INFLUENCE OF CLINICAL CHARACTERISTICS AND PARAMETERS ASSOCIATED WITH THYROID-HORMONE THERAPY ON THE BONE-MINERAL DENSITY OF WOMEN TREATED WITH THYROID-HORMONE

Reports of reduced bone mineral density (BMD) in patients receiving lo ng-term replacement and suppression therapy with L-thyroxine have gene rated considerable interest and controversy. A substantial literature has evolved, with interpretation of conflicting results obscured by a variety of confounding factors. We examined the BMD measurements of 20 2 white women who were taking thyroid hormone to determine the contrib ution to BMD of a number of clinical characteristics and parameters as sociated with thyroid hormone therapy. Measurements of BMD (N=335 over 2.6 F 1.6 years) of the spine (L(2)-L(4)) were performed in 195 subje cts. The BMD of three sites of the hip was measured (N=247 over 1.8 +/ - 1.1 years) in 157 subjects. The BMD of the proximal radius was also measured (N=172 over 1.8 +/- 1.2 years) in 124 subjects. Increasing ag e and a history of previous thyrotoxicosis had a deletrious effect on spine BMD. Body mass index (BMI) was positively correlated with spine BMD. Dose of thyroid hormone, duration of therapy, type of underlying thyroid disease, history of thyroidectomy, or serum-free thyroxine ind ex did not influence either the initial BMD or the change in spine BMD over time. In the hip, age correlated with a decrease, and BMI with a n increase in BMD. A history of previous thyrotoxicosis was associated with a decrease in hip BMD at all three sites (0.05 <p <0.01). No oth er clinical parameters significantly influenced either the initial BMD or the change in hip BMD over time. Increasing age and dose of thyroi d hormone, and a prior history of thyrotoxicosis had a deleterious eff ect on the BMD at the proximal radius. In summary, thyroid hormone the rapy was not associated with a significant effect om BMD of the spine or hip, but a decreased BMD of the proximal radius was related to both previous thyrotoxicosis and to dose of thyroid hormone.