Diagnostic Values of Plasma, Fresh and Frozen Urine NT-proBNP in Heart Failure Patients

Introduction: The plasma N-terminal probrain natriuretic peptide (NT-proBNP) level is animportant diagnostic and prognostic marker of heart failure. Recent studies have suggestedurinary NT-proBNP as a new and simple test for diagnosis of heart failure. We aim to comparediagnostic value of plasma, fresh and frozen urine levels of N-terminal probrain natriureticpeptide (NT-proBNP) for detecting heart failure.Methods: Between January 2010 and January 2012, we measured urine and plasma levels of NTproBNPin 98 patients with chronic heart failure (CHF) and 29 age- and sex-matched healthycontrol subjects.Results: There were significant correlations between plasma NT-proBNP and fresh (r=0.45,p 0.001) and frozen (r=0.42, p 0.001) urine NT-proBNP concentrations in CHF patients. Due toreceiver operating curve analysis, fresh and frozen urine NT-proBNP could diagnose HF with areaunder curve (AUC) of 0.73±0.04 (p 0.001) and 0.65±0.05 (p=0.01) with sensitivity and specificityof 73.97%, 58.62%, and 65.31%, 62.07%, for a cut-off of 94.2 and 96 pg/mL, respectively. PlasmaNT-proBNP had greater AUC (0.94±0.02, p 0.001) and better sensitivity and specificity (94.9%,89.66% for cut-off of 414.5 pg/mL). There was no significant correlation between LVEF andplasma, fresh and frozen urine NT-proBNP levels in CHF patients.Conclusion: Plasma NT-proBNP is still the best diagnostic marker with high sensitivity andspecificity; however, urinary especially fresh urine NT-proBNP may be a surrogate to plasma NTproBNPfor diagnosing HF with acceptable accuracy.