Context: The changes in bone mineral density (BMD; grams per square centimeter), a well-known predictor of future fracture risk, are not well investigated in young men.
Objective: The objective of the study was to investigate the changes in BMD in men between 17 and 26 yr of age.
Design: This was a longitudinal study.
Participants: Participants included 107 healthy males with a mean age of 17 yr at baseline. BMD was also measured in 81 of their fathers at a mean age of 50 yr.
Main outcome measures: BMD of the total body, proximal femur, and lumbar spine was measured at baseline and after mean periods of 27, 66, and 92 months in the young cohort.
Results: BMD of the total body and lumbar spine initially increased to reach a plateau during the study period. At the proximal femur, peak values were obtained at 19 yr of age, followed by significant losses of almost 0.02 g/cm(2) per year (P < 0.001). At this site, the fathers' BMD indicated a further loss of about 0.0085 g/cm(2) per year up to the age of 50 yr. The BMD development at all sites was positively associated with physical activity (P < 0.05). However, changes in physical activity, weight, and height did not explain the local BMD loss seen at the proximal femur.
Conclusion: Early losses of BMD at the proximal femur were found in this male sample. The results indicate that 25% of peak BMD at this site may be lost by the age of 50 yr in men. We suggest that bone remodeling may be regulated differently at the proximal femur than at other sites.