Influence of Vitamin D Binding Protein on Accuracy of 25-Hydroxyvitamin D Measurement Using the ADVIA Centaur Vitamin D Total Assay

Table 4

Mean bias (±SD) compared to LC-MS/MS for the low, medium, and high range DBP groups for combined populations and each population separately: healthy and DBP-spiked, DBP-spiked, pregnant women, and dialysis patients.

	DBP; ≤136 μg/mL	DBP; 137–559 μg/mL	DBP; ≥560 μg/mL
Bias (ng/mL)
Combined populations	1.67 ± 3.33; (n = 24)	−0.45 ± 3.07; (n = 57)	−3.0 ± 3.98; (n = 25)
Healthy (endogenous and endogenous + spiked)		−2.78 ± 2.12; (n = 18)	−1.88 ± 2.47; (n = 12)
Healthy (endogenous + spiked)		−0.45 ± 2.40; (n = 13)	−1.88 ± 2.47; (n = 12)
Pregnancy	0.017 ± 2.76; n = 6	−0.72 ± 0.13; (n = 18)	−4.72 ± 3.67; (n = 12)
Dialysis	2.23 ± 3.38; (n = 18)	−0.38 ± 3.91; (n = 21)	2.30; (n = 1)
% bias
Combined populations	8.0 ± 10.99%; (n = 24)	−1.0 ± 10.66%; (n = 57)	−8.0 ± 10.09%; (n = 25)
Healthy (endogenous and endogenous + spiked)		0.0 ± 5.30%; (n = 18)	−3.0 ± 3.98%; (n = 12)
Healthy (endogenous + spiked)		0.0 ± 6.10%; (n = 13)	−3.0% ± 3.98%; (n = 12)
Pregnancy	2.0 ± 10.9%; (n = 6)	−3.0 ± 12.6%; (n = 18)	−14.0 ± 9.9%; (n = 12)
Dialysis	10.0 ± 10.6%; (n = 18)	0.0 ± 12.4%; (n = 21)	12.0%; (n = 1)

DBP: vitamin D binding protein. To convert 25(OH)D concentrations to nanomoles per liter (nmol/L), multiply by 2.5.