Trabecular Bone Score (TBS) in Primary Hyperparathyroidism (PHPT): A Useful Tool?

Abstract

Primary Hyperparathyroidism (PHPT) often leads to bone loss, even in its asymptomatic presentations. Trabecular Bone Score (TBS) is a method to assess the trabecular bone structure of the spine. This study aimed to evaluate TBS measurements combined with Dual X-ray Absorptiometry (DXA) values in the search for more accurate bone fragility risk assessment among PHPT patients. From 2017 to 2019, patients diagnosed with PHPT (n = 64), before surgery, were invited to participate in this study. Bone mineral density (BMD) by DXA at the lumbar spine, total hip, femoral neck, distal third radius, and TBS were determined in patients and controls (n = 63). The vertebral fracture was defined using the Genant method in vertebral images by DXA and vertebral fracture assessment (VFA). Patients and controls did not differ in age, sex, menopausal status, or body mass index (BMI). The PHPT patients presented significantly lower BMD values than the controls in all sites evaluated. The TBS measurements were also statistically lower in PHPT patients than controls (mean TBS PHPT = 1.233 vs TBS controls = 1.280, p = 0.044). Osteoporosis was observed in 50% of PHPT patients and 26.6% of controls (p = 0.02). However, lumbar spine T-Score < -2.5 was observed only in 21.8% of PHPT patients. Vertebral fractures were detected in nine individuals (14%) from the PHPT group and four (6.3%) in the controls (p = 0.24). The TBS area under the curve (AUC) was higher than DXA AUC in all sites, for vertebral fracture assessment. The TBS AUC was significant in the PHPT group (0.75, 95% CI 0.62 - 0.88, p = 0.02) and not significant in the DXA analysis. The ROC curve showed that TBS values < 1.187 are associated with a significantly higher risk of vertebral fracture among PHPT patients (p = 0.02). The TBS used as a complement to DXA measurements is a useful tool which may better assess fragility risk among PHPT patients.

Keywords: Bone mineral density; Hyperparathyroidism; TBS; Vertebral fractures.