Osteoporosis and Thyrotropin-Suppressive Therapy: Reduced Effectiveness of Alendronate

Background: Many reports of the effect of exogenous thyroxine therapy on bone mineral density (BMD) show a relationship between excess thyroid hormone administration and osteoporosis. The aim of this study was to evaluate the effect of antibone resorptive agents, in particular alendronate (ALN) on BMD in postmenopausal osteoporotic women with thyroid carcinoma who were receiving long-term thyrotropin (TSH)-suppressive therapy with thyroxine. Methods: Seventy-four postmenopausal women with low BMD (T-score ≤−2.5) and differentiated thyroid carcinoma on long-term TSH-suppressive therapy (TSH ≥0.05 and ≤0.1 μU/mL) for about 3–9 years were selected for the study. The patients were divided into three groups according to the length of levothyroxine (LT4) treatment prior to the beginning of the study: group A (TSH-suppressive therapy for about 3 years), group B (for about 6 years), and group C (for about 9 years). These patients were compared with 74 matched women not taking LT4. All patients and controls were t...