or artificial cycle). If the patient is amenorrheic and without ovulation, if the progesterone is still low, the hormone level at this time is similar to the basic endocrine, and the E2 at this time is less than 50pg/ml, or even less than 20pg/ml before we can say that the patient has serious estrogen deficiency. The main purpose of this test is to check E2, LH and P. The main purpose is to see if there is a peak of LH before ovulation and to determine whether ovulation is approaching/or has occurred, and to use ultrasound follicle monitoring to diagnose the condition and guide the treatment (whether HCG injection is needed to promote ovulation and when is the best time to inject). The best time to check the luteal phase is one week before menstruation. If the basal body temperature is taken, it is usually checked when the basal body temperature rises 6-7 days. At this time, progesterone is theoretically at its highest level in the luteal phase, up to 40nmol/L or more. If the time calculation is accurate (about 7 days after the onset of menstruation) and the progesterone level is 15nmol/L or less at this time, the diagnosis of luteal insufficiency can be considered, and personally I think it is more meaningful to check at this time for those who have repeated miscarriages (the progesterone level is often low during pregnancy and miscarriage). If the progesterone level is <3nmol/L, it can be determined that there is no ovulation. In addition, if you come here specifically to check sex hormones, it is recommended that blood be drawn around 9:00-9:30 am, and that the blood be drawn at the entrance of the laboratory after sitting for 10 minutes in a resting state, so that the error fluctuation is smaller. However, clinical clinics are often not able to be bound, so they check as they come and if they find any abnormality, they will review the test next time as required.