Table 3.
Measured vitamin D-binding protein (DBP) and estimated concentrations of free and bioavailable 25OHD in black versus white participants according to DBP assay method
| Assay Method | DBP ug/ml Median (IQR) N = 119a |
Free 25OHD pg/ml Median (IQR) N = 63b |
Bioavailable 25OHD ng/ml Median (IQR) N = 63b |
|||
|---|---|---|---|---|---|---|
| Black | White | Black | White | Black | White | |
| LC-MS/MS | 261.1 (230.7, 286.8) | 249.5 (230.3, 278.4) | 4.0 (2.9, 6.8) | 10.6 (6.7, 14.0) | 1.8 (1.1, 2.7) | 4.1 (2.2, 5.1) |
| P valuec | 0.24 | <0.0001 | 0.0001 | |||
| Monoclonal ELISA | 105.9 (90.7, 202.7) | 215.4 (169.7, 273.5) | 8.4 (5.8, 17.1) | 10.9 (6.2, 15.0) | 3.4 (2.6, 6.8) | 4.3 (2.1, 6.4) |
| P value | <0.0001 | 0.98 | 0.88 | |||
| Polyclonal ELISA | 379.9 (341.4, 417.5) | 375.8 (333.3, 425.1) | 3.6 (1.9, 4.6) | 6.9 (4.5, 9.5) | 1.3 (0.8, 1.7) | 2.8 (1.5, 3.5) |
| P value | 0.95 | 0.0003 | 0.0007 | |||
a
Analysis limited to participants of black or white race.
b
Analysis limited to homozygous participants of black or white race.
c
Group differences assessed using Student’s t-test or Wilcoxon rank sum test as appropriate.