The structure of human chorionic gonadotrophin (hCG) is so similar to that of luteinizing hormone (LH) that a variety of assay techniques have been devised to differentiate between these two hormones. The principal indications for measurement of hCG using these methods have not changed greatly over the past decade but the improvements in the sensitivity, specificity and the development of assays for free subunits and metabolic fragments have expanded the use of hCG assays. The review discusses the use of hCG measurement in a routine clinical immunoassay laboratory and emphasizes different requirements for clinical situations.
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