B-type natriuretic peptide versus amino terminal pro-B type natriuretic peptide: choosing the optimal heart failure marker in patients with impaired kidney function

Abstract

Introduction: B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) are novel HF markers but the effect of renal disease on these markers is not fully understood. Objective: To compare the levels of serum BNP and NT-proBNP in patients with compromised kidney function with and without HF. Study Design: Cross sectional. Place and Period: Consulting Clinics and Chemical Pathology Unit of Department of Pathology and Microbiology at Aga Khan University Hospital Karachi. From June 2009 to March 2010. Material and Method: Blood sample from adults with impaired kidney function for ≥3 months was obtained. Patients with documented HF with EF \u3c 40% were in the HF group. The demographic and clinical details of the patients were noted. Plasm was assayed for creatinine (Cr), BNP and NT-proBNP. Estimated glomerular filtration rate (eGFR) was calculated using the Cockcroft Gault formula. Results: The mean age of patients (n=190) was 58 years (±15 years), majority being males (67.4 %). BNP (r=-0.3) and NT-proBNP (r = - 0.5) rose with declining eGFR. Log mean BNP levels in the group with HF and impaired kidney function (n=95) was 2.4 ± 0.6 pg/ml as compared to those with impaired kidney function but no HF (n=95) 2.0 ±. 0.4 pg/ml (p\u3c0.01). Log mean NT-proBNP levels in the HF group was 3.9 ± 0.6 pg/ml as compared to those with no HF 2.9 ±. 0.6 pg/ml (p \u3c0.01). Conclusion: Plasma NT-proBNP was much higher as compared to BNP in the HF group and concentrations of BNP and NT-proBNP are not interchangeable. NT-proBNP appears to be affected more by declining eGFR, in keeping with the hypothesis that its clearance is predominantly renal. Keywords: heart failure, kidney, chronic, biomarke