Effects of vitamin D supplementation on fertility in patients with polycystic ovary syndrome

Sindrom policističnih jajnika (PCOS) smatra se najčešćim uzrokom anovulacijske neplodnosti. Unatoč godinama proučavanja, točna patofiziologija ovog sindroma još uvijek je velikim dijelom nepoznata. Čimbenici koji bi mogli imati značajnu ulogu u etiopatogenezi PCOS-a su genetski uvjetovana inzulinska rezistencija u perifernim tkivima uz istovremenu preosjetljivost jajnika na normalne razine inzulina, ovarijski hiperandrogenizam i poremećeno lučenje gonadotropina. U novije vrijeme u središte istraživanja etiopatogeneze PCOS-a stavlja se poremećeno stvaranje i funkcija AMH-a, kao i nedostatak vitamina D. Vitamin D ima fiziološku ulogu u reprodukciji muškaraca i žena. Kod žena on utječe na stvaranje progesterona u granuloza stanicama i na razvoj folikula te djeluje na razine AMH-a i povećanje osjetljivosti stanica na FSH. Prevalencija deficita vitamina D kod žena s PCOS-om iznosi od 67 do 85%, prema definiranoj razini nedostatka 25(OH)D3 od <20 ng/mL. Niske koncentracije vitamina D u organizmu mogu uzrokovati pogoršanje simptoma PCOS-a uključujući inzulinsku rezistenciju, ovulacijske i menstrualne nepravilnosti, neplodnost, hiperandrogenizam, pretilost i povećati rizik za razvoj kardiovaskularnih bolesti. Nadomjesna terapija vitaminom D bi mogla potencijalno imati važnu ulogu u poboljšanju plodnosti kod žena s PCOS-om jer vitamin D djeluje na inzulinsku rezistenciju i pretilost, smanjuje hiperandrogenizam i razine AMH-a u krvi, djeluje na razine PTH-a i ima učinak na molekule koje sudjeluju u reakcijama oksidativnog stresa na razini folikula. Daljnja istraživanja su potrebna kako bi se u potpunosti razumjelo djelovanje vitamina D na reproduktivni sustav i ustanovio učinak nadomjesne terapije vitaminom D na plodnost.Polycystic ovary syndrome (PCOS) is considered to be the most prevalent cause of anovulatory infetility. Despite years of extensive research, the exact pathophysiology of this syndrome remains unknown. Factors which could have a crucial role in the etiopathogenesis of PCOS, are periferal insulin resistance and at the same time ovarian hypersensitiviy on normal insulin serum level, ovarian hyperandrogenism, althered gonadotropine secretion and abnormalities at the adipose tissue level. The main focus of nowdays researche is based on altered secretion of AMH, and vitamin D defficinecy. Vitamin D plays a physiologic role in a reproduction both in men and women. It has an impact on progesterone production in human granulosa cells and ovarian follicular development, alters serum AMH levels and alters follicle-stimulating hormone sensitivity. Women with PCOS often have vitamin D deficiency defined by serum levels of 25(OH)D3 < 20 ng/mL with the prevalence of 67 to 85%. Low levels of vitamin D can lead to worsening of the symptoms in patients with PCOS, including insulin resistance, ovulatory dysfunction and irregular periods, infertility, hyperandrogenism, obesity, and also can increase the risk of cardiovascular diseases in these patients. Vitamin D supplementation could have a potentially important role in fertility in patients with PCOS because vitamin D appears to reduce insulin resistance and serum androgen levels. Furthermore, vitamin D is related to obesity, decreases serum levels of AMH, has an effect on serum levels of PTH and has an impact on molecules in oxidative stress reactions in the follicles. Further research is needed to determine the exact mechanism of action of vitamin D and to clarify the effect of vitamin D supplementation on fertility in patients with polycystic ovary syndrome