Niek Dirks (Presenter)
VU University Medical Center
Bio: During my Bsc and Msc in Farmaceutical Sciences i acquired an interest in mass spectrometry and more specifically ms in a clinical setting. During my internship at the Endocrine Laboratory at the VU University Medical Center I started with small molecules. Since I started my Phd I have funnelled my scientific efforts to proteinhormones instead. As this is a new field I have just entered, I would very much like to see what MSACL will teach me this year.
Authorship: NF Dirks (1), HW Vesper (2), AE van Herwaarden (3), JM van den Ouweland (4), IP Kema (5), JG Krabbe (6) and AC Heijboer (1)
(1) Department of Clinical ChemistryVUmc, Amsterdam(2) CDC, Atlanta, GA (3) Radboud University Medical Centre, Nijmegen (4) Canisius-Wilhelmina Hospital, Nijmegen (5) UMCG, Groningen (6) Medlon Spectrum, Twente
| Short Abstract To assess 25(OH)D standardization in the Netherlands we performed two method comparisons. One with the currently routinely used 25(OH)D LC-MS/MS methods in the Netherlands and the Ghent University reference measurement procedure. The second comparison between all the Dutch methods was conducted in patient samples. Three out of five methods aligned perfectly with both the reference measurement procedure and the median of all methods. One of the routine methods showed a small positive bias, while another showed a small negative bias consistently in both comparisons. These biases most probably originated from differences in calibration procedure and may be obviated by reassessing calibration of stock standards and/or calibrator matrices. |
Long Abstract
Introduction
The variety of LC-MS/MS methods measuring total 25(OH)D used today is vast and despite efforts by various instances to standardize them, results also vary.
Methods
Here we performed a comparison in samples of healthy donors between the currently routinely used 25(OH)D LC-MS/MS methods in the Netherlands and the Ghent University reference measurement procedure to address this issue (n = 40). Furthermore, an interlaboratory comparison in patient serum samples assessed agreement between the Dutch diagnostic methods (n = 37).
Results
The overall correlation of the routine methods for 25(OH)D3 with the reference measurement procedures and with the mean of all diagnostic methods was excellent (r > 0.993 and r > 0.989, respectively). Three out of five methods aligned perfectly with both the reference measurement procedure and the median of all methods. One of the routine methods showed a small positive bias, while another showed a small negative bias consistently in both comparisons.
Discussion
These biases most probably originated from differences in calibration procedure and may be obviated by reassessing calibration of stock standards and/or calibrator matrices. In conclusion, five diagnostic centers have performed a comparison with the 25(OH)D Ghent University reference measurement procedure in healthy donor serum samples and a comparison among themselves in patient serum samples. Both analyses showed a high correlation and specificity of the routine LC-MS/MS methods, yet did reveal some small standardization issues that could not be traced back to the technical details of the different methods. Hence, this study indicates various calibration procedures can result in perfect alignment.
References & Acknowledgements:
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