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Editorials |
Department of Clinical Chemistry, Helsinki University Central Hospital, Biomedicum, PB 700, Helsinki, FIN-00029 HUS, Finland
| The first 20% of the full text of this article appears below. |
Most hormones and proteins as well as many drugs are currently determined by immunoassay. Clinicians generally trust that the results they get are correct, but this is not always the case. Several recent studies have described examples of nonspecific interferences producing misleading results. Many of the interfering factors have been known for decades and thoroughly discussed in this and other journals (1)(2)(3)(4); it therefore may seem surprising that gross errors caused by these are not recognized. Overreliance on automation by laboratorians, who may never have learned the basics of immunoassay technology, may have contributed to a situation in which assay problems causing serious clinical misinterpretations remain unrecognized (5). It therefore is highly desirable that false immunoassay results be minimized by improvements in assay design. The approach described by Warren et al. (6) in this issue is an interesting and potentially useful way to achieve this goal.
The specificity of the antigenantibody reaction is astounding; it is possible to measure picomolar concentrations of proteins, peptides, and haptens in the presence of a 10 million-fold excess of closely related molecules, e.g.,
-fetoprotein in the presence of albumin (7). Assays with such low (picomolar) limits of quantification have become possible through the development of sensitive nonisotopic detection methods such as time-resolved fluorometry and luminometry in combination with two-site immunometric methods. Such assays are now available on a wide array of automated analyzers. To increase throughput, many of these
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