Chemical structure of follicle stimulating hormone (FSH): a glycoprotein, consisting of two subunit peptide chains, a and b, bound by covalent bonds. It is a hormone secreted by basophilic cells of the anterior pituitary gland and is composed of glycoproteins. Its main action is to promote follicle maturation. Human follicle stimulating hormone promotes the proliferation and differentiation of cells in the granular layer of the follicle and the growth of the entire ovary. It acts on the testicular varicocele to promote sperm formation. FSH injections only increase the number of follicles and have no effect on follicle maturation. Follicle-releasing hormone secreted by the hypothalamus controls the secretion of follicle-stimulating hormone. During the menstrual cycle, the concentration of FSH in the blood and the amount of FSH excreted daily by urine vary with the cycle. After menopause, the amount of FSH excreted in blood and urine increases. a rapid rise in FSH values may be associated with ovarian failure. Clinical examination methods for increased follicle stimulating hormone (fsh): 1.Sex hormone level measurement Serum hormone level measurement shows increased FSH level and decreased estrogen level is the most important feature and diagnostic basis for POF patients, generally FSH>40U/L and estradiol<73.2. 2.Ultrasound examination Most POF patients have pelvic ultrasound showing shrinking ovaries and uterus and no follicles in ovaries. 3.Bone densitometry POF patients may show low bone mass and osteoporosis, which is caused by low peak bone mass and increased bone loss rate. 4, autoimmune index and endocrine index determination The clinical significance of this method is not yet certain. Anti-ovarian antibodies do not correlate with the severity of ovarian inflammation and do not predict whether and when ovarian failure will occur. 5. Ovarian biopsy If follicles are found to be present, the ovaries may lack FSH receptors and lack response to gonadotropins, a condition known as ovarian insensitivity syndrome. Because ovarian insensitivity syndrome is rare and the chance of pregnancy is rare, ovarian biopsy is generally not advocated. 6, Laparoscopy In premature ovarian failure, small, atrophic ovaries with inconspicuous follicles are seen, no initiating follicles are seen microscopically, and interstitial fibrosis of the ovaries.