Evidence of intrathyroidal accumulation of TSH receptor antibody in Graves' disease

Abstract

To clarify the intrathyroidal accumulation of TSH receptor antibody (TR-ab) produced in the thyroid, adrenalin was injected directly into the thyroid artery of patients with Graves' disease during surgery, allowing serial determination of the TR-ab levels in the thyroidal venous blood. Nine surgical patients (3M and 6F) with Graves' disease and receiving anti-thyroid drugs preoperatively for a period of one to four years were enrolled in this study. Comparison between pre- and post-treatment TR-ab levels revealed continuous increments from the pretreatment levels within 15 min of the injection in five (55.6%) of the nine patients. In three of the five patients, TR-ab levels that had been negative before adrenalin injection became positive 1 min after injection. It is assumed that the increase in the TR-ab level is due to adrenalin-induced constriction of the capillaries in the thyroid tissues, resulting in a voluminous flow of the TR-ab retained in the thyroid into the vein. These findings indicate that the TR-ab level in the peripheral blood does not necessarily reflect precisely the abnormal immunological condition in the Graves' thyroid.