High bone mineral density is associated with high body mass index

High BMD is an infrequent finding. In this retrospective cohort study of women 50 years and older, we documented a strong association between high BMD and high BMI.

High bone mineral density (BMD) has been associated with genetic disorders and a variety of dietary, endocrine, metabolic, infectious and neoplastic diseases that in many cases warrant medical attention. Since body mass index (BMI) is closely correlated with BMD, we sought to explore the relationship between these two parameters in older women.

We conducted a retrospective clinical cohort study of 16,500 women 50 years and older who underwent baseline BMD testing between May 1998 and October 2002. Mean T-scores and Z-scores, and the proportions of women with high BMD (T-score +2.5 or greater, Z-score +2.0 or greater), were assessed according to BMI category.

Higher BMI category was associated with higher mean T-scores and Z-scores at all sites (P < 0.001). The proportion of women with high BMD increased with each BMI category (P for trend <0.05). In women with a lumbar spine T-score of +2.5 or more, 43.5% were obese with BMI > 30 kg/m(2) (55.6% for the femoral neck and 73.1% for the total hip). For women with a lumbar spine Z-score of +2.0 or more, 37.2% were obese (42.0% for the femoral neck and 50.9% for the total hip). There was no evidence of a paradoxical increase in fracture rates in women with high BMD.

High BMD is closely associated with elevated BMI in women. This should be taken into consideration prior to initiating extensive investigations for rare pathologies.