Circulating natriuretic peptide levels in acute heart failure.

Natriuretic peptide (NPs) levels have achieved worldwide acceptance. They are excellent rule-in and rule-out biomarkers for patients presenting with dyspnea. In the hospital, NP levels may represent altered forms of B-type natriuretic peptide (BNP), including the inactive precursor molecule, pro-BNP. NP levels drop during hospitalization as the patient is decongested. In the future, NP levels may be used as a surrogate to titrate outpatient therapy.