Suppressive doses of thyroxine do not accelerate age-related bone loss in late postmenopausal women.

To examine whether suppressive doses of thyroxine have any adverse effects on bone, we evaluated various bone metabolic markers (lectin-precipitated alkaline phosphatase, osteocalcin, carboxyl-terminal region of type I collagen propeptide, tartrate-resistant alkaline phosphatase, and urinary excretion of hydroxyproline and pyridinium crosslinks), incidence of vertebral deformity, total body and regional (lumbar spine and radius) bone mineral densities (BMDs), and rates of bone loss in 24 late postmenopausal (more than 5 years after menopause) women who were treated with levothyroxine (L-T4) after total thyroidectomy for differentiated carcinoma. Depending on the clinical records, including serum TSH levels measured by immunoradiometric assay, these patients were divided into two groups. One group of patients was given suppressive doses of L-T4 (TSH 0.1 mU/L, n = 12). There was no difference in bone metabolic markers and ...