title: Menstrual irregularity and bone mass in premenopausal women: cross-sectional associations with testosterone and SHBG.
abstract: BACKGROUND
  There have been few studies examining the associations between menstrual irregularity, androgens and bone mass in population-based samples of premenopausal women. This study aimed to describe the associations between menstrual pattern, testosterone, sex hormone binding globulin (SHBG) and bone mass in a population-based sample of premenopausal women.
  
  
  METHODS
  Cross-sectional study (N = 382, mean age 31.5 years). Menstrual pattern was assessed by questionnaire, bone mass measured by quantitative ultrasound (QUS) and androgen status was assessed by levels of serum testosterone, SHBG and the free androgen index (FAI).
  
  
  RESULTS
  Women with irregular cycles (n = 41, 11%) had higher free androgen index (FAI, P = 0.01) and higher QUS measurements including speed of sound (SOS, 1%, P < 0.05), quantitative ultrasound index (QUI, 7%, p < 0.05), and broadband ultrasound attenuation (BUA, 7%, p = 0.10). These associations persisted after adjustment for age and body mass index (BMI). After further adjustment for hormonal factors (either testosterone, SHBG or FAI), the strength of the associations was moderately attenuated, however, women with irregular cycles still had a 6% increase in mean QUS. Total testosterone, FAI and SHBG were also associated with QUS measures (testosterone and FAI, r +0.11 to +0.21, all p < 0.05; SHBG r -0.14 to -0.16, all p < 0.05) and the associations remained significant after adjustment.
  
  
  CONCLUSIONS
  Irregular menstrual cycles were associated with higher bone mass in this population-based sample of premenopausal women suggesting menstrual disturbance should continue to be evaluated but may be less harmful for bone mass. The association between menstrual irregularity and bone mass was partially mediated by markers of androgen status especially free testosterone.
authors.affiliation: Menzies Research Institute, University of Tasmania, Hobart, Australia.
authors.forename: Shuying
authors.initials: S
authors.lastname: Wei
authors.forename: Graeme
authors.initials: G
authors.lastname: Jones
authors.forename: Russell
authors.initials: R
authors.lastname: Thomson
authors.forename: Petr
authors.initials: P
authors.lastname: Otahal
authors.forename: Terry
authors.initials: T
authors.lastname: Dwyer
authors.forename: Alison
authors.initials: A
authors.lastname: Venn
mesh_terms: D000328:Adult; D000728:Androgens / Q000097:blood; D015415:Biomarkers / Q000097:blood; D015519:Bone Density / Q000502:physiology*; D002111:Calcaneus / Q000000981:diagnostic imaging / Q000503:physiopathology; D003430:Cross-Sectional Studies; D005260:Female; D006306:Health Surveys; D006801:Humans; D008599:Menstruation Disturbances / Q000097:blood* / Q000503:physiopathology*; D017697:Premenopause / Q000097:blood* / Q000502:physiology*; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism*; D013739:Testosterone / Q000097:blood*; D014463:Ultrasonography
chemical_list: D000728:Androgens; D015415:Biomarkers; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone