Clinical value of the free thyroxine and free triiodothyronine ration combined with thyrotropin in predicting differentiated thyroid carcinoma / 中国医师进修杂志

ABSTRACT

Objective To investigate the value of free thyroxine (FT4) and free triiodothyronine (FT3) ratio (FT4/FT3) combined with thyrotropin (TSH) in predicting differentiated thyroid carcinoma (DTC). Methods The clinical data of 109 thyroid nodules patients having underwent surgery were retrospectively analyzed. Postoperative pathological findings showed 61 cases of DTC (malignant group) and 48 cases of benign thyroid nodules (benign group). The independent risk factors of DTC were screened out by univariate analysis and multivariate Logistic regression analysis. The receiver operating characteristic (ROC) curve was drawn. The area under the curve (AUC) was calculated, and the best cut-off value was obtained. Results There was no significant difference in the sex composition and FT4 between malignant group and benign group (P ＞ 0.05). The age and FT3 levels in malignant group were significantly lower than those in benign group (44.48 ± 12.07) years vs. (52.81 ± 12.99) years and (4.31 ± 0.61) pmol/L vs. (4.73 ± 1.05) pmol/L, the FT4/FT3 and TSH were significantly higher than those in benign group 3.70 ± 0.62 vs. 3.26 ± 0.70 and 2.15 (1.42, 2.78) mU/L vs. 1.63 (1.05, 2.19) mU/L, and there were statistical differences (P＜0.01 or ＜0.05). Multivariate unconditional Logistic regression analysis result showed that FT4/FT3 and TSH levels were risk factors for DTC ( OR = 2.398 and 1.804, 95% CI 1.084 - 5.306 and 1.130 - 2.880, P = 0.031 and 0.013). The AUC of FT4/FT3, TSH and FT4/FT3 combined with TSH were 0.661 (95% CI 0.556-0.766, P=0.004), 0.663 (95% CI 0.561-0.764, P=0.004) and 0.726 (95% CI 0.632-0.820, P=0.000). The best cut-off values of FT4/FT3 and TSH were 3.346 and 1.845 mU/L. The sensitivities were 70.5% and 62.3% , and the specificities were 60.4% and 64.6%. The sensitivity and specificity of FT4/FT3 combined with TSH were 85.2% and 50.0%. Conclusions FT4/FT3 and TSH levels are risk factors for DTC. The greater the FT4/FT3 level, the higher the TSH level, the higher the risk of DTC. When FT4/FT3＞3.346 and/or TSH＞1.845 mU/L, the clinical value of combined prediction for DTC is higher.