Trabecular Bone Score in Obese and Nonobese Subjects with Primary Hyperparathyroidism before and after Parathyroidectomy

Abstract

Context Obesity has been shown to be unfavorable to skeletal microarchitecture when assessed by trabecular bone score (TBS). The influence of adiposity on skeletal microstructure in primary hyperparathyroidism (PHPT) has not yet been evaluated. Objective To investigate the effect of obesity on TBS and bone mineral density (BMD) in subjects with PHPT at baseline and through 2 years after parathyroidectomy. Design Prospective observational study. Setting Referral center. Patients or Other Participants Thirty men and women with PHPT undergoing parathyroid surgery. Main Outcome Measures TBS and BMD by dual-energy X-ray absorptiometry (DXA). Results There were notable improvements in lumbar spine and femoral neck BMD in the obese (lumbar spine: 4.3 ± 4.7%, femoral neck: 3.8 ± 6.6%; P < 0.05 for both) and nonobese subjects (lumbar spine: 3.8 ± 5.6%, femoral neck 3.1 ± 5.0%; P < 0.05 for both) but no marked change in TBS in either group at 24 months postparathyroidectomy. Obese subjects had fully degraded TBS values compared with the nonobese subjects, whose TBS values were minimally below normal throughout the study (baseline: 1.199 ± 0.086 vs 1.327 ± 0.099, respectively; P = 0.003; 24 months: 1.181 ± 0.061 vs 1.352 ± 0.114, respectively; P = 0.001), despite improvements in BMD. Conclusions The detrimental effect of obesity on TBS, an index of bone quality, was demonstrated in subjects with PHPT. Obesity was associated with fully degraded skeletal microarchitecture as measured by TBS in PHPT, despite similar values in bone density by DXA compared with nonobese subjects. TBS values did not improve postparathyroidectomy in either obese or nonobese subjects.