Context: Bone loss and nonvertebral fractures have been reported in patients with differentiated thyroid carcinoma (DTC) undergoing thyroid-stimulating hormone (TSH) suppressive therapy. Radiological vertebral fractures (VFs) are an early and clinically crucial marker of bone fragility.
Objective and design: A cross-sectional study to evaluate the prevalence and determinants of radiological VFs in women receiving l-thyroxine (L-T4) therapy for DTC.
Patients and interventions: A total of 179 consecutive women (median age, 59 years; n = 178 postmenopausal) who had undergone thyroidectomy for DTC and were currently receiving L-T4 were evaluated for radiological VFs and bone mineral density (BMD). There were three TSH target levels [<0.5 mU/L, group 1 (n = 83); 0.5 to 1.0 mU/L, group 2 (n = 50); >1.0 mU/L, group 3 (n = 46)].
Results: VFs were found in 51 patients (28.5%), with significantly (P < 0.001) higher prevalence in group 1 (44.6%) as compared with group 2 (24.0%) and group 3 (4.3%). VF prevalence was not significantly different among patients in group 1 with normal BMD, osteopenia, or osteoporosis, whereas in groups 2 and 3, VFs were more frequent in patients with osteoporosis than in those with either osteopenia or normal BMD. In the whole population, VFs were significantly and independently associated with TSH level <1.0 mU/L; densitometric diagnosis of osteoporosis at lumbar spine, femoral neck, or total hip; age of patients; and duration of L-T4 therapy.
Conclusion: The prevalence of VFs was high in women with DTC who were undergoing long-term, suppressive L-T4 therapy.