Smoking is associated with lower bone mineral density and reduced cortical thickness in young men

Abstract

Context: Smoking has previously been associated with reduced areal bone mineral density (aBMD) in elderly subjects, but the association remains controversial in adolescents.

Objective: The aim of this study was to determine whether smoking was associated with aBMD or volumetric BMD (vBMD) and bone size in young men.

Design and setting: aBMD was measured using dual x-ray absorptiometry. vBMD and bone size were measured using peripheral quantitative computerized tomography (pQCT). Smoking habits were assessed using questionnaires. Levels of sex steroids, PTH, and 25-OH-vitamin D were measured in serum.

Participants: The population-based Gothenburg Osteoporosis and Obesity Determinants (GOOD) study includes 1068 young men, age 18.9 +/- 0.6 yr (mean +/- SD).

Main outcome measure: The main outcome measure was smoking as predictor of bone parameters and serum sex hormone levels.

Results: Of the study subjects, 8.7% smoked daily. Bone parameters were compared between smokers and nonsmokers. Smokers had significantly lower aBMD (dual x-ray absorptiometry) of the total body (crude: -2.1%; adjusted for age, height, weight, calcium intake, and physical activity: -1.8%), lumbar spine (crude: -4.3%; adjusted: -3.3%), and trochanter (crude: -6.6%; adjusted: -5.0%) than nonsmokers. Using peripheral quantitative computerized tomography, we found that smokers had lower cortical thickness of both the radius (crude: -2.8%; adjusted: -2.9%) and tibia (crude: -4.5%; adjusted: -4.0%) than the nonsmokers, whereas no difference was seen for cortical vBMD. Smokers had higher serum levels of total and free testosterone and lower 25-OH-vitamin D than nonsmokers. Adjustment for testosterone and/or 25-OH-vitamin D levels did not alter the associations between smoking and bone parameters.

Conclusions: We demonstrate that smoking was associated with lower aBMD and reduced cortical thickness in young men.