Comparison of Trabecular Bone Score (TBS) and Bone Mineral density (BMD) in patients with Type 2 Diabetes Mellitus (T2DM) and Primary Hyperparathyroidism (PHPT)

Document Type

Conference Proceeding

Publication Date

2-1-2022

Publication Title

J Bone Miner Res

Abstract

It is well known that fracture risk is increased in both T2DM and PHPT, but the mechanisms for increased fracture risk may be different in these endocrine disorders as BMD is usually low, normal or even higher in T2DM whereas it is often low in PHPT. Accordingly, we studied BMD and TBS in a convenience sample of patients with T2DM & PHPT.Methods: BMD and TBS were simultaneously measured by standard methods on Hologic DEXA instrument in 25 T2DM and 20 PHPT patients. This sub-study was part of a larger study to assess bone quality by digital tomosynthesis. There were 2 Asians, 11 blacks, and 12 whites in the T2DM group and 9 blacks and 11 whites in the PHPT groups (no difference in the proportions between the 2 groups). All PHPT patients had hypercalcemia and elevated or non-suppressed PTH levels. All T2DM patients had normal serum calcium levels (PTH was not measured). Renal function as assessed by serum creatine was normal (<1.5 mg/dl) in both groups.Results: The mean age of the T2DM was 61 +/- 10y and that of PHPT was 68 +/- 8y (p=0.012). Mean BMI was similar (25.2 +/- 4.1 Vs. 25.7 +/- 3.0; p=ns). Mean BMD in T2DM was normal and significantly higher than in the PHPT group (1.016 +/- 0.173 Vs. 0.89 +/- 0.17 g/cm2; p=0.02) as were the corresponding lumbar spine BMD T-scores (-0.7 +/- 1.5 Vs. -1.9 +/- 1.5SD; p=0.011). Mean TBS was similar (1.34 +/- 0.11 Vs. 1.31 +/- 0.074; p=ns) in the 2 groups, but significantly lower than the 14 normal healthy controls with normal BMD and similar BMI as the study groups (TBS in healthy controls 1.43 +/- 0.072). Because of the significant age difference between the 2 groups, a multivariable model was used with age forced into the model. T2DM patients still had a higher BMD (p=0.04) and T-score (p=0.03) than the PHPT patients in this model.Conclusions: Despite higher BMD, T2DM and PHPT patients had similar TBS, which was lower than normal. This implies that the abnormal TBS in the 2 conditions studied with dissimilar BMD is caused by different mechanisms such as advanced glycation in T2DM and higher PTH in PHPT. Our results should be interpreted with caution as the sample sizes are small. Further investigations on the mechanistic reasons for the abnormal TBS warrant further study.It is well known that fracture risk is increased in both T2DM and PHPT, but the mechanisms for increased fracture risk may be different in these endocrine disorders as BMD is usually low, normal or even higher in T2DM whereas it is often low in PHPT. Accordingly, we studied BMD and TBS in a convenient sample of patients with T2DM & PHPT.

Volume

37

First Page

145

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