Preoperative change of thyroid stimulating hormone receptor antibody level: possible marker for predicting recurrent...

To make the surgical treatment for Graves' disease more ideal, it is important to elucidate factors related to postoperative thyroid dysfunction in addition to thyroid remnant. Because TSH receptor antibody (TRAb) is thought to be one of the essential causes of Graves' disease, we investigated whether preoperative changes in serum TRAb levels are related to postoperative recurrent hyperthyroidism. Between 1987 and 1992 a total of 1520 patients with Graves' disease were treated by subtotal thyroidectomy. Of these patients 335 visited Ito Hospital with no history of drug treatment of their disease and were treated surgically after several courses of antithyroid drug (ATD) therapy. There were 68 males and 267 females with a mean age of 25.8 years. The mean follow-up period was 48 months (range 12-84 months). Factors analyzed by univariate and multivariate analysis were as follows: age, sex, duration of ATD treatment, weight of resected thyroid, weight of thyroid remnant, preoperative titer of MCHA, TRAb at the time of initial examination (TRAb1), TRAb at the time of surgery (TRAb2), and DeltaTRAb, the difference between TRAb1 and TRAb2 (DeltaTRAb = TRAb1 - TRAb2). The chi-square test was used for univariate analysis and a logistic model for multivariate analysis. Of this group, 119 patients were euthyroid (35.5%), 50 were hyperthyroid (14.9%), and 166 were hypothyroid (49.3%). Significant factors related to recurrent hyperthyroidism were weight of thyroid remnant and DeltaTRAb in both univariate and multivariate analyses. DeltaTRAb is a possible new marker for predicting postoperative recurrent hyperthyroidism. If the preoperative TRAb level is not improved by ATDs in patients with Graves' disease, the thyroid remnant should be made smaller.