Analytic Performance of a Point-of Care Instrument for Measurement of Human Chorionic Gonadotropin Hormone

Abstract

The aim of the study was to examine and validate the feasibility of the point-of care instrument the Stratus® CS STAT Fluorimetric Analyzer (Dade Behring, Inc, Deerfield, IL) for measurement of hCG. The Stratus® βHCG procedure is a 2-site sandwich fluorimetric immunoassay that measures the intact hCG dimer and the free β form in plasma from heparinized blood (on-board centrifugation) or in previously separated plasma or serum in less than 15 minutes. The analytic performance was compared with the Vidas® assay (bioMérieux, Marcy l'Étoile, France), according to the Valtec protocol designed by the French Society of Clinical Biology. Within-run and between-run coefficients of variation were less than 3%. The linearity extended to 1250 IU/L, and the detection limit was under 1 IU/L. Comparative methods gave: The differences observed between SCS and Vidas are explained by the different specificities of antibodies used and by the influence of heparin on βhCG SCS (−10%). We verified that there was no hook effect with high concentrations of hCG (2 × 106 IU/L) and no interference with FSH or LH. This assay is a good tool in the diagnosis of early detection of pregnancy.