Hypothyroidism Preceding Hyperthyroidism in a Patient with Continuously Positive Thyroid Stimulating Antibody

Abstract

A 62-year-old woman was initially hypothyroid and then developed hyperthyroidism with continuously positive thyroid-stimulating antibody (TSAb). When she visited our hospital with the complaint of the feel of skipping beats, her serum free T₄ level was initially low and thyrotropin (TSH) level was slightly elevated. One month after starting the supplement therapy with 1-T₄, she developed hyperthyroidism with increased ¹²³I-thyroid uptake. TSH-binding inhibitor immunoglobulin (TBII) was slightly elevated only during the hypothyroid stage. Throughout the whole course, TSAb was continuously positive, while thyroid stimulation-blocking antibody (TSBAb) was not detectable. Primary hypothyroidism with TSAb may suggest the possibility of subsequent development of hyperthyroidism.
(Internal Medicine 34: 247-250, 1995)