Where do FSH and LH come from? If you analyze your brain, you will find a light at the bottom center of it, like a light that lights up the night – the pituitary gland, which is the most important endocrine gland in the body, divided into two parts, the anterior and posterior lobes, and FSH/LH is secreted by the anterior lobe, the pituitary gonadotropin cells. FSH and LH are like parents who nurture the healthy growth and development of follicles and promote their discharge from the ovaries. FSH is necessary to stimulate follicular development, especially to promote the growth and development of antral follicles and sinus follicles (understood as small follicles); to promote the synthesis and secretion of estradiol; to select a good follicle for reproduction; and to induce the production of LH receptors to prepare for the expulsion of the dominant follicle. LH, on the other hand, mainly stimulates androgen synthesis and provides substrate for estradiol (i.e. the basic substance); promotes further maturation of the oocyte and its discharge; and maintains luteal function. What are the normal values of FSH and LH? This may seem general. To put it another way, let’s talk about the changes in FSH and LH under physiological conditions. Specifically, their normal values are not fixed and vary during each phase of the menstrual cycle. For example, let’s take 28 days of a menstrual cycle as the standard, and describe them as follows: 1. The basal values of FSH and LH are 5-10 IU/L (measured on 2-3 days of menstruation), maintained at low levels and FSH>LH, with minimal fluctuations in FSH when ovarian function is normal. 2. 2-3 days before ovulation (i.e. day 11-12 of menstruation), the two rise rapidly, with LH rising significantly and can reach 3-8 times the basal value, sometimes up to 160 IU/L or higher, thus forming a peak (called LH peak), and the easy conception day is 2 days after the peak. In this way, the LH peak can also be used to guide infertility patients to have intercourse according to the LH peak to increase the chance of conception. In contrast, the change of FSH is only about 2 times of the basal value, rarely 30 IU/L. 3. FSH and LH drop rapidly after ovulation. What is the significance of FSH and LH when they are not normal values? The hypothalamus, pituitary gland and ovaries are the gonadal axis that constitute the female, and they regulate and influence each other. It is like the relationship between top leaders, cadres and employees. A few cases are cited as follows: 1, premature ovarian failure (POF): when FSH 40IU/L, LH elevated or 40IU/L, it can be considered high gonadotropin (Gn) amenorrhea, that is, ovarian failure, if it occurs before the age of 40, called premature ovarian failure. 2, low Gn amenorrhea: both FSH and LH 5IU/L is low Gn amenorrhea, suggesting hypothalamus or pituitary hypofunction. 3, poor ovarian reserve (DOR): FSH/LH 2 to 3.6 or FSH 12 IU/L, retested in the next cycle, 12 IU/L continuously (FSH can be in the normal range) suggests DOR, which is an early manifestation of poor ovarian function. elevated FSH/LH only reflects DOR, not the ability to conceive, and once ovulation occurs, the desired pregnancy rate can still be obtained. 4. polycystic ovary syndrome (PCOS): LH/FSH 2 to 3, can be used as the main indicator for the diagnosis of PCOS (basal LH level of 10IU/L is considered elevated, or LH maintains normal level while basal FSH is relatively low level, it forms an elevated LH to FSH ratio.) LH has the function of stimulating androgen synthesis, high LH leads to high androgen i.e. excessive androgen synthesis, and high High LH leads to hyperandrogenism, i.e. excessive androgen synthesis, and high androgen is an important causative factor for PCOS. 5, check 2 times basal FSH > 20IU/L, can be considered as premature ovarian failure insidious stage, suggesting possible amenorrhea after 1 year.