Diagnostic discrepancies between two closely related forearm bone density measurement sites

At the present time the diagnosis of osteoporosis is based on the use of T- scores. Measurements at different skeletal sites or of different regions of interest may result in diagnostic discrepancies. In this study, we tried t o demonstrate that bone mineral density (BMD) values at the closely related forearm sites may lead to diagnostic uncertainty, and to assess the degree of site heterogeneity across different age groups. The study consisted of 2348 women (age 20-83) referred for bone densitometry. Forearm BMD was meas ured at the distal and ultradistal sites by single X-ray absorptiometry (DT X-100 device). T-scores were calculated from Bulgarian reference data. Diag nostic disagreement: between sites was found in 19.3% of all women. In 7.7% of all cases, the difference between T-scores at the two sites exceeded 1. The discrepancies were more pronounced after age 60. This corresponds well to the different onset and rates of trabecular and cortical bone losses as well as to their different distribution along the forearm. We encourage th e separate assessment of cortical and trabecular bone densities or measurem ents at axial sites in case forearm sites yield conflicting results or low- normal BMD values.