25OH Vitamin D Total Assay - University of California, San Francisco

Plasma
METHOD COMPARISON
TRUENESS
UNIVERSITY OF CALIFORNIA SAN FRANCISCO, CLINICAL LABORATORIES
Repeatability P1 P2 P3 P4
Number of determinations 80 80 80 80
Mean (ng/mL) 5.91 45.9 52.6 62.7
Standard Deviation (ng/mL) 0.48 1.51 1.71 3.25
Coefficient of Variation (%) 8.1 3.3 3.2 5.2
Reproducibility P1 P2 P3 P4
Number of determinations 80 80 80 80
Mean (ng/mL) 5.91 45.9 52.6 62.7
Standard Deviation (ng/mL) 0.75 3.19 3.65 4.92
Coefficient of Variation (%) 12.7 6.9 6.9 7.9
A total of 155 samples was tested by LIAISON 25 OH Vitamin D TOTAL and by DiaSorin 25 OH
Vitamin D RIA. The resulting regression equation was:
LIAISON = 0.99 (RIA) + 2.4; R = 0.97.
The assay trueness has been verified by the dilution and recovery tests.
1. Dilution Test:
Five samples were diluted with LIAISON 25 OH Vitamin D TOTAL Specimen Diluent and
analyzed. The results were analyzed as a linear regression of the Expected vs. Observed values.
The resulting regression equation is: Observed = Expected 0.99 + 0.1; R = 0.99.
2. Recovery Test
High concentration samples were mixed with low concentration samples in ratios of 1:2, 1:1, and
2:1. The observed values were then compared to the expected values to determine the %
recovery. The mean recovery is 102%.
Sample 1
High neat
2 H : 1 L
1 H : 1 L
1 H : 2 L
Low neat
Expected Concentration
(ng/mL)
35.1
30.6
26.0
Observed Concentration
(ng/mL)
44.0
34.1
32.1
25.7
17.2
% Recovery
97%
105%
99%
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