INFLUENCE OF THYROXINE TREATMENT ON THYROID SIZE AND ANTITHYROID PEROXIDASE ANTIBODIES IN HASHIMOTO THYROIDITIS

OBJECTIVE It has been postulated that a decrease in thyroid size can be achieved by thyroxine treatment in patients with goitrous Hashimoto's thyroiditis but no objective data are available. We have therefore investigated the influence of thyroxine treatment on ultrasonically determined thyroid size. We also measured serum antithyroid peroxidase antibodies. DESIGN Consecutive patients with goitrous Hashimoto's thyroiditis was studied. PATIENTS Thirteen women participated; all had goitrous thyroiditis. TREATMENT To render them euthyroid thyroxine was given for 24 months. MEASUREMENTS Thyroid size was measured ultrasonically and antithyroid peroxidase antibodies were measured using a commercial radioimmunological method. RESULT Concomitant with the gradual increase in serum free thyroxine and free triiodothyronine index values and a fall in serum thyrotrophin level, a gradual decrease in thyroid volume from 50.4 +/- 6.8 ml (mean +/- SEM) to 34.1 +/- 5.7 ml (32%), P < 0.001 was demonstrated. Antithyroid peroxidase antibodies were present in high concentrations in all subjects but the mean serum level was not significantly changed at 24 months after initiation of treatment. CONCLUSION A clinically significant reduction in thyroid volume related to normalization of thyroid function but unrelated to changes in antithyroid peroxidase antibody can be achieved during L-thyroxine treatment of hypothyroid goitrous Hashimoto's thyroiditis.