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Clin Biochem. 2004 Feb;37(2):105-11.

Differences in urinary albumin detected by four immunoassays and high-performance liquid chromatography.

Author information

1
Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia. wayne.comper@med.monash.edu.au

Abstract

OBJECTIVES:

To compare the analysis of urinary albumin from diabetic patients by four conventional immunoassays including radioimmunoassay (RIA), immunonephelometry (IN), and two different methods of immunoturbidimetry (IT), as well as by high-performance liquid chromatography (HPLC).

DESIGN AND METHODS:

Urines were collected over a 24-h period and stored at -20 degrees C until assay. Urinary albumin concentration was determined by an in-house RIA, by IN using a Beckman Array Analyser with reagents from Beckman Diagnostics (Sydney, Australia), by IT using a Dade-Behring Turbitimer with reagents from Dade-Behring (Marburg, Germany), by IT using a Dade-Behring Dimension R x L Chemistry Analyser with reagents from DiaSorin (Stillwater, OK, USA), and by HPLC using a Zorbax Bio series preparative GF-250 column. Regression lines were calculated using a least squares method to determine the correlation between the assays studied. Bland-Altman bias plots including limits of agreement were also calculated.

RESULTS:

The correlation coefficients calculated were high (>0.85) indicating a strong linear relationship between all assays studied. The slopes calculated for the comparisons demonstrate that each assay can vary from one another (up to threefold) and have a slope significantly different from an ideal slope of 1 (P < 0.001). These results were confirmed by Bland-Altman bias plots and calculation of the limits of agreement that were all large.

CONCLUSIONS:

At this time, there is no global standard by which urinary albumin assays may be standardized. This study suggests the need for such standards.

PMID:
14725940
[Indexed for MEDLINE]

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