Association Between Urine Cotinine Levels and Bone Mineral Density in Lumbar Spine and Femoral Neck Among Adult Males

Study Design. Cross-sectional study. Objective. To investigate an association between tobacco exposure as determined by urine cotinine and bone mineral density (BMD) in femoral neck and lumbar spine. Summary of Background Data. Loss of BMD is 1 of the major causes of spine and femoral neck fractures in the elderly population. There is limited literature on risk factors to loss of BMD, in particular, among males. Methods. We analyzed data of 770 males older than 30 years, which were collected from the cross-sectional Fifth Korea National Health and Nutrition Examination Survey, with t tests, analysis of variance, and multiple linear regressions. Results. The means of femoral neck BMD (T score) significantly decreased with increasing age, -0.08, -0.63, and -1.49 in males aged 30 to 40 years, 50 to 69 years, and 70 to 95 years, respectively (P < 0.001). The same trend was observed in lumbar spine BMD. Although education (P < 0.001) and income (P = 0.021) were associated with femoral neck T score, only education (P = 0.034) was associated with lumbar spine T score. The group who had urine cotinine level of more than 10 mu g/mL (active smokers or nonsmokers who were exposed to second-hand smoking) had lower femoral neck T score (-0.43 +/- 0.98) than the group who had cotinine level of 10 +/- g/mL or less (-0.33 +/- 0.89) (P = 0.114). In the multiple linear regressions, age, urine cotinine level, and body mass index were statistically related to femoral neck and lumbar spine T score. Conclusion. Our findings suggest that tobacco exposure by active or passive smoking and lower body mass index seem to exert a negative effect on femoral neck and lumbar spine BMD.