HYPOTHYROID GRAVES-DISEASE

Background. Spontaneous conversion from hypothyroidism to hyperthyroid ism has generally been considered uncommon. Methods. Values obtained w ere serum thyroid-stimulating hormone (TSH), thyroxine, free thyroxine index, radioactive iodine uptake (RAIU), thyroid-stimulating immunogl obulins (TSI), and thyrotropin-binding inhibitory immunoglobulin (TBII ). Results. Five patients spontaneously had a minimum of two cycles in thyroid function with extremes of hypothyroxinemia to hyperthyroxinem ia. One patient had four documented cyclic shifts in thyroid status. W hen measurements were obtained in the hyperthyroid phase, all patients had TSI, increased RAIU, and an undetectable TSH. When measurements w ere done in the hypothyroid phase, all patients had positive TBII but negative TSI. Conclusions. Spontaneous reversal of thyroid function ma y be more common than previously thought. Clinical features associated with lability of thyroid function were abrupt change in goiter size, exaggerated response to therapy, or the presence of TSH-receptor antib odies.