Table 1.
Geometric mean of 25(OH)D concentrations (ng ml−1) in 20 volunteers, by centrifuging time, collection tube, and type of assay
| 2 h Geometric mean (range) |
24 h Geometric mean (range) |
72 h Geometric mean (range) |
96 h Geometric mean (range) |
All times combined Geometric mean (range) |
|
|---|---|---|---|---|---|
| Chemiluminescence immunoassay (CLIA/LIAISON®) | |||||
| No additive—serum | 15.4 (6.4, 62.4) | 16.3 (6.3, 64.5) | 14.5 (6.6, 60.4) | 15.1 (5.4, 59.0) | 15.3 (5.4, 64.5) |
| Heparin—plasma | 16.1 (6.3, 61.6) | 16.7 (6.1, 60.0) | 15.3 (6.4, 56.1) | 16.6 (6.6, 62.3) | 16.1 (6.1, 62.3) |
| EDTA—plasma | 15.6 (6.3, 63.5) | 14.5 (6.9, 59.4) | 15.3 (7.0, 58.1) | 15.7 (6.1, 56.6) | 15.3 (6.1, 63.5) |
| All tubes combined | 15.7 (6.3, 63.5) | 15.8 (6.1, 64.5) | 15.0 (6.4, 60.4) | 15.8 (5.4, 62.3) | 15.6 (5.4, 64.5) |
| Radioimmunoassay (DiaSorin RIA) | |||||
| No additive—serum | 16.0 (6.1, 59.2) | 16.1 (6.7, 57.8) | 16.7 (7.2, 68.2) | 16.1 (5.9, 58.3) | 16.2 (5.9, 68.2) |
| Heparin—plasma | 15.9 (5.4, 53.8) | 16.4 (5.5, 58.5) | 17.0 (7.6, 58.9) | 16.9 (7.2, 59.1) | 16.5 (5.4, 59.1) |
| EDTA—plasma | 15.5 (7.5, 56.2) | 15.5 (5.0, 65.1) | 16.1 (5.8, 58.3) | 15.6 (5.3, 54.8) | 15.7 (5.0, 65.1) |
| All tubes combined | 15.8 (5.4, 59.2) | 16.0 (5.0, 65.1) | 16.6 (5.8, 68.2) | 16.2 (5.3, 59.1) | 16.1 (5.0, 68.2) |
Abbreviations used CLIA Chemiluminescence immunoassay; RIA Radioimmunoassay