Age-related change in the strength of correlation of lumbar spine bone mineral density with other regions

Abstract Objectives: To investigate whether the strength of correlation of lumbar spine bone mineral density (BMD) with other regions differs with age. Methods: Subjects were 336 premenopausal women aged 20–49 years and 218 postmenopausal women aged 50–69 years with right-side dominance. Age, height, weight, and years since menopause (YSM) were recorded. Subjects were classified into five subgroups at 10-year increments. BMD of the arms, lumbar spine (L2-4), pelvis, legs, and total body were measured by dual-energy X-ray absorptiometry (DEXA). Results: Regional and total body BMD did not differ among women aged in their 20s, 30s, and 40s. However, in women aged over 50, regional and total body BMD gradually decreased with age. The strength of correlation of lumbar spine BMD with the left arm, right arm, left leg, right leg, and total body BMD gradually increased with advancing age ( r =0.422–0.715, 0.376–0.714, 0.476–0.721, 0.491–0.734, and 0.642–0.800, respectively). However, the strength of correlation of lumbar spine BMD with pelvis BMD remained unchanged ( r =0.512–0.622). Conclusions: Correlation of lumbar spine BMD with extremities BMD gradually strengthens with advancing age, while higher correlation of lumbar spine BMD with pelvis BMD remains unchanged. When lumbar spine BMD is predicted using values at sites such as forearm BMD, we should consider the patient's age.