Men's Osteoporosis Support Group

Which T-score determines osteoporosis?

J Clin Densitom. 2008 Jul 1. [Epub ahead of print], Use of Lowest Single Lumbar Spine Vertebra Bone Mineral Density T-Score and Other T-Score Approaches for Diagnosing Osteoporosis and Relationships with Vertebral Fracture Status. Chen P and others. PMID: 18599331.

If you have ever gotten a copy of your dual energy X-ray absorptiometry (DXA) test results you were probably confused by all the information. Which score is important, which can you ignore, etc.? This article sheds some light on this topic and should make your DXA results more meaningful.

International Society for Clinical Densitometry guidelines suggest using the lowest bone mineral density (BMD) T-score from the following: lumbar spine (LS), femoral neck (FN), or total hip (TH). Rather than selecting any one lumbar vertebra, guidelines suggest the total spine (L1-L4) score should be used.

Based upon the results of the Multiple Outcomes of Raloxifene Evaluation trial which involved 2560 women, the authors note that using a single LS T-score rather that TS would produce 20% more osteoporosis diagnoses in women in the study. However, there would be no difference in the total number of prevalent fractures or for predicting the risk of future fractures. The authors conclude, "Thus, the WHO diagnostic classification should not be applied to single vertebral T-scores. This analysis supports the current International Society for Clinical Densitometry position to use the total spine T-score for osteoporosis diagnosis."

Editor's comments. T-scores used to diagnose osteoporosis are a non-invasive means of predicting future fracture risk. The idea is to prevent fracture by selecting high-risk individuals with a method that will allow treatment for those at the greatest risk of fracture. Using a single vertebral T-score would include 20% more individuals than when using total spine (L1-L4) T-score, but wouldn't prevent any more fractures. So, to be diagnosed with osteoporosis, an individual should have a T-score equal to or less than -2.5 S.D. in either the total spine (L1-L4), the femoral neck, or the total hip. A single vertebra with that score would not place an individual in the osteoporosis category if all other test results are greater than -2.5 S.D.

Return to Home