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Measurement of Circulating 1,25-Dihydroxyvitamin D: Comparison of an Automated Method with a Liquid Chromatography Tandem Mass Spectrometry Method.

Zittermann A, Ernst JB, Becker T, Dreier J, Knabbe C, Gummert JF, Kuhn J - Int J Anal Chem (2016)

Bottom Line: Background.In 129 clinical samples, we compared a new automated assay with a commercially available liquid chromatography tandem mass spectrometry (LC-MS/MS) kit.Results.

View Article: PubMed Central - PubMed

Affiliation: Clinic for Thoracic and Cardiovascular Surgery, Heart and Diabetes Center North Rhine-Westphalia, Ruhr University Bochum, 32545 Bad Oeynhausen, Germany.

ABSTRACT
Background. The clinical relevance of circulating 1,25-dihydroxyvitamin D (1,25(OH)2D) is probably underappreciated, but variations in the measurement of this difficult analyte between different methods limit comparison of results. Methods. In 129 clinical samples, we compared a new automated assay with a commercially available liquid chromatography tandem mass spectrometry (LC-MS/MS) kit. Results. Median (interquartile range) 1,25(OH)2D concentrations with the automated assay and the LC-MS/MS method were 26.6 pg/mL (18.5-39.0 pg/mL) and 23.6 pg/mL (16.1-31.3 pg/mL), respectively (P = 0.001). Using the method-specific cut-offs for deficient 1,25(OH)2D levels (<20 pg/mL for the automated assay and <17 pg/mL for the LC-MS/MS method), the percentage of patients classified as 1,25(OH)2D deficient was 28.7% and 27.1%, respectively. However, concordance between the two methods for deficient levels was only 62% and the concordance correlation coefficient was poor (0.534). The regression equation resulted in an intercept of -1.99 (95% CI: -7.33-1.31) and a slope of 1.27 (95% CI: 1.04-1.52) for the automated assay. The mean bias with respect to the mean of the two methods was -3.8 (1.96 SD: -28.3-20.8) pg/mL for the LC-MS/MS method minus the automated assay. Conclusions. The two methods show only modest correlation and further standardization is required to improve reliability and comparability of 1,25(OH)2D test procedures.

No MeSH data available.


Related in: MedlinePlus

Ogive showing the percentage of specimen with 1,25-dihydroxyvitamin D concentrations below a certain value according to test procedure. The vertical lines mark different cut-off levels for deficient or harmful 1,25-dihydroxyvitamin D concentrations.
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fig2: Ogive showing the percentage of specimen with 1,25-dihydroxyvitamin D concentrations below a certain value according to test procedure. The vertical lines mark different cut-off levels for deficient or harmful 1,25-dihydroxyvitamin D concentrations.

Mentions: Figure 2 shows the percentages of patients below a certain 1,25(OH)2D threshold. Using a value of <20 pg/mL as the cut-off for deficient 1,25(OH)2D levels, the percentages of patients classified as 1,25(OH)2D deficient with the automated assay and the LC-MS/MS method were 28.7% and 36.4%, respectively. However, if the method-specific cut-offs were used (<20 pg/mL for the automated assay and <17 pg/mL for the LC-MS/MS method), the percentages of patients classified as 1,25(OH)2D deficient were 28.7% and 27.1% and were thus almost identical for both methods. None of the samples had 1,25(OH)2D concentrations above 80 pg/mL. If the method-specific upper limit of the reference range was used, the percentage of patients classified as having high 1,25(OH)2D levels was 0% with the automated assay (>79 pg/mL) and 3.1% (>53 pg/mL) with the LC-MS/MS method. However, concordance for the automated method and LC-MS/MS for deficient levels (<20 pg/mL and <17 pg/mL, resp.) was only 62% (38% were deficient according to the automated assay but normal according to the LC-MS/MS method). Concordance for the automated method and LC-MS/MS for adequate levels (20 to 79 pg/mL and 17 to 53 pg/mL, resp.) was 86%.


