Division of Endocrinology, Diabetology and Clinical Nutrition, Department of Medicine 1, University Hospital of Schleswig-Holstein, Campus Kiel, Kiel, Germany.
Institute of Clinical Chemistry, University Hospital of Schleswig-Holstein, Campus Lübeck, Lübeck, Germany.
J Clin Endocrinol Metab. 2019 Dec 1;104(12):5840-5842. doi: 10.1210/jc.2019-01321.
Immunoassay interference has been most often found with prolactin measurement. However, only few data exist on immunoassay interference for other hormones.
A 36-year-old woman with obesity (body mass index, 31 kg/m2) had regularly attended our endocrine unit for type 2 diabetes therapy. When she was included as a control subject in a study for obesity management, detailed laboratory testing was performed, including PTH. In the absence of clinical symptoms, she presented with normal calcium, phosphate, and vitamin D levels. However, the PTH levels were >5000 ng/L. These results were obtained using the Roche Elecsys electrochemiluminescence assay. Repeated measurements with this assay (mouse antibody) led to the same findings. However, using an Euroimmun assay (goat antibody), the exact PTH values were measured at 18.0 ng/L. After pretreatment with a heterophilic antibody blocking reagent, the results of the Roche assay had decreased to a normal level. This phenomenon was explained by the detection of human anti-mouse antibodies in the proband's serum.
In cases of prolactin immunoassay interference, endogenous antibodies will bind to the hormone in vivo, resulting in complexes of a high molecular weight that are less efficiently cleared by the kidneys and, thus, accumulate in the blood. In contrast, the PTH values >5000 ng/L detected in our subject most likely had resulted from the specific interference of the human anti-mouse antibodies present in the proband's serum with the assay antibody, resulting in artificial stimulation of the Roche assay detection system ex vivo.
免疫测定干扰最常发生在催乳素测量中。然而，关于其他激素的免疫测定干扰，仅有少数数据存在。
一位 36 岁的肥胖女性（体重指数 31kg/m2）定期到我们的内分泌科接受 2 型糖尿病治疗。当她被纳入肥胖管理研究的对照组时，进行了详细的实验室检查，包括甲状旁腺激素（PTH）。尽管她没有出现临床症状，但钙、磷和维生素 D 水平正常。然而，PTH 水平>5000ng/L。这些结果是使用罗氏 Elecsys 电化学发光分析法获得的。使用该检测方法（鼠抗体）进行了重复测量，结果相同。然而，使用 Euroimmun 检测方法（羊抗体），准确的 PTH 值测量值为 18.0ng/L。在用异嗜性抗体阻断试剂预处理后，罗氏检测方法的结果降低至正常水平。这种现象是由于在该患者的血清中检测到人类抗鼠抗体而导致的。
在催乳素免疫测定干扰的情况下，内源性抗体将在体内与激素结合，形成高分子量的复合物，这些复合物的清除效率较低，因此在血液中积累。相比之下，我们的患者检测到的 PTH 值>5000ng/L 很可能是由于患者血清中存在的人类抗鼠抗体特异性干扰了检测抗体，导致罗氏检测系统在体外被人为刺激。
