title: Quantification of the relative contribution of estrogen to bone mineral density in men and women.
abstract: BACKGROUND
  The study quantified the relative contributions of estrogen (E2) and total testosterone (TT) to variation in bone mineral density in men and women.
  
  
  METHODS
  This was a cross-sectional study which involved 200 men and 415 women aged 18 to 89 years. BMD at the lumbar spine (LS) and femoral neck (FN) was measured by DXA. Serum levels of E2 and TT were measured by electrochemiluminescence immunoassays. The association between E2, TT, and BMD was analyzed by the multiple linear regression model, adjusting for age and BMI. The contribution of each hormone to the variation in BMD was quantified by the bootstrap method.
  
  
  RESULTS
  In women, higher serum levels of E2, but not TT, were significantly associated with greater BMD at the FN (P = 0.001) and LS (P < 0.0001). In men, higher serum levels of E2 were independently associated with greater FNBMD (P = 0.008) and LSBMD (P = 0.086). In the multiple linear regression model, age, body weight and E2 accounted for 50-55% variance in FNBMD, and 25% (in men) and 48% (in women) variance in LSBMD. Variation in E2 accounted for 2.5% (95% CI 0.4-7.8%) and 11.3% (95% CI 8.1-15.3%) variation in FNBMD in men and women, respectively. Moreover, E2 contributed 1.2% (95% CI 0.1-5.8%) and 11.7% (95% CI 8.5-15.9%) variation in LSBMD in men and women, respectively.
  
  
  CONCLUSIONS
  Estrogen is more important than testosterone in the determination of age-related bone mineral density men and women of Vietnamese background. However, the relative contributions of estrogen to bone mineral density in men are likely modest.
authors.affiliation: Department of Internal Medicine, Pham Ngoc Thach University of Medicine, Thanh Thai Street, District 10, Ho Chi Minh City, Vietnam. thuclanhopham@pnt.edu.vn.
authors.forename: Lan T
authors.initials: LT
authors.lastname: Ho-Pham
authors.forename: Nguyen D
authors.initials: ND
authors.lastname: Nguyen
authors.forename: Tuan V
authors.initials: TV
authors.lastname: Nguyen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People; D015519:Bone Density; D003430:Cross-Sectional Studies; D004958:Estradiol / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012727:Sex Characteristics; D013739:Testosterone / Q000097:blood*; D055815:Young Adult
chemical_list: D013739:Testosterone; D004958:Estradiol