A YOUNG BOY WITH A THYROID YO-YO

We describe a boy with Hashimoto's thyroiditis and Addison's disease w ho was initially hypothyroid, developed hyperthyroidism and eventually became euthyroid, A rise and fall in thyroid binding inhibitory immun oglobulin and thyroid stimulating antibodies were demonstrated to have correlated with the appropriate changes in thyroid status, The fact t hat Hashimoto's thyroiditis can evolve in such a way emphasizes the im portance of lifetime follow-up in these patients.