Optimum blood collection intervals for B-type natriuretic peptide testing in patients with heart failure

Patients with congestive heart failure have increased concentrations of B-type natriuretic peptide (BNP) in blood. We determined the frequency of serial BNP measurements that exceeded the biologic variation of BNP of 100% as a function of days between blood collections. Samples collected 7 days apart were associated with the highest frequency (50%) of statistically different results (increased or decreased) compared with daily collections, where increased or decreased results occurred less often (22%).