Bisphosphonates are less effective in women receiving TSH-suppressing doses of thyroxine. - GreenMedInfo Summary
Osteoporosis and thyrotropin-suppressive therapy: reduced effectiveness of alendronate.
Thyroid. 2009 May;19(5):437-42. PMID: 19415993
Department of Endocrinology and Molecular and Clinical Oncology, University of Naples Federico II, Naples, Italy.
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
RESULTS: After 24 months of treatment group A showed a 7.8% increase in lumbar BMD; group B, a 4.6% increase; and group C, a 0.86% increase. In the control group BMD increased 8.2%. A significant difference was found in both lumbar and femoral BMD increase among the three groups: group C had a lower BMD increase than group A (p<0.001) and B (p<0.001).
CONCLUSIONS: In postmenopausal women who were receiving adequate amounts of calcium and vitamin D in their diet ALN was less effective for those who were also receiving TSH-suppressive doses of LT(4) for either 6 or 9 years. The positive effect of ALN on BMD was less for longer periods of LT(4) treatment. It seems likely that other bisphosphonates would also be less effective in increasing BMD in postmenopausal women receiving TSH-suppressing doses of LT(4).