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

Abstract

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. Retrospective, cross-sectional study composed of 49 Caucasian females (62 ± 10.6 years, 27.7 ± 0.87 kg/m2) with PHPT and 132 matched control subjects (61.3 ± 10.5 years, 27.5 ± 0.49 kg/m2) 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. 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/cm2, 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/cm2, 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/cm2, P = .01) compared with control subjects. 22.4% of patients with PHPT had degraded microarchitecture (TBS < 1.2) vs. 7.6% in control group (χ2 = 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). Compared with control, TBS-adjusted FRAX provides significantly higher MOF risk than BMD-based FRAX in PHPT women.