Inflammation increases NT-proBNP and the NT-proBNP/BNP ratio.

Plasma BNP and NT-proBNP are often regarded as interchangeable parameters in assessing heart failure (HF) severity and prognosis. Renal failure results in disproportionate increases of NT-proBNP and an increased NT-proBNP/BNP ratio. Low kidney function is therefore considered particularly when NT-proBNP is used to assess HF. The purpose of this study was to identify other conditions affecting the NT-proBNP/BNP ratio. We examined the NT-proBNP/BNP ratio, 26 other lab parameters, and clinical factors in 218 patients admitted to the HF ward. In addition to renal function, we also found significant correlations between the NT-proBNP/BNP ratio and inflammation as measured by orosomucoid (r = 0.525, p < 0.0001), CRP (r = 0.333, p < 0.0001), haptoglobulin (r = 0.201, p = 0.02), and alpha1-antitrypsin (r = 0.223, p = 0.01). Reverse correlation was found with transferrin (r = -0.323, p < 0.0001), albumin (r = -0.251, p = 0.003), and S-Fe (r = -0.205, p = 0.02), parameters known to decrease during inflammation. Inflammation increased levels of NT-proBNP more than BNP, resulting in an increased NT-proBNP/BNP ratio. Our findings indicate that NT-proBNP should be evaluated concomitantly with inflammatory status to avoid overestimation of HF severity.