Table 1.
Baseline characteristics
| Clinical or Biochemical Endpoints | VIT-D (n=40) | PBO (n=50) | P Value |
|---|---|---|---|
| Age (years)a | 26 (23, 32) | 27 (22, 39) | 0.82 |
| Sex (number) | 0.85 | ||
| male | 16 | 19 | |
| female | 24 | 31 | |
| Season enrolled (number) | 0.80 | ||
| fall | 15 | 14 | |
| spring | 8 | 12 | |
| summer | 10 | 15 | |
| winter | 7 | 9 | |
| Ethnicity (number) | 0.29 | ||
| non-Hispanic | 38 | 44 | |
| Hispanic | 2 | 6 | |
| Race (number) | 0.15 | ||
| white/Caucasian | 18 | 20 | |
| black/African-American | 8 | 18 | |
| Asian | 11 | 6 | |
| multiple races/other | 3 | 6 | |
| BMI (kg/m2) | 25±4 | 26±7 | 0.46 |
| MVI use | 0.46 | ||
| takes MVI | 5 | 3 | |
| does not take MVI | 35 | 47 | |
| Total VIT-D intake (international units)a | 150 (75, 231) | 65 (31, 130) | 0.01 |
| from fooda | 100 (71, 200) | 64 (31, 117) | 0.01 |
| from supplementsa | 0 (0, 43) | 0 (0, 0) | 0.06 |
| Total calcium intake (mg) | 1162±651 | 939±523 | 0.08 |
| 25OHD (ng/ml) by CLIAb | 13±3 | 15±4 | 0.54 |
| 25OHD (ng/ml) by LC/MS/MSc | 18±7 | 18±7 | 0.83 |
| 25OHD levels by LC/MS/MS | 0.17 | ||
| 25OHD ≤20 ng/mlc (n) | 25 | 35 | |
| 25OHD >20 to ≤30 ng/mlc (n) | 15 | 12 | |
| 25OHD >30 ng/mlc (n) | 0 | 3 | |
| FGF23 (pg/ml) | 43±17 | 39±29 | 0.38 |
| PTH (pg/ml) | 42±15 | 42±16 | 0.76 |
| 1,25(OH)2D (pg/ml) | 42±17 | 42±13 | 0.97 |
| Calcium (mg/dl) | 9.1±0.4 | 9.0±0.4 | 0.35 |
| Phosphate (mg/dl) | 3.3±0.5 | 3.3±0.4 | 0.88 |
| Creatinine (mg/dl) | 0.9±0.1 | 0.9±0.2 | 0.28 |
| Creatinine clearance (ml/min) | 116±29 | 112±37 | 0.53 |
| Creatinine clearance (ml/min per 1.73m2) | 97±17 | 95±17 | 0.60 |
| FePO4 (%) | 11±5 | 13±6 | 0.10 |
Values are presented as mean ± SD unless otherwise indicated. VIT-D, vitamin D; PBO, placebo; BMI, body mass index; MVI, multivitamin; 25OHD, 25-hydroxyvitamin D; CLIA, chemiluminescent immunoassay; LC/MS/MS, liquid chromatography/tandem mass spectroscopy; FGF23, fibroblast growth factor 23; PTH, parathyroid hormone; 1,25(OH)2D, 1,25-dihydroxyvitamin D; FePO4, fractional excretion of phosphate. Systeme International conversion factors: 25OHD (nM), 2.496; PTH (ng/L), 1; 1,25(OH)2D (pmol/L), 2.6; calcium (mM), 0.2495; phosphate (mM), 0.3229; and creatinine (mM), 88.4.
Age and vitamin D intake are presented as median (25th percentile, 75th percentile).
The 25OHD by CLIA was performed at screening.
The 25OHD by LC/MS/MS, similar to the other biochemical data, was performed at week 0 or baseline.