Endocrinology Division, Durand Hospital, Buenos Aires, Argentina..
Endocrinology Division, Durand Hospital, Buenos Aires, Argentina.
Clin Chim Acta. 2015 Jul 20;447:43-6. doi: 10.1016/j.cca.2015.04.039. Epub 2015 May 13.
We report a case of interference in thyroglobulin (Tg) measurement in a woman with differentiated thyroid cancer and rheumatoid arthritis history. Due to discordant Tg in relation to TSH concentrations and negative images, we investigated possible interference in the measurement of Tg.
During the follow-up we measured Tg by chemiluminescence (TgQL) using Immulite 2000 immunoassay system. To investigate possible interference in Tg measurement, we made serial dilutions, re-testing of Tg by an alternative method: electrochemiluminescence, Cobas 6000 analyzer (TgEQL), recovery test of Tg and polyethylene glycol (PEG) 6000 precipitation.
During the patient follow-up, the TgQL ranged between <0.3 and 16.1ng/ml. In the evaluated serum samples very high titers of rheumatoid factor (RF) were found. When RF titers were lowered post PEG precipitation, Tg QL concentrations became undetectable.
We describe an unusual case of interference in Tg assay due to RF. When disagreement among Tg concentrations, images and clinical features is observed, we suggest taking into account the evaluation of possible Tg interference to avoid unnecessary complementary exams and inappropriate treatment.
我们报告了一例分化型甲状腺癌和类风湿关节炎病史的女性患者的甲状腺球蛋白（Tg）检测受到干扰的情况。由于 Tg 与 TSH 浓度不一致且影像学检查结果为阴性，我们对 Tg 检测可能存在的干扰进行了调查。
在随访期间，我们使用 Immulite 2000 免疫分析系统通过化学发光法（TgQL）测量 Tg。为了调查 Tg 检测是否存在干扰，我们进行了系列稀释，用替代方法（电化学发光法，Cobas 6000 分析仪（TgEQL））重新检测 Tg，进行 Tg 的回收率测试和聚乙二醇（PEG）6000 沉淀。
在患者随访期间，TgQL 范围在<0.3 和 16.1ng/ml 之间。在评估的血清样本中发现了非常高的类风湿因子（RF）滴度。当 PEG 沉淀后 RF 滴度降低时，TgQL 浓度变得无法检测。
我们描述了一例由于 RF 导致 Tg 检测受到干扰的不寻常病例。当 Tg 浓度、影像学表现和临床特征不一致时，我们建议考虑评估 Tg 干扰的可能性，以避免不必要的补充检查和不适当的治疗。
