More than 10% of postmenopausal women in the United States receive thyroid hormone replacement therapy and up to 20% of these women are over-replaced inducing subclinical hyperthyroidism. Because hyperthyroidism and post menopausal osteoporosis overlap in women of advancing age, it is urgent to understand the effect of thyroid hormone excess on bone. We can now provide results that not thyroid hormones but also TSH itself has an equally important role to play in bone remodeling.