Endocrine Abstracts

Introduction: Several studies have demonstrated a high incidence of vertebral fractures (VF) in acromegaly, not always correlated with bone mineral density (BMD) value adquired by dual X-ray absorptiometry (DEXA). At trabecular level, GH may alter bone microarchitecture (BM) that predisposes to bone fragility. Trabecular Bone Score (TBS), a textural parameter applied to DEXA to evaluate BM, could be useful to predict VF risk in these patients.

Materials and methods: A cross-sectional study was carried out in acromegalic patients followed up at our hospital between 1989 and 2016. DEXA with Horizon DXA system (Hologic^®) to assess lumbar (L1-L4) BMD and TBS value (TBS iNsight®), spine X-ray and blood tests to evaluate hormonal status and bone metabolism were performed. DXA and TBS results were compared with a healthy control group. TBS ≥ 1.35 corresponded to a normal BM (NBM), 1.2-1.35 to a partially degraded BM (PDBM) and ≤1.2 to a degraded BM (DBM).

Results: Twenty-six acromegalic patients meeting criteria of disease control by IGF1 levels (53.8% women; age 59.3±15.6 and median BMI 28.4 kg/m²) and 128 control subjects (53.1% women; age 50.9±20.3 and median BMI 24.9 kg/m²) were evaluated. TBS was lower in patients compared with control (1.26±0.13 vs 1.35±0.18; P=0.01), with no significant differences in BMD (g/cm²), T-score and Z-score (0.99±0.2 vs 0.96±0.15; -0.63±1.76 vs -0.95±1.35 and 0.41±1.67 vs -0.22±1.44 respectively). In acromegalic patients no significant relationships were found between IGF-1, gonadal and adrenal status, TBS and lumbar BMD. Patients who had received radiotherapy (RT) had lower TBS than those who had not (1.15±0.08 vs 1.31±0.13; P=0.017). DBM was observed in 80% of acromegalic patients with diabetes mellitus vs 22% in non-diabetics (P=0.05). VF were found in 3 patients, all of them with TBS values corresponding to DBM (TBS 1.09, 1.2 and 1.08).

Conclusions: In our study, acromegalic patients show lower TBS than healthy controls, particulary in RT-treated and diabetic subgroups. This finding suggests alterations in BM that could explain the increased risk of fractures in these patients. More studies are needed, exploring the fracture predictive capacity of TBS in these patients.