Papapetrou P D, Polymeris A, Karga H, Vaiopoulos G
Second Division of Endocrinology, Alexandra Hospital, Athens, Greece.
J Endocrinol Invest. 2006 Nov;29(10):919-23. doi: 10.1007/BF03349197.
Heterophilic antibodies (HA) may interfere in some immunoassays, causing falsely high hormone values, of which practitioners should be aware when measuring calcitonin (CT) used as tumor marker for medullary thyroid carcinoma (MTC). We studied four patients with thyroid nodules, three of whom underwent surgical neck exploration, after an erroneous diagnosis of MTC because of falsely high serum CT eventually proved to be due to HA. One patient had a lingual thyroid, two autoimmune thyroiditis and the fourth a colloid goiter. The minimal incremental CT response to calcium infusion raised our suspicion of possible false high CT values due to HA. There was no linearity of the CT values obtained by testing serial dilutions of the sera in the CT assay, which employs two monoclonal mouse anti-CT antibodies. Addition of normal mouse gamma globulin eliminated the interference by HA in the sera of two patients. Serum assayed in a polyclonal radioimmunoassay using goat anti-CT antibodies gave normal CT values. Finally, incubation of the sera in Heterophilic Blocking Tubes (HBT) eliminated the false CT immunoreactivity. A spontaneous change of the CT serum concentrations was noticed in three patients over several months, apparently due to changing titles of HA. We suggest that, in patients a) whose CT response to calcium or pentagastrin infusion is minimal despite high basal CT values, b) with autoimmune thyroiditis and c) in whom an unexpected change in serum CT concentrations occurs, the possibility of spuriously high CT values because of circulating HA should be considered.
嗜异性抗体（HA）可能会干扰某些免疫测定，导致激素值假性升高，在将降钙素（CT）用作甲状腺髓样癌（MTC）的肿瘤标志物进行检测时，从业者应注意这一点。我们研究了4例甲状腺结节患者，其中3例接受了颈部手术探查，此前他们因血清CT假性升高而被误诊为MTC，最终证实是由HA所致。1例患者有舌甲状腺，2例有自身免疫性甲状腺炎，第4例有胶体甲状腺肿。钙输注后CT的最小增量反应增加了我们对可能因HA导致CT值假性升高的怀疑。在使用两种单克隆小鼠抗CT抗体的CT测定中，对血清进行系列稀释后测得的CT值不存在线性关系。添加正常小鼠γ球蛋白可消除HA对两名患者血清的干扰。使用山羊抗CT抗体的多克隆放射免疫测定法测得的血清CT值正常。最后，将血清在嗜异性阻断管（HBT）中孵育可消除CT的假免疫反应性。在3例患者中，观察到血清CT浓度在几个月内自发变化，显然是由于HA效价的改变。我们建议，对于以下患者应考虑循环HA导致CT值假性升高的可能性：a）尽管基础CT值较高，但对钙或五肽胃泌素输注的CT反应最小的患者；b）患有自身免疫性甲状腺炎的患者；c）血清CT浓度出现意外变化的患者。
