Anemia is independently associated with NT-proBNP levels in asymptomatic predialysis patients with chronic kidney disease

Background: Although anemia and renal dysfunction are related to increased natriuretic peptides levels in heart failure patients, less is known about this relationship in asymptomatic predialysis patients with chronic kidney disease (CKD). The aim of this study was to investigate relationship between hemoglobin (Hb) concentration, N-terminal proBNP (NT-proBNP) levels and echocardiographic findings in these patients. Methods: The study included 61 patients with CKD stage IV-V (34 male, mean age 62.6 +/- 13.6 years) and 22 age-and sex -matched healthy persons as control group. All participants underwent clinical, laboratory and echocardiographic examination, including Tissue Doppler Imaging and colour M-mode Doppler. Results: Patients with CKD had lower Hb levels (p<0.001), and higher levels of NT-proBNP (p<0.001) than healthy controls. Patients were divided into two groups according to their mean Hb levels: group A, Hb<10.3 g/dL and group B, Hb >= 10.3 g/dL. Patients from group A was significantly older (p<0.001), left ventricular mass index was significantly higher (LVMI, p<0.001), LV diastolic function was worse (septal and lateral E'/A' ratio: p<0.05 and p<0.01, respectively), and the level NT-proBNP was higher (p<0.001) compared to patients from group B. The natural logarithm of NT-proBNP (lnNT-proBNP) showed highly significant correlation with Hb (p<0.001) and significant correlation with estimated glomerular filtration rate (p=0.035) in CKD patients. Multiple regression analysis revealed Hb levels (p<0.01), cholesterol (p<0.001), LV ejection fraction (p<0.001) and septal E/E' ratio (p<0.01) as the independent variables predicting as much as 54% variability of lnNTpro-BNP. Conclusions: The increased NT-proBNP levels in asymptomatic patients with advanced CKD were independently associated with echocardiographic parameters of LV function, but anemia may represent one of the important confounder of the relationship between NT-proBNP and cardiovascular abnormalities.