Levothyroxine and Bone

Abstract

Thyroid hormones play an important role in the development of the skeleton in children, and in maintaining bone mineral content in adults. Hyperthyroidism is associated with loss of bone mineral content, with increased risk of fractures. This has raised concerns that treatment (especially over treatment) with levothyroxine (LT4) might mimic these adverse effects on the skeleton. Clinical data on the effects of LT4 administration on bone are conflicting. In general, the use of LT4 to maintain euthyroid levels of thyroid hormones in patients with hypothyroidism, or even the use of thyrotropin-suppressive therapy following removal of thyroid tumours, does not appear to carry a substantial risk of osteoporosis or fractures. Nevertheless, a cautious approach to avoid over treatment is recommended, especially in patients with or at risk of developing osteoporosis.