Diagnostic and Prognostic Value of Urine NT-proBNP Levels in Heart Failure Patients

BACKGROUND: Plasma NT-proBNP levels are sensitive markers of ventricular dysfunction. However, studies of natriuretic peptides in urine are limited. AIMS: To compare urine and plasma NT-proBNP levels and to investigate the diagnostic and prognostic value of urine levels in heart failure (HF). METHODS: Urinary and plasma NT-proBNP levels were measured in 96 HF patients and 20 control subjects. The patients were functionally classified according to the NYHA criteria. RESULTS: Urine NT-proBNP was higher in HF patients than in control subjects (94+/-31 pg/ml vs. 67+/-6 pg/ml, p<0.0001), correlating with plasma NT-proBNP levels (r=0.78, p<0.0001). Urinary levels were elevated in the more severe functional classes and diminished in obese patients. Urine NT-proBNP was a good tool for diagnosis of HF, the area under the curve (AUC) being 0.96+/-0.02 (p<0.0001), and for predicting 12-month cardiac events (p=0.011). To determine the prognostic power of urinary NT-proBNP in detecting 12-month cardiac mortality, we obtained an AUC of 0.75+/-0.10 (p=0.015). CONCLUSION: Urinary NT-proBNP, a relatively simple non-invasive test, is a new candidate marker for the diagnosis and evaluation of prognosis in HF and for the characterization of functional status in these patients.