BONE-MINERAL DENSITY IN CHILDREN AND ADOLESCENT FEMALES TREATED WITH HIGH-DOSES OF L-THYROXINE

Single-photon absorptiometry was used to assess forearm bone mineral c ontent (BMC) at a proximal site (PBMC) and at a more distal site (DBMC ) of the non-dominant distal forearm in 20 children and adolescent fem ales taking high doses of L-thyroxine (120 mu g/m(2)/day) for a period of 6-96 months for endemic goiter, Hashimoto's thyroiditis or thyroid cancer. PBMC was significantly reduced compared to controls (p < 0.00 2). No correlation was found between PBMC, the values of circulating t hyroid hormones and the indices of tissue hyperthyroidism such as TSH and systolic time intervals (STI), suggesting that bone is a very sens itive target for thyroid hormones. Further studies are necessary to co nfirm our findings and to verify their clinical significance. At prese nt, we believe that suppressive doses of L-thyroxine should be reserve d for cancer patients only.