title: Reduced levels of serum IGF-1 is related to the presence of osteoporotic fractures in male idiopathic osteoporosis.
abstract: BACKGROUND
  The pathophysiology of male idiopathic osteoporosis (MIO) remains unknown. The aim of this study was to evaluate the involvement of IGF-1 in MIO, and to explore the relationships between bone mineral density and serum levels of IGF-1 and sex hormones.
  
  
  METHODS
  Inclusion criteria were osteoporosis (T-score<-2.5 SD) and/or an osteoporotic fracture. The osteoporotic patients were included after an exhaustive work-up to exclude the principal causes of secondary osteoporosis. Serum levels of IGF-1, estradiol, testosterone, SHBG, markers of bone turnover, and bone mineral density were compared between 79 MIO and 26 healthy subjects.
  
  
  RESULTS
  A significant reduction in serum IGF-1 was found in MIO patients (p=0.0189). This remained significant after adjustment for body mass index (BMI). A negative correlation was found between SHBG and serum IGF-1 (r=-0.231, p=0.048). SHBG levels were higher in osteoporotic patients (p=0.001). The Free Testosterone Index (FTI, total testosterone/SHBG) (p=0.002) was also lower in MIO patients. After adjustment for FTI and BMI, a significant association was observed between IGF-1 level and the presence of an osteoporotic fracture, indicating an independent effect of IGF-1 level on fracture risk. The odds ratio (OR) for fracture for each SD decrease in IGF1 level was 1.8 [CI: 1.09-2.96] (p=0.021).
  
  
  CONCLUSIONS
  Our study indicates a decrease in serum IGF-1 levels in MIO. This could be either the cause or the consequence of a disturbance in sex hormone metabolism with increased SHBG serum levels.
authors.affiliation: Department of Rheumatology, University hospital of Lille, Lille 2, 59037 Lille cedex, France. julienpaccou@yahoo.fr
authors.forename: Julien
authors.initials: J
authors.lastname: Paccou
authors.forename: Juliette
authors.initials: J
authors.lastname: Dewailly
authors.forename: Bernard
authors.initials: B
authors.lastname: Cortet
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D015519:Bone Density; D003430:Cross-Sectional Studies; D004958:Estradiol / Q000097:blood; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000097:blood / Q000378:metabolism / Q000473:pathology*; D058866:Osteoporotic Fractures / Q000097:blood / Q000378:metabolism / Q000473:pathology*; D011446:Prospective Studies; D012737:Sex Factors; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D013739:Testosterone / Q000097:blood
chemical_list: D015415:Biomarkers; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D000469:Alkaline Phosphatase