Brain natriuretic peptide increases in septic patients without severe sepsis or shock.

Background: B-type natriuretic peptide (BNP) production increases in critically ill septic patients. We assessed the hypothesis that BNP is elevated in patients with community-acquired infections without severe sepsis or septic shock.

Methods: We studied 54 patients [20 males, median age 39 (interquartile range 23, 71)] without heart disease, persistent arrhythmias, or renal failure. BNP was measured in all patients at hospital admission and at pre-discharge and in a control group of 52 individuals. Myoglobin levels were also measured in septic patients.

Results: The infection was microbial in 40 patients, viral in 11, and of undefined etiology in 3. A systemic inflammatory response was evident in 38 patients on the initial evaluation. BNP on admission was higher in patients than in controls [25 (10, 82) pg/ml vs. 13 (5, 30) pg/ml, p=0.01] and it decreased to 16 (5, 47) pg/ml pre-discharge (p=0.0002). Multiple logistic regression identified the presence of microbial infection as the only independent predictor of an elevated BNP value on admission [adjusted odds ratio 9.8 (1.02-93.8), p=0.04]. In patients with microbial infection, location of infection in the lower respiratory tract and the presence of diabetes mellitus were independent predictors of the magnitude of BNP increase. Myoglobin was also increased on hospital admission 80 (37, 231) ng/ml and decreased pre-discharge to 59 (38, 94) ng/ml, p=0.004. Myoglobin level changes from admission to discharge were more prominent with increasing age and in females.

Conclusion: BNP levels are elevated in the acute phase of community-acquired microbial infections without severe sepsis or septic shock.