Large Bone not Necessarily High Bone Mineral Density: Evidence from a National Survey

There is scarcity of population-level data on the bone areal size (BA) that produces the highest bone mineral density (BMD), and how BA relates to BMD among racial groups. We use population-level data to estimate the BA that coincide with the highest BMD among racial groups in the United States. A total of 7425 participants, age 18-75 years, whose BA and BMD were measured in the United States National Health and Nutrition Examination Survey (NHANES) 2009-2014, were assessed in this study. Multiple regression models were used to estimate race-specific relationships between BA and BMD. The critical BA that associates with the highest (peak) BMD among racial groups adjusted for confounders was estimated. Results showed a curvilinear relationship between BA and BMD at the population level such that BMD increases with BA at lower values and then decreases after a peak value. Races combined, BA of about 45 cm² seems to correspond to a peak femur BMD in this sample. The peak BMD was different among racial groups. The BA at which BMD peaks was lower among blacks and Mexicans compared to whites. We conclude that femur BMD increases up to a critical femur BA and then decreases thereafter. Persons with femur BA at or close to the critical value may tend to have higher than average BMD.