UCLA Olympic Analytical Laboratory, Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, Los Angeles, California, USA.
Drug Test Anal. 2021 Nov;13(11-12):1929-1935. doi: 10.1002/dta.3141. Epub 2021 Aug 27.
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.
生物素在基于链霉亲和素/生物素的免疫分析中的干扰最近被认为是临床环境中的一个混杂因素。根据分析物的性质，患者样本中存在过量的生物素可能导致结果偏高或偏低。已知受到影响的一个平台是罗氏 Cobas，它在反兴奋剂实验室中被广泛用于检测尿液中的完整绒毛膜促性腺激素（hCG）。虽然血液中的生物素水平已经得到了很好的研究，但由于其临床意义有限，尿液中的生物素知之甚少。在分析了超过 4000 个尿液样本后，我们建立了一个尿液生物素的参考范围，中位数浓度约为 12ng/ml。然而，大量样本中含有更高的生物素，最高浓度接近 10μg/ml，提示存在生物素补充。因此，我们研究了 hCG STAT 分析物对生物素的耐受性，检测了广泛的浓度范围。结果发现，当生物素从 100 增加到 1000ng/ml 时，hCG 的表观浓度几乎呈线性下降，当生物素达到 1000ng/ml 时，分析物报告的 hCG 浓度仅为预期值的 10%。进一步增加生物素会导致测量的 hCG 浓度逐渐下降，尽管下降幅度较小。为了避免在反兴奋剂分析中出现假阴性结果，强烈建议在存在高生物素的样本中监测尿液中的生物素，并在 hCG 测量前进行渗滤，以去除干扰。
