title: Effects of HRT on serum levels of IGF-I in postmenopausal women.
abstract: OBJECTIVE
  It is thought that insulin-like growth factor-1 (IGF-I) stimulates bone formation. We aimed to determine the effects of oral and transdermal hormone replacement therapy (HRT) on serum IGF-I levels and to investigate the effects of basal IGF-I levels on the levels obtained at the end of the therapy.
  
  
  METHODS
  Sixty-six postmenopausal women were administered either oral (n=44) or transdermal (n=22) HRT for 6 months. Serum levels of IGF-I were determined before and after HRT in all subjects. Groups were divided into two subgroups according to the median value of serum IGF-I levels (basal IGF-I levels above or below the median value). The increase of IGF-I levels after HRT were calculated (%) for all women. Mean increases of subgroups were compared. Furthermore, study groups were divided into three subgroups according to the changing of IGF-I (increase>25%, between 25% increase and 25% decrease and decrease>25%). Mean basal IGF-I levels of these three subgroups were compared.
  
  
  RESULTS
  Mean serum levels of IGF-I before and after HRT were not significantly different in both oral and transdermal groups (P>0.05). Mean increases of IGF-I after HRT for the patients with low basal IGF-I levels, were 65% in oral and 77% in transdermal groups. However, mean increase of the patients with high basal IGF-I levels were -8 and -16% respectively. Moreover, mean level of basal IGF-I was significantly low in women who have more than a 25% increase after HRT (P<0.05).
  
  
  CONCLUSIONS
  HRT seems to significantly increase serum levels of IGF-I in postmenopausal women with low basal levels of IGF-I.
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine, Dokuz Eylul University, Kadin Hastaliklari ve Dogum ABD, 35340, Inciralti Izmir, Turkey.
authors.forename: C
authors.initials: C
authors.lastname: Posaci
authors.forename: S
authors.initials: S
authors.lastname: Altunyurt
authors.forename: H
authors.initials: H
authors.lastname: Islekel
authors.forename: A
authors.initials: A
authors.lastname: Onvural
mesh_terms: D000279:Administration, Cutaneous; D000284:Administration, Oral; D004958:Estradiol / Q000008:administration & dosage*; D015914:Estrogen Replacement Therapy / Q000379:methods; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008875:Middle Aged; D009640:Norethindrone / Q000008:administration & dosage*; D017698:Postmenopause / Q000187:drug effects* / Q000378:metabolism
chemical_list: D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D009640:Norethindrone