The effect of thyroid hormone on bone metabolism and osteoporosis

Thyrotoxicosis has long been known to accelerate bone turnover and thus increase the risk for developing osteoporosis, especially in periand postmenopausal women. Increasingly sophisticated tests of thyroid function have indicated that minor degrees of hyperthyroidism are common in patients taking thyroxine (T4) therapy. Recent reports have suggested that women taking TSH-suppressive doses of T4 have reduced bone density. An overview of the effects of thyroid hormone on bone metabolism is presented. The use of sensitive TSH assays can now permit extremely accurate titration of the T4 dosage and should obviate the potential side effects of excessive therapy that results in iatrogenic subclinical thyrotoxicosis.