Serum anti-Müllerian hormone (AMH) levels are differentially modulated by both serum gonadotropins and not only by serum follicle stimulating hormone (FSH) levels.

It is generally accepted that serum AMH levels are thought to reflect the size of the ovarian follicle pool. Therefore, an inverse correlation between serum AMH and Follicle Stimulating Hormone (FSH) levels has been noted in older women with abnormal or exhausted follicular development, such as menopause, leading to the use of serum AMH as a marker of ovarian reserve. In clinical practice the use of serum AMH for the assessment of ovarian reserve has been expanding to women irrespective of age, such as women in early menopause or women undergoing ovarian stimulation for in vitro fertilization (IVF). To our knowledge, this opinion article aims to show that serum AMH levels are differentially modulated by both serum gonadotropins, depending on the degree of ovarian reserve. For instance, in conditions of increased LH and normal to low FSH such as young PCOS women with hyperandrogenemia, serum AMH levels are increased and tend to be associated to serum LH, while in conditions of increased FSH such as premature ovarian failure, serum AMH levels are decreased and tend to be associated to serum FSH. The evidence that supports the theory of a link between AMH and LH in PCOS comes from both in vitro and in vivo experiments. Serum AMH levels have been directly linked to serum LH levels in the most severe forms of PCOS. LH has also been shown in vitro to directly increase serum AMH levels in PCOS derived granulosa cells. Finally, hyperandrogenism, obesity, insulin resistance and OCs administration, indirectly affect serum AMH levels, by modulating serum LH. Concerning PCOS, the correlation between AMH and LH can be used in the future for the assessment of the severity of PCOS, of the amelioration of PCOS under OCs treatment, as well as of the efficacy of infertility treatment in clomiphene resistant PCOS women. Apart from PCOS, the clinical implications of this theoretical approach might become important in a variety of medical conditions. For instance, serum AMH levels might be used in the future as a marker of cysts formation in the ovaries as well as of ovarian endometriosis, or as a marker of ovarian response to treatment of ovarian cysts or ovarian endometriosis by oral contraceptives, etc. Additionally, in infertile women with hypothalamic amenorrhea, serum AMH levels might be used for the assessment of ovarian recovery under treatment.