title: Association between sex steroids, ovarian reserve, and vitamin D levels in healthy nonobese women.
abstract: BACKGROUND
  Vitamin D maintains calcium and phosphorous homeostasis and promotes bone mineralization; however, its nonskeletal functions are increasingly being recognized. Recent evidence supports a role for vitamin D in reproductive potential, but few studies have investigated the potential effects of vitamin D on reproductive hormone biosynthesis and ovarian reserve.
  
  
  OBJECTIVE
  The aim of this study was to determine the relationships between the serum level of vitamin D, reproductive hormone levels, and ovarian reserve in healthy nonobese women.
  
  
  METHODS
  This was a cross-sectional study.
  
  
  METHODS
  The study was performed at the Fertility Center at CHA Medical Center.
  
  
  METHODS
  Seventy-three healthy women volunteers participated in this study. The participants were nonobese parous women with regular menstrual cycles and no history of infertility.
  
  
  METHODS
  We determined serum levels of vitamin D, steroid hormones, SHBG, ovarian reserve markers, homeostatic model assessment of insulin resistance index, and lipid profiles.
  
  
  RESULTS
  In linear regression analysis adjusting for age, body mass index, homeostatic model assessment of insulin resistance, and lipid profile, serum vitamin D level positively correlated with total T (P < .001) and free androgen index (P < .001) but did not correlate with dehydroepiandrosterone sulfate or other steroid hormones. The spline regression-suggested relationship between 25-hydroxyvitamin D and total T was most pronounced at a 25-hydroxyvitamin D concentration greater than 13 ng/mL (β-coefficient 2.374, 95% confidence interval 1.435-3.313). The serum vitamin D level was not associated with the levels of ovarian reserve markers.
  
  
  CONCLUSIONS
  Our study revealed a positive correlation between serum vitamin D level and T level in healthy nonobese women, suggesting that vitamin D may increase fertility through the modulation of androgen activity. The possible causality of the relationship between vitamin D and T deserves further investigation.
authors.affiliation: Fertility Center of CHA Gangnam Medical Center, Department of Obstetrics and Gynecology, CHA University, Seoul, Republic of Korea.
authors.forename: Eun Mi
authors.initials: EM
authors.lastname: Chang
authors.forename: You Shin
authors.initials: YS
authors.lastname: Kim
authors.forename: Hyung Jae
authors.initials: HJ
authors.lastname: Won
authors.forename: Tae Ki
authors.initials: TK
authors.lastname: Yoon
authors.forename: Woo Sik
authors.initials: WS
authors.lastname: Lee
mesh_terms: D000328:Adult; D015992:Body Mass Index; D002452:Cell Count; D003430:Cross-Sectional Studies; D019314:Dehydroepiandrosterone Sulfate / Q000097:blood; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006262:Health; D006801:Humans; D056865:Ideal Body Weight; D009865:Oocytes / Q000166:cytology* / Q000000981:diagnostic imaging; D010053:Ovary / Q000166:cytology* / Q000000981:diagnostic imaging; D013739:Testosterone / Q000097:blood; D014463:Ultrasonography; D014807:Vitamin D / Q000097:blood*
chemical_list: D012739:Gonadal Steroid Hormones; D014807:Vitamin D; D013739:Testosterone; D019314:Dehydroepiandrosterone Sulfate