評估第二代促甲狀腺刺激激素受體抗體之檢測方法於葛瑞夫茲氏症

The Evaluation of The Second Generation Assay for Measuring TSH Receptor Antibody in Graves’ Disease

目的：葛瑞夫茲氏症（Grave’s disease-GD）是造成甲狀腺機能亢進之重要甲狀腺自體免疫疾病，患者血清中存在異常的免疫球蛋白，稱為促甲狀腺刺激激素受體抗體(TSH recepter antibody-TRAb)，它可與存在於甲狀腺濾泡細胞膜上之人促甲狀腺激素受體結合，促使甲狀腺分泌荷爾蒙增多並造成甲狀腺瀰漫性增生（腫大）。TRAb是Graves發病的一個重要因素，這些抗體在Graves病患者中的陽性率約為60-95%，檢測這些自身抗體可用於Graves症的確診和區分其他甲狀腺疾病，繼續監測TRAb的值可有助於判斷疾病的預後及復發，由此可見檢測TRAb是很重要！但臨床檢測時亦有10-40%TRAb未能檢測出TRAb，因此我們評估更敏之新方法，以期有更安全、簡便操作、更準確的檢測方法。本實驗將分析比較慣用之放射受體法（ridioreceptor assay--RRA）試劑組與新方法酵素免疫分 析法（enzyme-linked immunosorbent assay --ELISA）試劑組之間的精密度、準確度、敏感度、特異性、相關性，並建立 ELISA法之參考值。方法： 使用RRA法與ELISA法測試甲狀腺疾病之病人（n=105）及健康人（n=74）之血清中的TRAb。結果： RRA法inter assay A血清為26.12﹪±2.04﹪（N=10），CV=7.66﹪；B血清為44.69﹪ ± 2.81﹪ （N=10） ，CV=6.29﹪ 。Between assayA血清為27.71﹪±2.7﹪（N=10），CV=9.74﹪；B血清為44.5﹪±2.32﹪（N=10），CV=5.21﹪。ELISA法之inter assay A血清為34.27﹪±1.98﹪（N=10），CV=5.77﹪；B血清為90.61﹪ ±0.78﹪（N=10），CV=0.86﹪；C血清為73.09﹪±1.08﹪（N=10），CV=1.47﹪。Between assayA血清為34.27﹪±3.05﹪（N=10），CV=8.86﹪；B血清為89.64﹪±2.16﹪（N=10），CV=2.41﹪。RRA法與ELISA法R=0.95；P＜0.001，所以兩種方法相關顯著。RRA法陽性率為64/105（60.95%），ELISA法陽性率為78/105（74.3%）；ELISA法之參考值為＜10%。結論： 因使用豬的促甲狀腺素受體（ T S Hreceptor-TR）之放射受體法，有放射性使用安全性及放射性廢棄物處理之考量，且與使用人的促甲狀腺素受體（TSHreceptor-TR）之酵素免疫析法比較分析後，酵素免疫析法具有較高的臨床敏感性和特異性及操作簡便，且酵素免疫分析法之有效期限較RRA長，更有利於臨床彈性應用，另外更重要是可提供更準確數值，所以使用酵素免疫分析法是為很好的考量。

Background: TSH receptor antibody (TRAb) plays important role in Graves’disease. The measurement of TRAb is performed currently by radioreceptor assay (RRA)to detect porcine TSH receptor (PTR) . However, TRAb is undetectable in about 10% to 40% of patients Graves’ disease by using this method. The second generation assay by using ELISA to detect human TSH receptor (HTR) as a means to measure TRAb is therefore investigated in the present study. Method: TRAb in the quality control sera were measured by RRA and ELISA respectively to compare their inter-assay and intra-assay. TRAb in the sera of 90 patients (24 females and 66 males with mean age of 39.9 y /o) Graves’ disease were measured both by the RRA and ELISA methods.Besides, TRAb in the sera of 74 age and sex matched control subjects were also measured by these two assays method. Result: The inter assay of control serum A and serum B by using RRA methodwas 26.12% ± 2.04% (N=10, CV = 7.66%)and 44.69% ± 2.81% (N=10, CV = 6.29%),respectively The intra assay of control serum A and serum B by RRA was 27.71% ± 2.70% (N=10, CV = 9.74%)and 44.5% ± 2.32% (N=10, CV = 5.21%), respectively whereas the inter assay of control serum A and serum B by using by ELISA method was 34.27% ± 1.98% (N=10, CV = 5.77%)and 90.61% ± 0.78% (N=10, CV = 0.86%),respectively The intra assay of control serum A and serum B by ELISA was 34.27% ± 3.05% (N=10, CV = 8.86%),and 89.64% ± 2.16% (N=10, CV = 2.41%), respectively The correlation coefficient between RRA and ELISA was significant (r = 0.94, P < 0.001). The sensitivity of RRA assay was 65.6% (59/90), and that of ELISA assay was 75.6% (68/90). The specificies of both RRA and ELISA assays were 100% (74/74).The nomal reference value of TRAb by using ELISA was below 10%. Conclusion:measurement of TRAb by detecting HTR using ELISA METHOD has higher sensitivity and specificity than that bydetecting PTR using RRA method.