Methods of determination of activation or inactivation of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) hormonal systems

An in vitro method of determining activation or inactivation of the atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) hormonal systems in a subject, the method comprising detecting in a single reading, in a single assay the combined presence of atrial and brain natriuretic peptide prohormones (proANP and proBNP) or fragments thereof in a sample from the subject, wherein, compared to a reference level, detection of an increase in the combined presence of proANP and proBNP, or fragments thereof, in the sample indicates activation of the ANP and BNP hormonal systems, and wherein, compared to a reference level, detection of a decrease in the combined presence of proANP and proBNP, or fragments thereof, in the sample indicates inactivation of these systems, wherein said method does not comprise detection of the presence of proANP and proBNP or fragments thereof individually;

• wherein detection of activation of the ANP and BNP hormonal systems is diagnostic of cardiac impairment or detection of inactivation of ANP and BNP hormonal systems indicates successful treatment of cardiac impairment.