Background Serum ferritin is considered a suitable biomarker of iron-related disorders. However, data about the comparability of results among commercial measuring systems (MSs) are contradictory. We performed an intercomparison study aimed at verifying the current interassay variability and its impact on clinical application of the test. Obtaining this information is vital because manufacturers continue to claim calibration alignment to different WHO preparations, which are not related to each other in terms of traceability. Methods Four widely used MSs were evaluated. The interassay agreement was verified using 39 human serum pools. The recovery of WHO International Standard (IS) 94/572 (the only reference material available at the time of the study) was evaluated, after assessing the material commutability. Finally, an approach for harmonizing ferritin results was proposed. Results Highly significant differences (P < 0.00001) among ferritin concentrations assayed by different MSs were detected and the interassay CV (median 22.9%; interquartile range 21.8–25.5) overlapped the desirable intermethod bias (24.6%). IS 94/572 was commutable for use only with Access and Centaur, with Access being the only MS correctly recovering its assigned value. Accordingly, we used regression data against Access to recalibrate MSs, indirectly aligning them to IS 94/572, with a substantial improvement in degree of harmonization and traceability to higher-order reference. Conclusions The harmonization among evaluated ferritin MSs is far from optimal, with the implementation of traceability to different WHO ISs being a factor of confusion. A recalibration approach, however, would permit measurement harmonization, allowing the use of common decision thresholds.

中文翻译：

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血清铁蛋白测量的统一状态以及用作铁相关疾病标志物的意义

背景 血清铁蛋白被认为是铁相关疾病的合适生物标志物。然而，有关商业测量系统 (MS) 之间结果可比性的数据是相互矛盾的。我们进行了一项比对研究，旨在验证当前的测定间变异及其对测试临床应用的影响。获取此信息至关重要，因为制造商不断声称对不同的 WHO 制剂进行校准，而这些制剂在可追溯性方面彼此不相关。方法 对四种广泛使用的 MS 进行了评估。使用 39 个人血清池验证了测定间一致性。在评估材料的可互换性后，对世界卫生组织国际标准 (IS) 94/572（研究时唯一可用的参考材料）的回收率进行了评估。最后，提出了一种协调铁蛋白结果的方法。结果 不同 MS 测定的铁蛋白浓度之间存在高度显着差异 (P < 0.00001)，并且测定间 CV（中位数 22.9%；四分位数范围 21.8–25.5）与理想的方法间偏差 (24.6%) 重叠。IS 94/572 可互换，仅可与 Access 和 Centaur 一起使用，Access 是唯一正确恢复其指定值的 MS。因此，我们使用针对 Access 的回归数据来重新校准 MS，间接将它们与 IS 94/572 对齐，从而显着提高了协调程度和对高阶参考的可追溯性。结论 评估的铁蛋白 MS 之间的一致性远非最佳，不同 WHO IS 的可追溯性的实施是一个混乱的因素。然而，重新校准方法将允许测量协调，允许使用共同的决策阈值。