Atrial natriuretic peptide levels in the elderly: differentiating normal aging changes from disease.

BACKGROUND: Atrial natriuretic peptide (ANP) levels increase with advancing age and in patients with cardiac dysfunction. Previous studies have failed to differentiate the elevated ANP levels of normal aging from those of cardiac disease.
METHODS: To differentiate the increased ANP levels seen in normal aging from that of disease, fasting supine ANP was measured in healthy young (n = 24), healthy old (n = 90), and clinically stable but cardiovascularly diseased old (n = 269) residents of a life care facility. ANP levels were correlated with physical exam findings, blood chemistries, measures of physical and cognitive function, and medications.
RESULTS: ANP levels were almost fourfold higher in the healthy elderly than in the young (11.4 +/- 1.1 (SEM) vs 3 +/- 0.3 pmol/L, p < .01), and two-and-one-half times higher in the cardiovascular-diseased elderly than the healthy elderly (29 +/- 1.9 vs 11.4 +/- 1.1 pmol/L, p < .01). An ANP value of 21 pmol/L has a sensitivity of 83% and specificity of 52% in distinguishing those elders classified as healthy from those classified as having chronic cardiovascular disease. ANP levels had positive univariate correlation with age (even from 70 to 102 years) and systolic blood pressure. ANP rose progressively with increasing numbers of markers of cardiovascular comorbidity. ANP was higher in subjects with jugular venous pressure > 10 cm, presence of a third heart sound, peripheral edema, artificial cardiac pacemaker, atrial arrhythmias, and in those taking digoxin, diuretics, or nitrates. On multivariate analysis independent predictors of ANP levels were, in descending order, nitrates, age, diuretics, and atrial arrhythmias.
CONCLUSION: These data suggest that ANP levels greater than 21 pmol/L are associated with cardiovascular comorbidity in a clinically stable elderly cohort.