Secondary amenorrhea is a condition in which regular menstruation has been established in the past and the duration of the current menopause is greater than or equal to 6 months or at least equal to the duration of the previous 3 cycles. Amenorrhea is a clinical manifestation of a complex pathophysiological disorder with many causes: such as problems at various levels of the hypothalamus, pituitary gland, ovaries and uterus, and in some cases, genetic and chromosomal problems that may lead to amenorrhea. Therefore, in order to find the cause of amenorrhea and facilitate targeted treatment, certain tests, which are crucial for amenorrheic patients, usually include: First, a medical history: the patient needs to provide the doctor with her main symptoms such as breast overflow and hot flashes, excessive sweating, insomnia, emotional problems; frequency and quality of sexual life, the presence of weight loss, strenuous exercise, geographical changes, etc. Gynecological examination: There is a receiving doctor to check whether the secondary sexual characteristics (breasts, pubic hair and axillary hair) are normal, whether there is hairiness, acne and the condition of reproductive organs, and usually an ultrasound is also needed to further understand the condition of the endometrium. Gynecological ultrasound should be noted: for patients who have sex, transvaginal ultrasound or transabdominal ultrasound can be chosen; for those who do not have sex, transabdominal ultrasound is usually chosen (requires holding urine and filling the bladder). Blood levels of relevant hormones: FSH (follicle stimulating hormone), LH (luteinizing hormone), E2 (estradiol), PRL (prolactin), T (androgen) are tested. To rule out amenorrhea due to thyroid dysfunction, a TSH (thyroid stimulating hormone) test is sometimes required. In patients who are sexually active, blood or urine hCG (chorionic gonadotropin) is tested first to rule out pregnancy. The test should be performed after 1-3 months of discontinuation of various hormones or hormone-containing medications; blood should be drawn on an empty stomach before 11:00 am. The night before the blood draw, eat a low-fat diet, avoid sexual intercourse, maintain emotional stability, and get enough sleep. (4) You need to sit quietly in front of the laboratory for 15-30 minutes before the blood draw.