InChristAlone
Member
So since I am not sure what immunoassay labcorp is doing then getting the LC-MS/MS is probably the best bet?Here is a recent study on the subject, some performed better than others.
View attachment 31124
4. Conclusions
All 13 assays achieved the VDSP criterion of %CV ≤ 10 % while only 9 assays satisfied the criterion of ≤ ±5 % mean bias (i.e., Abbott, BeckmanCoulter,Biom ́erieuxI,DiaSorin,Diazyme,FujirebioInc., Roche, Siemens, and LC–MS/MS). However, 3 of the 9 assays meeting the bias criterion had only 16 %–24 % of the individual measurements within ±5 % bias indicating a potential need to strengthen the VDSP bias criterion. The presence of a significant number of single-donor samples with high levels of 25(OH)D2 in this study provided a critical performance test for these assays with ten immunoassays exhibiting some change in response due to the high 25(OH)D2 concentration samples with the Abbott, Biom ́erieux, and DIAsource assays having the largest deviations (25 %–38 %). Two immunoassays (Fujirebio Inc. and Beckman Coulter) and the LC–MS/MS assay were only minimally affected by the presence of the high 25(OH)D2 concentration samples. One interpretation of these deviations with high 25(OH)D2 concentration samples would be that some assays do not have equal response or recovery for both 25(OH)D2 and 25(OH)D3. For the 12 immunoassays, the Fujirebio Inc. assay exhibited the lowest %CV and the highest percentage of individual measurements within ±5 % mean bias. Expanded assay performance evaluation and comparison with 34 additional assays used in multiple laboratories Intercomparison Study 2 are detailed elsewhere [31,32].
Vitamin D Standardization Program (VDSP) intralaboratory study for the assessment of 25-hydroxyvitamin D assay variability and bias
An intralaboratory study assessing assay variability and bias for determination of serum total 25-hydroxyvitamin D [25(OH)D] was conducted by the Vita…www.sciencedirect.com