Biotin interference in streptavidin/biotin-based immunoassays has been recently recognized as a confounding factor in clinical settings. Depending on the nature of the assay, the presence of excess biotin in patient samples can cause falsely high or low results. One of the platforms known to be affected, Roche Cobas, is widely used in anti-doping laboratories to test for intact chorionic gonadotropin (hCG) in urine. While biotin levels in blood have been well studied, less is known about urinary biotin due to its limited clinical significance. Having analyzed over 4,000 urine samples, we have established a reference range for urinary biotin with a median concentration of approximately 12 ng/ml. However, a significant number of samples contain much higher amounts, with a maximum approaching 10 μg/ml, suggesting biotin supplementation. Consequently, the tolerance of hCG STAT assay towards biotin was investigated over a wide concentration range. The apparent hCG concentration was found to decrease almost linearly as biotin increased from 100 to 1,000 ng/ml, with only 10% of the expected value reported by the assay as biotin reached 1,000 ng/ml. Further increase of biotin resulted in a progressive, albeit more moderate, decline in measured hCG concentration. To avoid a false negative result in the context of anti-doping analysis, it is highly recommended to monitor biotin in urine and perform diafiltration before hCG measurement in samples with elevated biotin to remove the interference.

中文翻译：

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生物素作为使用生物素化抗体的绒毛膜促性腺激素测定中的掩蔽剂

链霉亲和素/基于生物素的免疫测定中的生物素干扰最近被认为是临床环境中的一个混杂因素。根据检测的性质，患者样本中存在过量的生物素可能会导致错误的高或低结果。已知受影响的平台之一是 Roche Cobas，广泛用于反兴奋剂实验室，以检测尿液中完整的绒毛膜促性腺激素 (hCG)。虽然血液中的生物素水平已经得到很好的研究，但由于其有限的临床意义，对尿生物素的了解较少。在分析了 4,000 多个尿液样本后，我们建立了尿液生物素的参考范围，中位浓度约为 12 ng/ml。然而，大量样本的含量要高得多，最大值接近 10 μg/ml，这表明补充了生物素。所以，在很宽的浓度范围内研究了 hCG STAT 测定对生物素的耐受性。随着生物素从 100 增加到 1,000 ng/ml，表观 hCG 浓度几乎呈线性下降，当生物素达到 1,000 ng/ml 时，该测定报告的预期值只有 10%。生物素的进一步增加导致测量的 hCG 浓度逐渐下降，尽管更温和。为避免在反兴奋剂分析中出现假阴性结果，强烈建议监测尿液中的生物素，并在生物素升高的样品中进行 hCG 测量之前进行渗滤，以消除干扰。当生物素达到 1,000 ng/ml 时，检测报告的预期值只有 10%。生物素的进一步增加导致测量的 hCG 浓度逐渐下降，尽管更温和。为避免在反兴奋剂分析中出现假阴性结果，强烈建议监测尿液中的生物素，并在生物素升高的样品中进行 hCG 测量之前进行渗滤，以消除干扰。当生物素达到 1,000 ng/ml 时，检测报告的预期值只有 10%。生物素的进一步增加导致测量的 hCG 浓度逐渐下降，尽管更温和。为避免在反兴奋剂分析中出现假阴性结果，强烈建议监测尿液中的生物素，并在生物素升高的样品中进行 hCG 测量之前进行渗滤，以消除干扰。