Degraded Bone Microarchitecture in Women with PHPT–Significant Predictor of Fracture Probability

INTRODUCTION: Patients with primary hyperparathyroidism (PHPT) experience bone mineral density (BMD) loss and trabecular bone score (TBS) alteration, which current guidelines recommend assessing. Considering TBS alongside BMD for a 10-year fracture risk assessment (FRAX) may improve PHPT management. DESIGN: Retrospective, cross-sectional study composed of 49 Caucasian females (62 ± 10.6 years, 27.7 ± 0.87 kg/m(2)) with PHPT and 132 matched control subjects (61.3 ± 10.5 years, 27.5 ± 0.49 kg/m(2)) evaluated in 3 years. We assessed lumbar spine (LS) and femoral neck (FN) BMD, T and Z scores (GE Healthcare Lunar Osteodensitometer) and TBS (iNsight 1.8), major osteoporotic fracture (MOF), and hip FRAX. RESULTS: Patients with PHPT had statistically lower mean values for lumbar spine bone mineral density (LS BMD) (0.95 ± 0.25 vs 1.01 ± 0.14 g/cm(2), P = .01), LS T-scores (−2 ± 0.2 vs −1.4 ± 0.1 SD, P = .009), LS Z scores (−0.9 ± 0.19 vs −0.1 ± 0.11 SD, P = .009), femoral neck bone mineral density (FN BMD) (0.79 ± 0.02 vs 0.83 ± 0.01 g/cm(2), P = .02), FN T-scores (−1.8 ± 0.13 vs −1.5 ± 0.07 SD, P = .017), FN Z scores (−0.51 ± 0.87 vs −0.1 ± 0.82 SD, P = .006), and TBS (0.95 ± 0.25 vs 1.01 ± 0.14 g/cm(2), P = .01) compared with control subjects. 22.4% of patients with PHPT had degraded microarchitecture (TBS < 1.2) vs. 7.6% in control group (χ(2) = 0.008). PHPT proved to be a covariate with unique contribution (P = .031) alongside LS BMD (P = .040) in a linear regression model [R(2) = 0.532, F(4,16) = 4.543] for TBS < 1.2. TBS adjustment elevated MOF FRAX both for PHPT (4.35 ± 0.6% vs 5.25% ± 0.73%, P < .001) and control groups (4.5 ± 0.24% vs 4.7% ± 0.26%, P < .001) compared with BMD-bases FRAX, but also increased differently between the 2 study groups (1.1-folds for PHPT patients and 1.04 for control subjects, P = .034). CONCLUSION: Compared with control, TBS-adjusted FRAX provides significantly higher MOF risk than BMD-based FRAX in PHPT women.