低滴度TRAb原发性甲状腺毒症患者TRAb水平与甲状腺131I摄取率的相关性研究

Association between TRAb level and thyroid iodine uptake rate in primary thyrotoxic patients with low titer TRAb

目的:研究无特异性临床表现、低滴度促甲状腺激素受体抗体(TRAb)的原发性甲状腺毒症患者中,TRAb水平与甲状腺 131I摄取率的相关性。 方法:选取初诊的成人原发性甲状腺毒症患者(TRAb<7.00 IU/L)158例。测定患者甲状腺功能、甲状腺过氧化物酶抗体(TPOAb)、甲状腺球蛋白抗体(TgAb)、TRAb和 131I摄取率。根据 131I摄取率分为非降低组(正常范围或升高)98例和降低组60例。比较两组甲状腺激素、TRAb水平的差异;按TRAb水平将患者分为5组,分析TRAb与 131I摄取率的相关性;采用受试者工作特征曲线分析TRAb判断 131I摄取率非降低的有效性和实用价值。 结果:(1)158例甲状腺毒症患者中 131I摄取率降低占38.0%。与 131I摄取率降低组相比, 131I摄取率非降低组促甲状腺激素、FT 3、FT 4、TRAb、TPOAb阳性率均升高( Z=5.159、4.451、3.078、7.417、3.920, P均<0.05)。(2)随着TRAb水平的升高, 131I摄取率非降低患者的比例增多, 131I摄取率降低患者的比例减少,各组之间总的差异有统计学意义( χ^2=56.801, P=0.000)。TRAb≥0.20 IU/L组, 131I摄取率非降低组的敏感性为98.0%,特异性为33.3%;TRAb≥1.75 IU/L组, 131I摄取率非降低组的敏感性为67.3%,特异性为88.3%;TRAb≥3.50 IU/L组, 131I摄取率非降低组的敏感性为35.7%,特异性为93.3%;TRAb≥5.25 IU/L组, 131I摄取率非降低组的敏感性为19.4%,特异性为95.0%。(3)以Youden指数最大的切点为临界点,TRAb=1.56 IU/L为界值时, 131I摄取率非降低组的敏感性为73.5%,特异性为86.7%。 结论:无特异性临床表现、低滴度TRAb的原发性甲状腺毒症患者中, 131I摄取率降低并非罕见。TRAb<3.50 IU/L,必须行 131I摄取率鉴别甲状腺毒症病因。

Objective To study the correlation between thyrotropin receptor antibody(TRAb)titer and thyroid iodine uptake rate in patients with primary thyrotoxicosis and low titer TRAb.All patients had no specific clinical symptoms.Methods A total of 158 newly diagnosed patients with thyrotoxicosis whose TRAb were lower than 7.00 IU/L were included.Thyroid function,thyroid peroxidase antibody(TPOAb),thyroglobulin antibody(TgAb),TRAb,and iodine uptake rate were measured in all patients.According to the iodine uptake rate,they were divided into non-decreased group(at normal range or increased,n=98)and decreased group(n=60).The differences of thyroid hormone and TRAb between the two groups were compared.All patients were further divided into 5 groups according to their TRAb level to analyze the correlation between TRAb and iodine uptake rate.Receiver operating characteristic curves was used to analyze the validity and practicability of TRAb in diagnosing patients with non-decreased iodine uptake.Results(1)Among 158 patients with thyrotoxicosis,38.0%patients had decreased thyroid iodine uptake rate.The level of thyroid stimulating hormone(TSH),free triiodothyronine(FT3),free thyroxine(FT4),TRAb,as well as the positive rate of TPOAb were higher in non-decreased group than those in decreased group(Z=5.159,4.451,3.078,7.417,3.920,all P<0.05).(2)With the increase of TRAb,the proportion of patients with non-decreased iodine uptake were increased and the proportion of patients with reduced iodine uptake were decreased,and the difference between groups was statistically significant(χ^2=56.801,P=0.000).When using TRAb≥0.20 IU/L to diagnose non-decreased iodine uptake,the sensitivity was 98.0%and the specificity was 33.3%.When using TRAb≥1.75 IU/L,the sensitivity was 67.3%and the specificity was 88.3%.When using TRAb≥3.50 IU/L,the sensitivity was 35.7%and the specificity was 93.3%.When using TRAb≥5.25 IU/L,the sensitivity was 19.4%and the specificity was 95.0%.(3)Based on the maximum tangent point of Youden index,when using TRAb equal to 1.56 IU/L as the boundary value to diagnosing non-decreased iodine uptake rate,the sensitivity was 73.5%and the specificity was 86.7%.Conclusion Decreased iodine uptake is not uncommon in patients with low-titer TRAb thyrotoxicosis and without specific clinical symptoms.However,if TRAb is lower than 3.50 IU/L,the iodine uptake rate must be performed to identify the cause of thyrotoxicosis.