Table 3.
Precision and accuracy of vitamin D3 metabolite measurement.
| Compound and concentrations | aIntra-assay (n = 6) | Inter-assay (n = 6) | ||
|---|---|---|---|---|
| bMeasured | c%CV | Measured | %CV | |
| 1α,25(OH)2D3 | ||||
| 50 pg/mL | 48.0 ± 3.3 (96.0%) | 7.0% | 46.4 ± 2.6 (92.8%) | 5.6% |
| 100 pg/mL | 100.3 ± 12.0 (100%) | 11.9% | 102.5 ± 6.8 (103%) | 6.6% |
| 200 pg/mL | 213.1 ± 6.3 (107%) | 2.9% | 206.7 ± 10.6 (103%) | 5.1% |
| native plasma | 85.9 ± 4.6 | 5.3% | 93.4 ± 6.7 | 7.1% |
| 24R,25(OH)2D3 | ||||
| 0.5 ng/mL | 0.50 ± 0.04 (100%) | 8.5% | 0.50 ± 0.07 (100%) | 13.8% |
| 1.0 ng/mL | 1.04 ± 0.07 (104%) | 7.0% | 1.03 ± 0.05 (103%) | 4.6% |
| 2.0 ng/mL | 2.08 ± 0.26 (104%) | 12.4% | 2.07 ± 0.12 (104%) | 5.9% |
| native plasma | 1.19 ± 0.06 | 5.3% | 1.33 ± 0.11 | 8.3% |
| 25OHD3 | ||||
| 10 ng/mL | 9.5 ± 0.2 (95.0%) | 2.1% | 10.0 ± 0.7 (100%) | 7.0% |
| 20.0 ng/mL | 18.8 ± 0.2 (94.0%) | 1.1% | 18.8 ± 0.2 (94.0%) | 1.0% |
| 40.0 ng/mL | 39.8 ± 1.1 (99.5%) | 2.8% | 40.3 ± 0.8 (101%) | 2.1% |
| native plasma | 21.6 ± 0.7 | 3.4% | 23.6 ± 1.1 | 4.7% |
a
Intra-assay precision was obtained from 6 replicates measured in a single assay.
Inter-assay precision was obtained from 6 assays run over a 10 day period.
b
Reported as mean ± standard deviation (accuracy).
c
CV: coefficient of variance is defined as the ratio of the standard deviation to the mean.