Suitability of the T-score for establishing bone mineral density categories.

The use of different reference ranges may give rise to different T-score values for the same bone mineral density (BMD) value. This study was designed to quantify the differences in the classification of a particular population on the basis of normal ranges obtained from other reference databases. The T-scores obtained in a sample of 148 women by applying the Spanish normal range were compared with the normal range obtained in NHANES III for femoral neck. Significant differences were found when T-scores were compared, but there were no differences in categorizations using the WHO criteria. The application of these reference ranges to a female population aged older than 45 years with known BMD showed significant differences in classification. In conclusion, the T-score can vary according to the normal range used as reference, but it has little influence on the categorization of individual patients. However, it may be important when applied to a general population.