Two-site evaluation of the Roche Elecsys Vitamin D total III assay

Abstract

Objectives The high request for vitamin D testing in the last decades has led manufacturers to develop assays on automated immunoassay platforms. The objective of this study was to evaluate the performance of the new Elecsys Vitamin D total III assay for the measurement of total 25(OH)D. Methods A total of 844 serum samples collected in two clinical laboratories were used to evaluate the new Roche Elecsys Vitamin D total III assay. Comparisons with Roche Elecsys Vitamin D total II and liquid chromatography tandem mass spectrometry (LC-MS/MS) were carried out. Additionally, assay imprecision, linearity, matrix effects, biotin interference, cross-reactivity with 24,25(OH)2D3 and 3-epi-25(OH)D3, and outlier rate were evaluated for the Elecsys Vitamin D total III assay. Results Only the comparison between LC-MS/MS and Roche Elecsys Vitamin D total III achieved the optimal specification for bias (i.e., <3.4%). Imprecision, linearity and matrix effects showed acceptable results. The biotin interference threshold was increased up to 1,200 ng/mL and the outlier rate was low (0.26%). The cross-reactivity with 24,25(OH)2D3 and 3-epi-25(OH)D3 was weak or modest in available patient samples. However, using SRM972a with a high level of 3-epi-25(OH)D3 (enriched) revealed an important cross-reactivity with both Roche Elecsys Vitamin D total II and III assays (+74.7% and +73.7%). Conclusions In conclusion, the Roche Elecsys Vitamin D total III assay presents several advantages compared to the previous assay generation: higher biotin interference threshold, broader measuring range, and better comparability with LC-MS/MS. However, the cross-reactivity toward 3-epi-25(OH)D3 is still problematic in high titer samples.

Relevanz der Vitamin D-Messung in der Patientenbetreuung

“…Weiterhin sind Methoden, die mit biotinilierten Reagenzien arbeiten, anfällig für eine Beeinflussung durch von Patienten eingenommene Biotinhaltige Nahrungsergänzungsmittel (teilweise werden für die Stimulation des Haarwuchses hohe Dosen verwendet) 10 .…”

“…Spezifischer erfolgt die Messung mittels LC-MS/MS-Methoden, die keine Kreuzreaktion mit 24,25-dihydroxyvitamin aufweisen. Jedoch kann bei den LC-MS/MS-Methoden das 3-epi-25-OH-Vitamin D die Messung stören aufgrund des identischen Verhältnisses von Masse zu Ladung 10 13 . Wegen des erhöhten Aufwandes werden LC-MS/MS -Methoden in der Routine -Diagnostik nicht häufig eingesetzt.…”