Endocrine Abstracts

Introduction: TSH suppression therapy by thyroid hormones (TST) in patients with differentiated thyroid cancer (DTC) could be associated with adverse effects on bone metabolism in post-menopausal women. Recent recommendations suggest therefore to minimize time passed under TSH suppression therapy. However data in literature are controversial and few shows results on microarchitecture. This study evaluated bone microarchitecture using High-resolution peripheral quantitative computed tomography (HR-pQCT, XtremeCT; Scanco Medical AG, Switzerland), in post-menopausal women under TST for more than ten years.

Patients and methods: We conducted a descriptive, case-control, cross-sectional study, in 22 menopausal women under TST for more than 10 years (patients), compared with 32 menopausal women without any bone disease (controls). We measured Bone Mineral Density (BMD) by Dual-energy X-ray absorptiometry (DXA), Bone Microarchitecture by HR-pQCT, bone markers (serum osteocalcin and cross laps).

Results: BMI were similar in both groups. PTH was higher in patients (37.2±2.2 ng/l) compared with controls (29.4±2.4 ng/l), P=0.03. TSH was at 0.10±0.03 mUI/L, with duration of TST of 17.9±1.2 years. No differences were observed between the two groups for bone markers. Hip and lumbar spine BMD were not impaired in patients group. However radial cortical bone density value (Dcomp) was lower in patients (Dcomp at the radius: 816.7±24.5 g/cm³ vs 863.3±11.3 g/cm³ in controls, P=0.04).

Conclusions: This preliminary study shows an adverse effect of TST on radial Dcomp, while BMD is not affected. The trabecular micro architecture is preserved. These preliminary results need to be confirmed and impact of bone breaks need to be studied.