The fracture risk in primary hyperparathyroidism (PHPT) is partially independent of bone mineral density (BMD) and seems to depend on decreased bone quality, which is still reliably assessed only with invasive techniques. Trabecular bone score (TBS) is a grey-level texture measurement acquired during a dual X-ray absorptiometry (DXA) lumbar spine scan and it has been recently proposed as index of bone quality. This study is aimed to assess the role of TBS in predicting vertebral fractures (VFx) in PHPT patients.
We prospectively enrolled 92 PHPT patients (18 eugonadal males and 74 post-menopausal females, aged 62.7±10.1 years) and 98 age, gender and BMI matched controls. In all subjects, TBS and BMD at spine (LS) and femur (FN) were assessed (reported as Z-scores) by DXA and VFx by X-ray. Among the 92 PHPT patients, we also report the available longitudinal BMD, TBS and VFx data after 24 months of follow-up for 20 subjects operated on and for 10 conservatively treated.
PHPT patients had lower BMD (LS −0.74±1.14, FN −0.67±0.84) and TBS (−2.39±1.8), and higher prevalence of VFx (43.5%) than controls (0.51±1.46, 0.05±0.85, −0.98±1.07 and 8.2%, respectively, P<0.0001). The presence of VFx was associated with TBS (OR 1.6; 95%CI 1.2 21, P<0.001) regardless of LS BMD, age, BMI and gender. TBS showed the best compromise between sensitivity (75%) and specificity (61.5%) for detecting VFx as compared to BMD (LS 31% and 75%, FN 64% and 65%, respectively). After 24 months, in the 20 patients surgically treated, no new VFx occurred and BMD tended to increase (Z-score change LS 29.9±34.1% and FN 30.2±39.3%, P=NS), while TBS increased significantly (52.8±46.6%, P=0.004). In the 10 patients conservatively treated BMD and TBS tended to decrease (Z-score change LS −11.1±46.1%, FN −29.7±85.3%, TBS −139±235%, P=NS). In the 3 patients with a new VFx, TBS decreased significantly (Z-score change −441.6±217.9%) as compared to those without new VFx (−9.4±14.9%, P<0.05), at variance with BMD (LS −40±10% vs 1.4±50% and FN −36.7±103% vs −13.3±16.1, P=NS).
Conclusions: In PHPT, bone quality, as measured by TBS, is reduced and improves after surgery. TBS appears to be more useful than BMD in detecting PHPT patients at risk of fractures.
27 Apr - 01 May 2013
European Society of Endocrinology