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IGF-I and testosterone levels as predictors of bone mineral density in healthy, community-dwelling men


Dr. David A. Hanley, 3330 Hospital Drive, NW, Calgary, Alberta, Canada, T2N 4N1. Tel.: (403) 220-3037; Fax: (403) 270-0979; E-mail:


objective Age-related decline in IGF-I and gonadal hormones have been postulated to play an important role in the pathogenesis of age-related bone loss in men. In this cross-sectional study, the relation between serum IGF-I and gonadal hormones with bone mineral density (BMD) was examined in community-dwelling men.

design and subjects Serum IGF-I, testosterone and BMD were examined in 61 community-dwelling men over the age of 27, who were randomly selected from the Calgary cohort of 1000 subjects in the Canadian Multicentre Osteoporosis Study. In the present study, IGF-I, serum testosterone, SHBG, free androgen index (FAI), parathyroid hormone (PTH), 25-hydroxy-vitamin D [25(OH)D] and other markers of bone turnover were measured. BMD was measured at the spine and hip (HOLOGIC 4500). Simple linear regression was used to assess the linear relation between IGF-I, testosterone, BMD and other biochemical markers of bone metabolism and potential confounding variables and subsequent multivariate regression models were constructed separately for each BMD measurement to assess the importance of IGF-I and testosterone in the presence of potential confounding variables.

results Serum IGF-I, FAI and SHBG significantly decreased as a function of age, whereas serum levels of PTH increased. Only 25(OH)D, total testosterone and FAI were positively associated with serum IGF-I after adjusting for age and BMI. Multiple linear regression models revealed that IGF-I was a significant predictor of BMD at the total hip, femoral neck and femoral trochanter neck (P ≤ 0·001). In contrast, the FAI was a significant predictor of BMD at the lumbar spine and wards area (P ≤ 0·011), and SHBG was a significant predictor at the total hip and femoral trochanter (P ≤ 0·045).

conclusion These data support the hypothesis that the age-related decline in bone mass in men is associated with declining levels of IGF-I and testosterone.

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