The prediction of risk of differentiated thyroid carcinoma with preoperative serum thyroid stimulating hormone, thyroglobulin and antithyroglobulin antibody

Objectives To explore the values of preoperative serum TSH,Tg,TgAb and TSH/Tg in predicting the risk of differentiated thyroid carcinoma.

Methods 122 patients with thyroid nodules who got operations were studied, Of all, 55 patients with differentiated thyroid carcinoma (54 papillary and 1 follicular),67 cases with benign thyroid nodules(40 nodular goiter and 27 adenoma). TSH and Tg were measured by chemiluminescence method,and TgAb by radioimmunoassay.The postoperative pathological results was regard as the gold standard of diagnosing thyroid cancer.

Results 1. Preoperative serum Tg levels in thyroid cancer group(24.09±64.59) and benign thyroid nodules group (23.37±112.14)had no statistical differences (Z=1.092,P>0.05).TSH levels in thyroid carcinoma group (2.32±2.28) were higher than that in benign thyroid nodules group (1.75±1.22), (Z=2.107,P<0.05).The positive rate of Tg combined with TgAb in thyroid cancer group (72.7%) was higher than that in benign thyroid nodules group(55.2%) (χ²=3.975,P<0.05). 2.Receiver operating characteristic (ROC) curves showing sensitivity as a function of specificity were calculated for TSH,Tg levels and TSH/Tg values to evaluate the potential accuracy of the three index as predicting differentiated thyroid carcinoma.The area under the curve (AUC) of TSH was 0.611, 95% confidence interval (95% CI) for (0.509~0.713),P<0.05.The optimum threshold in ROC curves of TSH was 2.31mIU/L. The sensitivity and specificity of TSH were 71.6% and 50.9% respectively.The AUC of TSH: Tg values was 0.617, 95% CI (0.518 ~ 0.716),P<0.05.The best critical value of TSH/Tg was 0.11 IU/mg. The sensitivity and specificity of TSH/Tg were 61.2% and 50.9% respectively.The AUC of Tg was less than 0.5.

Conclusions 1.Serum Tg elevated abnormally is not an independent predicting factor of differentiated thyroid cancer. 2.The elevated Tg levels and/or positive TgAb and TSH/Tg>0.11IU/mg can be used as effective supplementary means of ultrasound examination in predicting differentiated thyroid carcinoma.