Circulant anti-triiodothyronine antibodies in a patient with graves' disease: effects on measurement of T3 with different ria procedures

Abstract High levels of triiodothyronine have been found in a patient with Graves' disease caused by circulating antibodies able to bind specifically with serum triiodothyronine. High values found were due to the interference of the endogenous antibody with the conventional techniques of radioimmunoassay used for the evaluation of the hormone. An analytical pattern to identify these antitriiodothyronine antibodies is described.