title: Estrogen levels are higher across the menstrual cycle in African-American women compared with Caucasian women.
abstract: BACKGROUND
  Previous studies have suggested that estrogen levels may be higher in African-American women (AAW) compared with Caucasian women (CW), but none have systematically examined estrogen secretion across the menstrual cycle or in relation to other reproductive hormones.
  
  
  OBJECTIVE
  The objective of the study was to compare estradiol (E2), progesterone (P), gonadotropins, androstenedione (a'dione), inhibins, and SHBG levels between AAW and CW across the menstrual cycle.
  
  
  METHODS
  Daily blood samples were collected from regularly cycling AAW (n = 27) and CW (n = 27) for a full menstrual cycle, and serial ultrasounds were performed.
  
  
  METHODS
  Comparison of E2, P, LH, FSH, SHBG, inhibin A, inhibin B, and a'dione levels.
  
  
  RESULTS
  AAW and CW were of similar age (27.2 ± 0.6 yr, mean ± sem) and body mass index (22.7 ± 0.4 kg/m(2)). All subjects grew a single dominant follicle and had comparable cycle (25-35 d) and follicular phase (11-24 d) lengths. E2 levels were significantly higher in AAW compared with CW (P = 0.02) with the most pronounced differences in the late follicular phase (225.2 ± 14.4 vs. 191.5 ± 10.2 pg/ml; P = 0.02), midluteal phase (211.9 ± 22.2 vs.150.8 ± 9.9, P < 0.001), and late luteal phase (144.4 ± 13.2 vs. 103.5 ± 8.5, P = 0.01). Although LH, FSH, inhibins A and B, P, a'dione, and SHBG were not different between the two groups, the a'dione to E2 ratio was lower in AAW (P < 0.001).
  
  
  CONCLUSIONS
  Estradiol is higher in AAW compared with CW across the menstrual cycle. Higher estradiol in the face of similar androstenedione and FSH levels suggests enhanced aromatase activity in AAW. Such differences may contribute to racial disparities in bone mineral density, breast cancer, and uterine leiomyomas.
authors.affiliation: Reproductive Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: E E
authors.initials: EE
authors.lastname: Marsh
authors.forename: N D
authors.initials: ND
authors.lastname: Shaw
authors.forename: K M
authors.initials: KM
authors.lastname: Klingman
authors.forename: T O
authors.initials: TO
authors.lastname: Tiamfook-Morgan
authors.forename: M A
authors.initials: MA
authors.lastname: Yialamas
authors.forename: P M
authors.initials: PM
authors.lastname: Sluss
authors.forename: J E
authors.initials: JE
authors.lastname: Hall
mesh_terms: D000328:Adult; D000735:Androstenedione / Q000097:blood; D001141:Aromatase / Q000097:blood; D044383:Black People; D015992:Body Mass Index; D004958:Estradiol / Q000097:blood; D004967:Estrogens / Q000097:blood*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood; D008597:Menstrual Cycle / Q000097:blood*; D011374:Progesterone / Q000097:blood; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D044465:White People; D055815:Young Adult; D001741:Black or African American
chemical_list: D004967:Estrogens; D012738:Sex Hormone-Binding Globulin; D000735:Androstenedione; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D001141:Aromatase