The quantification of total 25-OH vitamin D (25-OH D) in blood is the most reliable marker for the vitamin D status in a patient. The “gold standard” method to quantify 25-OH D is the tandem mass LC-MS/MS from the University of Ghent and the NIST. Today, there is a significant number of chemiluminescent tests available on the market for this parameter. Differences between them include the method to separate 25-OH D from its binding protein, the cross-reactivity and the specificity of the antibody. Our laboratory has a lot of experience in 25-OH D quantification and we have always tried to work with the method closest in line with the gold standard. For this reason, we decided to evaluate the new immunoassay Lumipulse® G 25-OH Vitamin D assay on the LUMIPULSE G1200 (Fujirebio), the only sandwich method existing on the market and with a novel method to separate the VDBP, not by thermic or chemical effect, but by substitution.
We tested 1000 samples, randomly chosen, among the ones analysed in the Clinical Chemistry laboratory of the hospital Fundación Jiménez Díaz. 25-OH D levels were quantified with the following analysers: ADVIA Centaur XP (Siemens), through a competitive immunoassay, and LUMIPULSE G1200 (Fujirebio), through a two-step dilution sandwich method. Fifty of these samples (the most discordant ones in each clinical group) were also evaluated with a VDSP traceable LC-MS/MS (Dr. Cavalier, Liège).
After the evaluation, results show:
- There is a good correlation between both methods, with Lumipulse values approximately 10% higher than Centaur values
- When comparing both methods with a VDSP-traceable LC-MS/MS, the Lumipulse G 25-OH Vitamin D assay showed a higher correlation and less dispersion than the ADVIA Centaur XP (Siemens) Vitamin D Total assay.
After our evaluation we can say that the Lumipulse G 25-OH Vitamin D reagent (Fujirebio) shows a very strong correlation with a VDSP-traceable LC-MS/MS (Dr. Cavalier, Liège) and is fully recommended for the 25-OH D quantification.
Besides the good quality of the reagent, an additional advantage of the LUMIPULSE G1200 is that the system was very easy to learn and use and very intuitive, as well as extremely reproducible.
Isabel Alonso, Blanca Torrubia and Concha de la Piedra
Laboratorio de Bioquímica - Fundación Jiménez Díaz - Madrid - Spain
Alonso, A., Torrubia, B., López Ramiro, E., Mahillo, I., de la Piedra, C. (2015). Comparison between two quimioluminiscent automated assays for the 25-OH-vitamin D quantification. SEIOMM Congress, Bilbao, Spain, 2015. Available at: http://seiomm.org/portfolio/posters-xx-congreso-seiomm-2015-bilbao