Background Chromogranin A (CgA) is a hydrophilic and acidic protein, present in the chromaffin granules of neuroendocrine cells. It is the preferred tumor marker for the monitoring of neuroendocrine tumors (NETS), which are often found in the lungs, appendix, pancreas, and gastrointestinal tract. Previous CgA assays were performed by manual ELISA testing, and were not FDA-approved, leading to a longer, more rigorous validation process and longer run times. The introduction of an automated, FDA-cleared CgA assay allows the laboratory to process patient samples more quickly and reliably, shortening a multiple hour process to minutes. The objective of this study was to evaluate the performance of an automated CgA assay recently cleared by the FDA. Methods We validated the the B·R·A·H·M·S™ Chromogranin A II (CGAII) assay on the automated B·R·A·H·M·S KRYPTOR Compact PLUS (Thermo Fisher Scientific Inc.). The CGAII assay is an immunofluorescent assay, which uses Time-Resolved Amplified Cryptate Emission (TRACE) to quantitate CGA in human serum. Assay performance characteristics were evaluated including measuring range (MR) and maximum dilution, precision, method comparison, stability, reference interval, stability, and carryover. Results The MR for CGAII was established with triplicate analysis of serum at 8 levels, ranging from 25.8 - 2,700 ng/mL. Linearity was demonstrated with a slope of 0.907, intercept of 1.948 and observed error of 2.54 ng/mL. Recovery at each point ranged from 83.3-110.3%. Carryover (<5.0 ng/mL) was not observed at a concentration approximately 2 times the upper limit of the MR. A 1:25 or 1:500 automatic dilution was determined to be acceptable (% bias <16%). Intraday precision coefficient of variation (CV) ranged from 4.1-1.7% (SDs from 2.32-6.64 ng/mL) at concentrations of 56.7 and 393.0 ng/mL. The interday CVs ranged from 6.0-7.1% (SDs from 3.43 - 28.84 ng/mL) at concentrations of 57.5 and 403.8 ng/mL. Twenty samples with concentrations ranging from 56.4-2,907 ng/mL were compared to a reference laboratory utilizing a similar methodology. The correlation coefficient was 0.9934, with a slope of 1.014, and intercept of -32.95. An additional twenty samples with concentrations ranging from 67.0-2,446 ng/mL were compared to a CgA ELISA kit (CGA-ELISA-NG, CISBIO) to determine the bias between the two methodologies. The correlation coefficient was 0.9902, with a slope of 0.845, and intercept of -15.31, and a bias of -19.9%. The serum samples were stable for 3 days when stored at 2-8°C. Recovered CgA concentrations fell outside of the 95% confidence interval after day 3 at 2-8°C. The manufacturer provided reference interval of <187 ng/mL was verified by testing 20 healthy adult samples, all of which fell within this range. Conclusions This assay has been validated and shown to be an accurate and precise method for monitoring CgA. Further, the method was validated on an automated analyzer to allow expeditious turnaround time in a core laboratory.

中文翻译：

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B-316 在自动分析仪上评估经 FDA 批准的嗜铬素 A 测定


背景 嗜铬蛋白 A (CgA) 是一种亲水性酸性蛋白质，存在于神经内分泌细胞的嗜铬颗粒中。它是监测神经内分泌肿瘤 (NETS) 的首选肿瘤标志物，神经内分泌肿瘤常见于肺、阑尾、胰腺和胃肠道。以前的 CgA 测定是通过手动 ELISA 测试进行的，未经 FDA 批准，导致验证过程更长、更严格，运行时间更长。引入经 FDA 批准的自动化 CgA 检测使实验室能够更快速、更可靠地处理患者样本，将数小时的流程缩短至几分钟。本研究的目的是评估 FDA 最近批准的自动 CgA 检测的性能。方法 我们在自动化 B·R·A·H·M·S KRYPTOR Compact PLUS (Thermo Fisher Scientific Inc.) 上验证了 B·R·A·H·M·S™ 嗜铬粒蛋白 A II (CGAII) 测定。 CGAII 测定是一种免疫荧光测定，它使用时间分辨放大穴状化合物发射 (TRACE) 来定量人血清中的 CGA。评估分析性能特征，包括测量范围 (MR) 和最大稀释度、精密度、方法比较、稳定性、参考区间、稳定性和残留。结果 CGAII 的 MR 通过对 8 个水平（范围为 25.8 - 2,700 ng/mL）的血清进行三次重复分析而建立。线性度为 0.907，截距为 1.948，观测误差为 2.54 ng/mL。每个点的回收率范围为 83.3-110.3%。在大约 2 倍 MR 上限的浓度下未观察到残留 (<5.0 ng/mL)。 1:25 或 1:500 自动稀释被确定为可接受（% 偏差 <16%）。日内精度变异系数 (CV) 范围为 4.1-1.7%（标准差为 2.32-6）。64 ng/mL），浓度为 56.7 和 393.0 ng/mL。浓度为 57.5 和 403.8 ng/mL 时，日间 CV 范围为 6.0-7.1%（SD 为 3.43 - 28.84 ng/mL）。使用类似的方法将浓度范围为 56.4-2,907 ng/mL 的 20 个样品与参考实验室进行比较。相关系数为0.9934，斜率为1.014，截距为-32.95。将另外 20 个浓度范围为 67.0-2,446 ng/mL 的样品与 CgA ELISA 试剂盒（CGA-ELISA-NG、CISBIO）进行比较，以确定两种方法之间的偏差。相关系数为0.9902，斜率为0.845，截距为-15.31，偏倚为-19.9%。血清样品在 2-8°C 下保存可稳定 3 天。第 3 天后，2-8°C 下回收的 CgA 浓度超出了 95% 置信区间。制造商提供的 <187 ng/mL 参考区间通过测试 20 个健康成人样本进行验证，所有样本均落在该范围内。结论 该测定已被验证并被证明是一种准确且精确的 CgA 监测方法。此外，该方法在自动分析仪上进行了验证，以允许核心实验室加快周转时间。