Cardiac Natriuretic Hormones as Markers of Cardiovascular Disease: Methodological Aspects

Abstract

Cardiac natriuretic hormones (CNH) constitute a complex family of related peptides with similar peptide chains as well as degradation pathways (see Chap. 3 for more details). CNH derive from common precursors, pre-pro-hormones (i.e., preproANP and preproBNP). Pro-hormone peptides are further split into an inactive longer NT-proANP or NTproBNP and the biologically active hormones, ANP or BNP, which are secreted in the blood in equimolar amounts. However, ANP and BNP have a shorter plasma half-life and consequently lower plasma concentrations compared to NT-proANP and NT-proBNP (Table 4.1). For these reasons, setting up an immunoassay for N-terminal peptide fragments of proANP and proBNP should be easier than that for ANP and BNP, because the requested analytical sensitivity is not too low [1]. However, immunoassays for NTproANP and NTproBNP may be affected by problems related to the different assay specificities: as shown in Table 4.1, different results are produced by different methods with a large bias [1, 2, 3]. The different analytical performances could have some relevance in the diagnostic accuracy of different assay methods in discriminating between subjects with or without cardiac disease [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11].