Hypothyroid Graves' disease.

BACKGROUND

Spontaneous conversion from hypothyroidism to hyperthyroidism has generally been considered uncommon.

METHODS

Values obtained were serum thyroid-stimulating hormone (TSH), thyroxine, free thyroxine index, radioactive iodine uptake (RAIU), thyroid-stimulating immunoglobulins (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 hyperthyroxinemia. One patient had four documented cyclic shifts in thyroid status. When measurements were obtained in the hyperthyroid phase, all patients had TSI, increased RAIU, and an undetectable TSH. When measurements were done in the hypothyroid phase, all patients had positive TBII but negative TSI.

CONCLUSIONS

Spontaneous reversal of thyroid function may 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 antibodies.