Blood haemoglobin is an independent predictor of B-type natriuretic peptide (BNP)

BNP (B-type natriuretic peptide) and anaemia are both associated with adverse outcome in patients with chronic heart failure. Whether low haemoglobin levels are independently predictive of elevated BNP levels in subjects without heart failure is unknown. In the present study, we examined the relationship between haemoglobin and BNP levels in 234 patients with suspected coronary heart disease without a history of chronic heart failure, adjusting for known predictors of BNP levels. By univariate analysis, haemoglobin levels were inversely related to logarithmically transformed BNP values (r=−0.30, P<0.0001). After adjustment for patient age, gender, body mass index, history of myocardial infarction, use of diuretics, angiotensin-converting enzyme inhibitors and β-blockers, estimated creatinine clearance rate, extent of coronary disease, left ventricular ejection fraction and left ventricular end-diastolic pressure, blood haemoglobin remained an independent predictor of plasma BNP (standardized β-coefficient=−0.253, P<0.0001). A similar relationship was observed between haematocrit and BNP (standardized β-coefficient −0.215, P<0.0001). We conclude that haemoglobin levels are independently predictive of plasma BNP levels in patients with suspected coronary heart disease without heart failure. Anaemia may contribute to elevated BNP levels in the absence of heart failure, and may represent an important confounder of the relationship between BNP, cardiac function and prognosis.