DXA-based bone strain index in normocalcemic primary hyperparathyroidism

The trabecular and cortical bone assessed by bone strain index seems not to be significantly affected in NHPT. Introduction The natural history and bone involvement of normocalcemic hyperparathyroidism (NHPT) are not fully clarified yet. The bone strain index (BSI) is a deformation index based on the finite element method and can be applied to DXA scans. In this study, we aim to assess BSI in subjects with NHPT. Method A case-control study included 170 subjects: 40 subjects with NHPT, 50 subjects with primary hypercalcemic hyperparathyroidism (PHPT), and 80 controls (age- and sex-matched with the NPTH group). Results Lumbar spine (LS) bone mineral density (BMD), femoral neck (FN) BMD, total hip (TH) BMD, and TBS were similar between NHPT and both PHPT and controls. FN-BSI was lower in NHPT compared to PHPT (1.52 +/- 0.31 vs 1.72 +/- 0.42 p = 0.031) while there were no differences between NHPT and controls. TH-BSI was lower in NHPT compared to PHPT (1.36 +/- 0.23 vs 1.52 +/- 0.34, p = 0.030), while there were no differences between NHPT and controls. LS-BSI was not different between NHPT and both PHPT and controls. Conclusion The trabecular and cortical bones assessed by BSI seem not to be significantly impaired in NHPT. Further prospective studies are needed to confirm these findings and to give an insight into the natural history of NHPT to improve knowledge and management of this condition.