Table 3.
Mean ionized magnesium concentrations in fresh, refrigerated and frozen blood samples and mean difference from baseline (fresh) after refrigeration and freezing, n = 39.
| Time from Draw to Analysis 1 | pH 1 | Concentrations, 1 mmol/L | Mean Difference (95% CI), mmol/L | Percentiles of Difference from Fresh iMg, mmol/L 2 |
|||||
|---|---|---|---|---|---|---|---|---|---|
| Min | 25th | 50th | 75th | Max | |||||
| iMg (normalized) | |||||||||
| Fresh 3 | 4.8 min (3.4) | 7.38 (0.03) | 0.54 (0.05) | Reference | - | - | - | - | - |
| Refrigerated | 69.6 min (25.3) | 7.45 (0.04) | 0.68 (0.04) | 0.14 (0.12,0.16) | 0.07 | 0.10 | 0.13 | 0.17 | 0.31 |
| Frozen | 82.2 days (15.4) | 7.51 (0.04) | 0.73 (0.05) | 0.19 (0.18,0.21) | 0.11 | 0.15 | 0.19 | 0.25 | 0.29 |
| iMg (not normalized) | |||||||||
| Fresh | 4.8 min (3.4) | 7.38 (0.03) | 0.54 (0.05) | Reference | - | - | - | - | - |
| Refrigerated | 69.6 min (25.3) | 7.45 (0.04) | 0.65 (0.04) | 0.11 (0.10,0.13) | 0.04 | 0.07 | 0.09 | 0.13 | 0.25 |
| Frozen | 82.2 days (15.4) | 7.51 (0.04) | 0.68 (0.05) | 0.14 (0.12,0.15) | 0.05 | 0.09 | 0.13 | 0.18 | 0.20 |
1 Mean (standard deviation); 2 the distribution (in percentiles) of the difference between refrigerated vs. fresh and frozen vs. fresh. A value of 0 indicates that the iMg measured in refrigerated (or frozen) and fresh were identical. 3 Refrigerated and frozen blood samples were measured in serum, while fresh was measured in whole blood.