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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 T 31 pg/ml vs. 67 T 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 T 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 T 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.

Objectives: To examine N-terminal pro-brain natriuretic peptide (NT-proBNP) variability in plasma and urine samples of patients with stable heart failure (HF) during a 24-month follow-up. Design: Prospective study. Setting: Teaching hospital based study. Patients: 74 clinically and functionally stable patients (NYHA class 2¡0.5) out of 114 patients diagnosed with HF were followed up, and NT-proBNP plasma and urine levels were measured at baseline, 12 and 24 months. Results: Significant differences in mean urinary levels (p,0.01) were found during follow-up, but no changes were found in plasma. Bland-Altman plots showed few variations in plasma percentages in the three intervals (stage I-basal; stage II-stage I; stage II-basal) with a coefficient of reproducibility (CR) of 22%, 21% and 25%, respectively. Changes in NT-proBNP urinary levels had a CR of 7.1%, 6.8% and 9.4% at the three intervals, respectively. A good correlation was found between plasma and urinary levels of 0.001) and between the different NT-proBNP plasma (p,0.001) and urine measurements (p,0.001). Conclusions: NT-proBNP plasma and urine levels show good stability in a 24-month follow-up of patients with stable heart failure. Thus, assessment of urinary and plasma NT-proBNP concentrations may be a useful tool for monitoring patients with HF during follow-up. The results suggest that variations in peptide concentrations exceeding 22% in plasma and 7% in urine in a 12-month follow-up and 25% and 9% in a 24-month follow-up may indicate pathophysiological changes.

N-terminal pro-brain natriuretic peptide (NT-proBNP) may be useful in the diagnosis of heart failure and ventricular dysfunction. Obesity is an independent cardiovascular risk factor. The purpose of this study was to measure NT-proBNP plasma levels in obese and non-obese subjects with heart failure and to compare levels in subjects with ischaemic and dilated aetiology.In this study, obese subjects had 63% lower NT-proBNP plasma levels than non-obese subjects ( p < 0.01). In multivariate analysis, BMI was inversely associated with NT-proBNP plasma levels ( p < 0.05) and a 17% decrease in natriuretic peptide levels was attributed to obesity ( p < 0.036). When we analyzed data according to the aetiology of heart failure, we found that both groups (ischaemic and dilated) had a 65% decrease in NT-proBNP plasma levels in obese subjects compared to non-obese subjects.

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