The Determination of α1-Microglobulin by Means of an Automated Latex Immunoassay

Polystyrene (latex) particles coated with human anti-α 1 -microglobulin antibodies are used in an automated kinetic assay for α 1 -microglobulin in urine. For values below 12 mg/l, there was no significant difference between two kinds of standard, but above 12 mg/l the results depend on the origin of the α 1 -microglobulin standard. Correlation between values obtained with both standards was good (r 2 = 0.968). The method has a between-run imprecision (CV) of 11-16%. Comparison with two commercial enzyme immunoassays gave a bias of -10% to + 40%, while two nephelometric methods differed by 0% to 23%, possibly because the standards used in these methods were of different origin. These results indicate the necessity of standardization of the determination of α 1 -microglobulin. The detection limit of our method was 0.8 mg/l, enabling the application of the method for epidemiological investigations.