title: FSH suppression does not affect bone turnover in eugonadal men.
abstract: BACKGROUND
  In vitro and animal studies have reported conflicting results regarding an independent role for FSH in the regulation of bone turnover.
  
  
  OBJECTIVE
  Our objective was to test the hypothesis that suppressing serum FSH while holding serum gonadal steroid levels stable in the eugonadal range will affect biochemical markers of bone metabolism in healthy men.
  
  
  METHODS
  Eugonadal men aged 20 to 50 years participated in this randomized controlled trial at a tertiary care academic teaching hospital.
  
  
  METHODS
  Participants received monthly GnRH analog injections to suppress FSH secretion plus daily topical testosterone gel in prespecified doses (intervention group). Controls received matching placebos (control group). Subjects in the intervention group were individually matched with subjects in the control group to ensure that the mean testosterone and estradiol levels (measured every 4 weeks during the 16-week study period) in the 2 groups were similar.
  
  
  METHODS
  Biochemical markers of bone resorption (serum N-terminal telopeptide and C-terminal telopeptide), bone formation (serum osteocalcin), and FSH were measured at baseline and after 16 weeks of treatment.
  
  
  RESULTS
  Serum FSH declined by 2% in the control group and by 60% in the intervention group (P < .0001 for the between-group difference). Despite the substantial suppression of serum FSH in the intervention group, serum N-terminal telopeptide, C-terminal telopeptide, and osteocalcin did not change in the intervention group, nor were any between-group differences observed.
  
  
  CONCLUSIONS
  When gonadal steroid levels are held constant, short-to midterm suppression of FSH does not affect bone turnover in men. FSH does not appear to be a significant regulator of bone metabolism in eugonadal men.
authors.affiliation: Endocrine Unit (A.V.U., J.S.F., B.Z.L.) and Biostatistics Center (H.L.), Massachusetts General Hospital, Boston, Massachusetts 02114.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Uihlein
authors.forename: Joel S
authors.initials: JS
authors.lastname: Finkelstein
authors.forename: Hang
authors.initials: H
authors.lastname: Lee
authors.forename: Benjamin Z
authors.initials: BZ
authors.lastname: Leder
mesh_terms: D000328:Adult; D016723:Bone Remodeling / Q000187:drug effects*; D024042:Collagen Type I / Q000097:blood; D004958:Estradiol / Q000097:blood; D005640:Follicle Stimulating Hormone / Q000037:antagonists & inhibitors* / Q000097:blood; D012739:Gonadal Steroid Hormones / Q000097:blood; D006066:Gonads / Q000502:physiology; D017273:Goserelin / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010455:Peptides / Q000097:blood; D013739:Testosterone / Q000097:blood; D055815:Young Adult
chemical_list: D024042:Collagen Type I; D012739:Gonadal Steroid Hormones; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D017273:Goserelin; D013739:Testosterone; D004958:Estradiol; D005640:Follicle Stimulating Hormone