Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, Department of Internal Medicine, Neurology and Dermatology, Clinic for Endocrinology and Nephrology, University of Leipzig, Leipzig, Germany.
Clin Chem. 2011 Mar;57(3):467-74. doi: 10.1373/clinchem.2010.151688. Epub 2010 Dec 15.
Calcitonin (CT) is a sensitive marker for evaluation of medullary thyroid cancer (MTC). However, CT measurement can vary with assay- and nonassay-dependent factors, and procalcitonin (PCT) measurement has been proposed for evaluating questionable increases in CT.
We tested 2 fully automated CT assays (Immulite [IL] and Liaison [LIA]) and 1 nonautomated CT assay (IRMA, Medipan) and compared these results with PCT (Brahms Kryptor). We evaluated preanalytical conditions and PCT cross-reactivity in sera of 437 patients with clinical conditions associated with hypercalcitoninemia. Additionally, we determined the true "nil" CT concentration in 60 thyroidectomized patients and defined CT cutoff concentrations for pentagastrin stimulation testing in 13 chronic kidney disease (CKD) patients and 10 MTC patients.
Markedly decreased CT concentrations were found after storage of sera for >2 h at room temperature and >6 h at 4 °C. Cutoff concentrations for basal and stimulated CT were disease and assay dependent. Proton pump inhibitor therapy was the most frequent reason for increased CT. PCT concentrations were higher in patients with MTC than in patients with CKD without infections (P<0.001). Whereas IL and LIA demonstrated comparable analytical quality, the IRMA gave increased CT concentrations in nil sera and showed cross-reactivity with PCT in patients with concomitant bacterial infection.
IL, LIA, and IRMA detected increased CT concentrations in non-MTC patients and discriminated MTC from CKD patients in pentagastrin tests. PCT assessment may be helpful in the diagnostic work-up of increased CT concentrations in questionable clinical circumstances.
降钙素（CT）是评估甲状腺髓样癌（MTC）的敏感标志物。然而，CT 测量可能会受到检测和非检测相关因素的影响，因此有人提出了降钙素原（PCT）的测量方法来评估可疑的 CT 升高。
我们测试了 2 种全自动 CT 检测方法（Immulite [IL] 和 Liaison [LIA]）和 1 种非自动 CT 检测方法（IRMA，Medipan），并将这些结果与 PCT（Brahms Kryptor）进行了比较。我们评估了 437 例伴有高钙血症相关临床情况的患者的预分析条件和 PCT 交叉反应性。此外，我们还在 60 例甲状腺切除患者中确定了真正的“零”CT 浓度，并在 13 例慢性肾脏病（CKD）患者和 10 例 MTC 患者中确定了五肽胃泌素刺激试验的 CT 截止浓度。
室温下储存血清>2 小时和 4°C 下储存>6 小时后，CT 浓度明显降低。基础和刺激 CT 的截止浓度与疾病和检测方法有关。质子泵抑制剂治疗是 CT 升高最常见的原因。与无感染的 CKD 患者相比，MTC 患者的 PCT 浓度更高（P<0.001）。虽然 IL 和 LIA 表现出可比的分析质量，但 IRMA 在零血清中给出了增加的 CT 浓度，并在伴有细菌感染的患者中与 PCT 发生交叉反应。
IL、LIA 和 IRMA 在非 MTC 患者中检测到 CT 浓度升高，并在五肽胃泌素试验中区分 MTC 与 CKD 患者。在可疑的临床情况下，PCT 评估可能有助于 CT 浓度升高的诊断。
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