A rapid, simple measurement of human albumin in whole blood using a fluorescence immunoassay (I).

BACKGROUND Human serum albumin (HSA) is the most abundant plasma protein and plays key a role in metabolism. The variation in albumin concentration provides valuable information related to metabolic diseases and diagnostic application. METHODS We constructed two assay systems to quantify the albumin concentration. The immunoassay used a fluorescence (FL) dye to detect albumin in samples and employed the conventional chromatography as a separation system. The assay system consists of an anti-HSA-mAb or an HSA immobilized test strip in a disposable cartridge, a fluorescence-labeled detector buffer and a laser-fluorescence scanner. We mixed the sample with detector, loaded it onto a cartridge, incubated it for 10 min and measured the concentration of albumin in a laser-fluorescence scanner. We examined the comparability of assay with an automated BCG dye binding method using a Hitachi 747 biochemical analyzer. RESULTS The correlation of coefficient between AT/AC as converted from the relative fluorescence units (RFU) and albumin concentration displayed reasonable reliability in both the competition and the inhibition assay systems (r = 0.998). Using the Bland-Altman difference plot analysis, we observed an acceptable agreement between two methods, the fluorescence immunochromatography assay (FL-ICA) and the automated BCG dye-binding method of a Hitachi biochemical analyzer, over the clinical relevant range of HSA concentrations. The coefficient of variation (CV) of within- and between-run variation in the immunoassay system was < 8% and the recovery fell within 5% in each control sample. In addition to its reliable analytical performance, the assay with whole blood can be completed in 12 min using a one-step operation without any pretreatment. CONCLUSION The developed immunoassay system using fluorescence dye and lateral-flow chromatography is a simple, fast and reliable method for quantifying the albumin concentration in whole blood.