L. SALEH¹, D. MUELLER¹, A. VON ECKARDSTEIN<sup>1

1</sup>Institute of Clinical Chemistry, University Hospital of Zurich and University of Zurich, Zurich, Switzerland

Methods: Total 25 hydroxy vitamin D (25(OH)D) levels were measured in 100 selected serum samples from our routine analysis with Lumipulse® G 25-OH Vitamin D assay. The results were compared with those obtained with LC-MS/MS and 3 other automated 25(OH)D assays (Roche Vitamin D total assay, Beckman 25(OH) VITAMIN D TOTAL assay and Abbott 25-OH Vitamin D assay). The accuracy of each assay tested was evaluated against a certified reference serum panel for 25(OH) D (Ref!25OHD)

Results: Inter-and intra-impression of the Lumipulse® G vitamin D assay was <5% for quality control samples.
Lumipulse® G 25-OH Vitamin D assay showed the highest correlation among the assays tested to the LC-MS/MS method (r = 0.986). The mean relative bias obtained was -15.6% (Lumipulse® G), -12.7% (Beckmann), -2.1% (Abbott) and 9.7% (Roche) as compared to LC-MS/MS method. Comparison with the certified reference patient panel yielded a mean relative bias of -12.9% (Lumipulse® G) for total 25(OH)D (sum of 25(OH)D2 and 25(OH)D3).
Compared to LC-MS/MS, sensitivity of different methods in detecting vitamin D deficiency (<20 ng/mL) varied from 100% for the Lumipulse® G 25-OH Vitamin D assay to 72.7% for Roche, and specificity ranged from 94.4% for Roche to 87.6% for Beckman.

Conclusion: The Lumipulse® G vitamin D assay demonstrated a good correlation with the LC-MS/MS method. The performance of the assay is well-suited for routine 25(OH)D measurement in clinical serum samples.