ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2008) 16 P716

Effects on bone mineral density of supraphysiological levothyroxine doses in patients with differentiated thyroid carcinoma

Miguel Angel Mollar-Puchades, Antonia Perez-Lazaro, Juan Francisco Merino-Torres, Monica Muñoz-Vicente, Raquel Segovia-Portoles, Vicente Campos-Alborg, Ma Soledad Navas-de Solis & Francisco Piñon-Selles

Unit of Endocrinology, University Hospital La Fe, Valencia, Spain.

Introduction: The treatment of differentiated thyroid carcinoma exposes most patients to chronic supraphysiological doses of thyroid hormone which seems to have several negative effects for the patient. The goal of the present study was to assess the consequences of these doses on the bone mineral density (BMD).

Patients and methods: We performed a cross-sectional study on 64 female patients followed up between 1972 and 2007. We registered the levothyroxine doses over the last 3 years and the anthropometric parameters. All patients were tested for their hormonal situation and underwent a BMD study on hip and lumbar spine by DXA. For the statistic analysis, we performed the corresponding parametric and nonparametric tests to compare means and establish correlations.

Results: Out of 64 patients, 71.4% (n=45) were menopausal and 28.6% (n=19) were premenopausal. The time of evolution was higher in the menopausal patients (15.9 vs 8.8 years, P<0,05) and the levothyroxine dose was higher in the premenopausal patients (2.45 vs 2.15 μg/kg, P<0,05). According to the levothyroxine dose, those patients receiving over 2.2 μg/kg or 100 μg/m2 showed a decrease in their T and Z Scores, compared with those who were receiving a lower dose. The results were significant in the premenopausal women, in both areas, whereas in the menopausal ones, the significant results were those in the lumbar spine. The menopausal patients who had received a dose over 100 μg/m2 had osteopenia in the lumbar spine (Spine T Score −1.54).

The dose of levothyroxine in premenopausical patients had a negative and significant correlation with hip T Score (r=−0.692) and spine T Score (r=−0.470).

Conclusion: In our study, those patients receiving higher doses of levothyroxine showed a decrease in the BMD parameters. In the menopausal patients, this decrease resulted in osteopenia in the lumbar spine.