ANTIRESORPTIVE THERAPY IN HYPERTHYROID PATIENTS - LONGITUDINAL CHANGES IN BONE AND MINERAL METABOLISM

The effect of antiresorptive therapy with nasal calcitonin (CT) in rec ently diagnosed hyperthyroid patients on conventional medical therapy as well as the evolution of bone metabolism were assessed. Forty-five patients with recent-onset hyperthyroidism (<12 weeks) were sex and me nopause stratified and randomly allocated to treatment with carbimazol e (Neotomizol), carbimazole plus low dose CT (Calsynar; 100 IU/day, 2 days/week), or carbimazole plus high dose CT (Calsynar; 100 IU/day, 14 days/month). Bone mineral density was measured by dual x-ray absorpti ometry in lumbar spine, femoral neck, and Ward's triangle at 0, 9, and 18 months of treatment. We also determined free T-4, free T-3, TSH, o steocalcin, total and bone alkaline phosphatases, tartrate-resistant a cid phosphatase, type I collagen C telopeptide, and urinary hydroxypro line every 3 months of follow-up. No significant difference was observ ed among treatments. A euthyroid state was attained at 3 months. Bone mass increased significantly at the 9 month evaluation (P < 0.05), wit h a 5-10% net gain during follow-up. Nevertheless, final bone mass was 4-8% smaller than expected. Bone formation markers were increased at 0 and 3 months, with reductions at 6-9 months; resorption bone markers showed a significant reduction at the 3 month evaluation. These resul ts indicate that the euthyroid state partially reduces hyperthyroidism -associated osteopenia, with a bone mass recovery period during the 6- 9 early months of effective treatment. This recovery phase is characte rized by raised bone formation markers and reduced bone resorption mar kers. The treatment with nasal CT at the doses assayed has no addition al effect over that of attainment of the euthyroid state.