DEVELOPMENT AND VALIDATION OF AN AUTOMATED LATEX-ENHANCED IMMUNOASSAYFOR PREALBUMIN

The measurement of circulating prealbumin has been shown to be clinica lly useful in the assessment of nutritional status, both as an initial screen and in the monitoring of nutritional recovery. We describe a f ully automated, noncompetitive, homogenous, light-scattering immunoass ay that has been developed for this analyte on a Dimension(R) (Dade) a nalyzer. A sheep anti-prealbumin IgG fraction was covalently coupled t o 40-nm chloromethyl styrene particles and, after the addition of samp le, polyethylene glycol-assisted immunoagglutination was monitored by turbidimetry. The prealbumin working assay range was 8-550 mg/L at a s ample volume of 2 mu L and a reaction time of 6.5 min. When data were analyzed using ANOVA, total and within-run assay imprecision values (C Vs) were 1-5%, and calibration and reagent stabilities were in excess of 40 days. Mean analytical recoveries were 102% +/- 4% (SD), and ther e was no lack of parallelism. Hemolysis, lipemia, and bilirubin did no t interfere. Both plasma anticoagulated with heparin or EDTA and serum from plain or serum-separation tubes were acceptable as sample matric es. Comparison with the Beekman Array(R) method gave a Passing and Bab lok regression of: Dimension analyzer = 1.01Beckman + 7.1 (n = 103), u sing a common calibrator. We conclude that the prealbumin method is ap propriate for clinical use according to the analytical criteria used i n this study.