Clinical Assays for Human Chorionic Gonadotropin

Abstract

Within the last year, human chorionic gonadotropin (hCG)2 has been a topic of great discussion in both the scientific and popular press. Recent reports have demonstrated that because of hCG’s heterogeneity, assay standardization is an important problem, with different immunoassays giving different results for the same specimens. In addition there have been reports of false-negative results due to high concentrations of certain hCG variants. Finally, the popular press has reported on illicit use of hCG by athletes for performance enhancement and by dieters for weight loss. In all, these publications raise questions about what variants of hCG are currently being measured, what should be measured, and how best to do it. In this Q&A article, 5 leaders in the field have been asked to comment on current clinical assays for hCG and what the future might hold. Catharine Sturgeon3 : I think it is really important that laboratories know the specificity of the method used as the specificity needs to be different for pregnancy and cancer applications. It’s important to know the extent to which different hCG variants are recognized in different methods. The highly purified WHO International Reference Reagents (IRR) for 6 hCG-related isoforms, which were produced by the IFCC Working Group for hCG, now enable manufacturers to characterize the extent to which their immunoassays measure those important isoforms. Reaching consensus about how best to assess this, as well as how to present the data so as to allow easy comparison of methods, will represent a major step forward. Studies to assess the influence of calibrator purity on results are also in progress. Thankfully, we can now describe the major variants using the systematic and user-friendly nomenclature developed by the IFCC Working Group. We all need to work hard to encourage its universal adoption. Since the IRR …