[Differential diagnosis of transient destructive thyroiditis from hyperthyroid Graves' disease].

It is clearly important to distinguish transient destructive thyroiditis such as subacute thyroiditis and silent thyroiditis from hyperthyroid Graves' disease to treat patients with thyrotoxicosis appropriately. In patients with hyperthyroid Graves' disease, TSH receptor antibody (TRAb) is positive and thyroidal radioactive iodide uptake (RAIU) is markedly elevated. In contrast, TRAb is negative and RAIU is suppressed less than 5% in patients with transient thyroiditis. Further, we demonstrated that the measurement of erythrocyte zinc concentration is quite useful to distinguish transient thyroiditis from hyperthyroid Graves' disease. Thus, combination of the measurement of TRAb, RAIU and erythrocyte zinc concentration helps us distinguish transient thyroiditis from hyperthyroid Graves' disease.