Effect of Renal Dysfunction on N-Terminal Pro-B-Type Natriuretic Peptide; A Canine Biomarker for Heart Disease
N-terminal B-type natriuretic peptide (NT-proBNP) is secreted from the cardiac ventricles in response to volume expansion or pressure overload. This peptide has previously been shown to distinguish cardiac and noncardiac causes of dyspnea in humans and dogs. In humans with kidney disease, BNP concentration can be elevated due to decreased renal clearance, and clinical interpretation of these markers must take renal function into account. The aim of this study is to determine the effects of kidney dysfunction on serum NT-proBNP concentrations in dogs. In total, 28 dogs were examined by physical examination, echocardiography, renal panel, non-invasive blood pressure measurement, urinalysis, and serum NT-proBNP assay (Canine CardioCare, Veterinary Diagnostics Institute, Irvine CA). Twenty-two healthy control dogs and 6 dogs with renal disease but without a heart murmur, valvular, or primary myocardial disease were recruited. Mean NT-proBNP in control dogs was 282 pmol/L, range of 179-578 pmol/L. Compared with controls, NT-proBNP was significantly increased in dogs with kidney dysfunction (mean=1069 pmol/L; range 179-2071 pmol/L;P=0.0004). These results suggest that renal insufficiency may falsely increase serum NT-proBNP; however a high degree of variability was present within the kidney dysfunction group. Optimal NT-proBNP cut-off values for the diagnosis of heart disease or heart failure in dogs with concurrent renal dysfunction should be investigated.