**2. Clinical presentation and clinical components in polycystic ovary syndrome (PCOS)**

#### **2.1. Menstrual irregularities in women with polycystic ovary syndrome (PCOS)**

This often occurs during the adolescent period at the menarche with menstrual irregularities mainly oligomenorrhea or less frequently amenorrhea. Over 70% of women with PCOS spontaneously reach menstrual regularity in the fourth decade of their life with metabolic dysfunction mainly in perimenopausal age [3]. The chronic state of anovulation present in these patients will produce amenorrhea and oligomenorrhea. An elevated pulse frequency for the luteinizing hormone (LH) has been documented [4]. The increased pulse frequency of the hypothalamic gonadotropin-releasing hormone (GnRH) promotes the transcription of the LH beta-subunit compared to the follicle-stimulating hormone (FSH) beta-subunit [5]. It is unclear whether this increase in pulse frequency is due to an inherent anomaly of the GnRH pulse generator or caused by low progesterone levels due to the chronic state of anovulation as progesterone slows down the GnRH pulse generator [6].

Most women with this syndrome exhibit oligomenorrhea with irregular vaginal bleeding episodes. The cause of such bleeding is not always referred to ovulation but may be caused by a sudden drop in plasma estrogen levels [7].

Increased ovarian androgen biosynthesis in the polycystic ovary syndrome results from abnormalities at all levels of the hypothalamic-pituitary-ovarian axis [8]. The etiopathogenesis of PCOs is multifactorial; all these factors act by creating a vicious circle that eventually leads to the syndrome. It is not yet clear at present what pathogenic event that triggers the chain reaction that leads to hyperandrogenism. The clinical manifestation of PCOs is the result of a series of alterations of physiological mechanisms, so there is not always a full expression of this syndrome. PCOs usually occur in puberty with menstrual disorders, hirsutism, and obesity. Alongside endocrine disorders, there are also metabolic disorders which, however, become more and more evident with the progress of time until they become predominant after menopause.
