Thyroid Hormone, Osteoporosis, and Estrogen

As noted by Schneider and colleagues1 in this issue of THE JOURNAL, thyroid hormone (levothyroxine sodium) is one of the most frequently prescribed drugs in the United States. Postmenopausal women are particularly prone to develop hypothyroidism, thyroid nodules, and thyroid cancers and are therefore far more likely than men to be taking thyroid hormone, either for replacement therapy or suppression therapy.2 Unfortunately, older women are also at high risk for progressive bone loss from thyroid hormone, as documented in a number of previous studies and summarized in the article by Schneider et al.1 The risk of bone loss is greatest in those women taking larger thyroid hormone doses and seems to be minimal in women taking more modest doses.1 Although the degree of skeletal demineralization observed in many studies places some patients below the fracture threshold in terms of their bone density, no study to date.