1. Chemistry Education Number 1 Comparison of Urine Protein recovery between the ARCHITECT c8000 and the VITROS methods
March 2006
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2. Urine/CSF Protein (UPro; 7D79)
A customer method comparison with VITROS demonstrated significant differences with some patient specimens
Cause:
Protein in urine may be a heterogenous mixture.
The dose-response characteristics for each protein component differ, both within an assay and between assays.
This phenomenon has been well established. (See Dube J et al. Clin Biochem 2005; 38: 479.)
The VITROS assay uses a pyrocatechol dye (reflectance colorimetric method)
The Abbott c8000 assay uses benzethonium chloride as a protein precipitant (turbidimetric method)
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3. Urine/CSF Protein (UPro; 7D79)
Sample
VITROS Result
(mg/dL)
c 8000 Result 1 61
40.2 2
124.3
121.2 3
737.4
484.1 4
14.8
18.1 5
181.9
142.4 6
186
117.5 7
248
142.2 8
46.6 41 9
24.3 21 10 11 12 13
118
106 14 66
141 15
A customer run of 15 patient samples demonstrated differing results between the two urine protein methods.
Samples with clinically significant differences are highlighted.
The ARCHITECT c8000 result is higher in some samples and lower in others when compared to the VITROS result.
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4. Urine/CSF Protein (UPro; 7D79)
Variation in recovery is characteristic of automated urine protein assays due to the heterogeneous protein composition of urine samples. The sample protein composition influences recovery when analyzed using these three methods and will determine the bias when performing method comparison.
Table from page 9 of VITROS UPRO package insert; Pub. No. J04089_EN
NOTE: UPRO slide corresponds to Vitros method
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5. Urine/CSF Protein (UPro; 7D79)
Conclusion
Based on the different methodologies used for Urine Protein measurement on the VITROS and Abbott Chemistry Systems, patient values may vary due to the protein composition of the patient samples.
Variations in recovery due to the heterogeneous protein composition of urine samples are characteristic of automated urine protein assays.
The sample protein composition influences recovery when analyzed using these three methods and will determine the bias when performing method comparison.
The protein composition of the sample can be determined using protein electrophoresis
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