TABLE 2.
Plasma 25(OH)D concentrations and number (%) meeting 25(OH)D cutoffs of ≥50 and ≥75 nmol/L in infants that received 10 μg/d of D2 or D3 as assessed by immunoassay and LC-MS/MS1
| Treatments |
||||
| D2 | n | D3 | n | |
| Immunoassay | ||||
| Baseline 25(OH)D, nmol/L | 56.9 ± 33.7 | 25 | 69.5 ± 30.6 | 26 |
| Follow-up 25(OH)D, nmol/L | 69.0 ± 30.0 | 24 | 82.9 ± 23.1 | 26 |
| Δ Total 25(OH)D, nmol/L | 7.1 ± 36.7 | 23 | 13.4 ± 19.6 | 26 |
| (95% CI) | −8.8–22.9 | 5.5–21.4 | ||
| LC-MS/MS2 | ||||
| Baseline 25(OH)D3, nmol/L | 44.2 ± 23.8 | 26 | 54.6 ± 23.7 | 26 |
| Baseline 25(OH)D3, n (%) | ||||
| ≤24.9 nmol/L | 8 (30.8) | 4 (15.4) | ||
| 25–49.9 nmol/L | 5 (19.2) | 6 (23.1) | ||
| 50–74.9 nmol/L | 12 (46.2) | 13 (50.0) | ||
| ≥75 nmol/L | 1 (3.9) | 3 (11.5) | ||
| Follow-up | ||||
| Total 25(OH)D, nmol/L | 64.8 ± 26.2 | 24 | 76.8 ± 17.4 | 26 |
| Follow-up 25(OH)D2, nmol/L | 45.1 ± 30.7 | na | ||
| Follow-up 25(OH)D3, nmol/L | 19.6 ± 20.2 | 76.8 ± 17.4 | ||
| Δ Total 25(OH)D,2 nmol/L | 17.6 ± 26.7 | 24 | 22.2 ± 20.2 | 26 |
| (95% CI) | 6.4–28.9 | 14.0–30.3 | ||
| 25(OH)D ≥50 nmol/L at follow-up,3 n (%) | 18 (75.0) | 25 (96.2)* | ||
| 25(OH)D ≥75 nmol/L at follow-up,3 n (%) | 9 (37.5) | 14 (53.8) | ||
1
Values are frequency and percent or mean ± SD. *Different from D2 group, P ≤ 0.05. D2, ergocalciferol; D3, cholecalciferol; LC-MS/MS: liquid chromatography tandem MS; 25(OH)D, 25-hydroxyvitamin D; 25(OH)D3, 25-hydroxycholecalciferol; 25(OH)D2, 25-hydroxyergocalciferol.
2
D2 group: total 25(OH)D = 25(OH)D2 + 25(OH)D3; D3 group: 25(OH)D3.
3
Results were similar to LC-MS/MS when tested by immunoassay: proportion of infants ≥50 nmol (D2: 79.2% vs. D3: 100%) or ≥75 nmol (D2: 37.5% vs. D3: 57.7%) cutoffs. 1 g vitamin D = 40 iu.