Natriuretic peptides have proved useful in the diagnosis of heart failure in patients presenting to the emergency department with shortness of breath. Dyspnea and orthopnea in heart failure are clinical expressions of pulmonary capillary congestion and leakage, which may be assessed by the percentage of pulmonary hemosiderin-laden macrophages (HLM) in induced sputum. We found a significant difference in the percentage of HLM present in sputum among patients with acute heart failure, patients with noncardiac dyspnea with ventricular dysfunction, and patients without heart failure (p = 0.008). N-terminal pro-brain natriuretic peptide (N-BNP) concentrations were also different among these 3 patient groups (p = 0.006). N-BNP concentrations were positively associated with the percentage of HLM in patients with acute dyspnea (r = 0.6; p <0.0001). N-BNP, in addition to being a ventricular dysfunction marker, may reflect the severity of pulmonary capillary congestion and leakage in patients with acute shortness of breath. © 2004 Excerpta Medica Inc.