A candidate liquid chromatography mass spectrometry reference method for the quantification of the cardiac marker 1-32 B-type natriuretic peptide

Abstract

Background: B-type natriuretic peptide (BNP) is a 32 amino acid cardiac hormone routinely measured by immunoassays to diagnose heart failure. While it is reported that immunoassay results can vary up to 45%, no attempt of standardization and/or harmonization through the development of certified reference materials (CRMs) or reference measurement procedures (RMPs) has yet been carried out. Methods: B-type natriuretic peptide primary calibrator was quantified traceably to the International System of Units (SI) by both amino acid analysis and tryptic digestion. A method for the stabilization of BNP in plasma followed by protein precipitation, solid phase extraction (SPE) and liquid chromatography (LC) mass spectrometry (MS) was then developed and validated for the quantification of BNP at clinically relevant concentrations (15-150 fmol/g). Results: The candidate reference method was applied to the quantification of BNP in a number of samples from the UK NEQAS Cardiac Markers Scheme to demonstrate its applicability to generate reference values and to preliminary evaluate the commutability of a potential CRM. The

Analytical barriers in clinical B-type natriuretic peptide measurement and the promising analytical methods based on mass spectrometry technology

“…Quantification accuracy is usually dependent on the quality and uncertainty of internal and external standards. Torma et al [25] developed a method of SI-traceable quantification for reference material preparation. During this work, synthetic BNP was quantified at the amino acid and peptide levels, which were obtained from hydrolyzed by hydrochloric acid or enzymatically digested by trypsin.…”

“…LGC has published works related to the development of the BNP reference quantitative MS method [25]. Once a BNP 1-32 purity reference material is developed, it can provide a standard value for instrument calibration.…”

“…The poor harmonization in BNP testing was caused by many factors, such as heterogeneity in the analytical methods, systematic error in immunoassays and quality attributes of the diagnostic reagents. Because BNP standardization has not been carried out or is still in the early stages worldwide, it has been difficult to elucidate the problem until now [25]. However, cross-reaction is an undisputed clinical problem [17,18,26,27].…”

Mass spectrometry or immunoassay: est modus in rebus

“…Several papers in this issue of Clinical Chemistry and Laboratory Medicine emphasize the wide range of applications of MS based methods [23][24][25][26][27][28][29][30]. The review by El-Najjar et al [23] highlights the crucial role of TDM of antibiotics in cancer patients: immunoassays are not available for all the classes of these drugs due to the difficulty in β-lactams ring reactivity or degradation.…”

“…The study by Spanaus et al [29] serves as an example of differences in immunoassay performances, thus stressing the importance of evaluating each specific assay: results obtained on comparing two automated immunoassays for the measurement of 1,25 dihydroxyvitamin D with LC-MS/MS demonstrated that one immunoassay is appropriate for clinical purposes in view of its high sensitivity, low imprecision, broad measurement range and agreement with LC-MS/MS. Torma et al [30] developed a cRMP for 1-32 BNP with the potential to support external quality assessment schemes and to establish the bias of immunoassays, in order to enhance harmonization between results.…”