Measurement of Circulating 1,25-Dihydroxyvitamin D: Comparison of an Automated Method with a Liquid Chromatography Tandem Mass Spectrometry Method.

Zittermann A, Ernst JB, Becker T, Dreier J, Knabbe C, Gummert JF, Kuhn J - Int J Anal Chem (2016)

Ogive showing the percentage of specimen with 1,25-dihydroxyvitamin D concentrations below a certain value according to test procedure. The vertical lines mark different cut-off levels for deficient or harmful 1,25-dihydroxyvitamin D concentrations.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4835639&req=5

fig2: Ogive showing the percentage of specimen with 1,25-dihydroxyvitamin D concentrations below a certain value according to test procedure. The vertical lines mark different cut-off levels for deficient or harmful 1,25-dihydroxyvitamin D concentrations.
Mentions: Figure 2 shows the percentages of patients below a certain 1,25(OH)2D threshold. Using a value of <20 pg/mL as the cut-off for deficient 1,25(OH)2D levels, the percentages of patients classified as 1,25(OH)2D deficient with the automated assay and the LC-MS/MS method were 28.7% and 36.4%, respectively. However, if the method-specific cut-offs were used (<20 pg/mL for the automated assay and <17 pg/mL for the LC-MS/MS method), the percentages of patients classified as 1,25(OH)2D deficient were 28.7% and 27.1% and were thus almost identical for both methods. None of the samples had 1,25(OH)2D concentrations above 80 pg/mL. If the method-specific upper limit of the reference range was used, the percentage of patients classified as having high 1,25(OH)2D levels was 0% with the automated assay (>79 pg/mL) and 3.1% (>53 pg/mL) with the LC-MS/MS method. However, concordance for the automated method and LC-MS/MS for deficient levels (<20 pg/mL and <17 pg/mL, resp.) was only 62% (38% were deficient according to the automated assay but normal according to the LC-MS/MS method). Concordance for the automated method and LC-MS/MS for adequate levels (20 to 79 pg/mL and 17 to 53 pg/mL, resp.) was 86%.

Bottom Line: Background.In 129 clinical samples, we compared a new automated assay with a commercially available liquid chromatography tandem mass spectrometry (LC-MS/MS) kit.Results.

View Article: PubMed Central - PubMed

Affiliation: Clinic for Thoracic and Cardiovascular Surgery, Heart and Diabetes Center North Rhine-Westphalia, Ruhr University Bochum, 32545 Bad Oeynhausen, Germany.

ABSTRACT
Background. The clinical relevance of circulating 1,25-dihydroxyvitamin D (1,25(OH)2D) is probably underappreciated, but variations in the measurement of this difficult analyte between different methods limit comparison of results. Methods. In 129 clinical samples, we compared a new automated assay with a commercially available liquid chromatography tandem mass spectrometry (LC-MS/MS) kit. Results. Median (interquartile range) 1,25(OH)2D concentrations with the automated assay and the LC-MS/MS method were 26.6 pg/mL (18.5-39.0 pg/mL) and 23.6 pg/mL (16.1-31.3 pg/mL), respectively (P = 0.001). Using the method-specific cut-offs for deficient 1,25(OH)2D levels (<20 pg/mL for the automated assay and <17 pg/mL for the LC-MS/MS method), the percentage of patients classified as 1,25(OH)2D deficient was 28.7% and 27.1%, respectively. However, concordance between the two methods for deficient levels was only 62% and the concordance correlation coefficient was poor (0.534). The regression equation resulted in an intercept of -1.99 (95% CI: -7.33-1.31) and a slope of 1.27 (95% CI: 1.04-1.52) for the automated assay. The mean bias with respect to the mean of the two methods was -3.8 (1.96 SD: -28.3-20.8) pg/mL for the LC-MS/MS method minus the automated assay. Conclusions. The two methods show only modest correlation and further standardization is required to improve reliability and comparability of 1,25(OH)2D test procedures.

No MeSH data available.


Related in: MedlinePlus