Postpartum recurrence of hyperthyroidism and changes of thyroid-stimulating immunoglobulins in Graves' disease

The changes of circulating thyroid-stimulating antibody (TSAb) in three patients with Graves' disease with relapsed hyperthyroidism after delivery were examined. All three patients were in clinical remission before and during pregnancy, but hyperthyroidism, with high radioactive iodine uptake, recurred 3--5 months post partum. TSAb activity, measured serially, was not detected at the time of the postpartum relapse, although it was detectable during pregnancy and in the euthyroid state after therapy. In two cases, the titer of antithyroid microsomal antibody increased concomitantly with an increase in the free T4 index. These data suggest that TSAb may not be a pathological thyroid stimulator in patients with recurrent hyperthyroidism after delivery in Graves' disease.