The clinical significance of urinary B-type natriuretic peptide assay for the diagnosis of chronic heart failure

Objective To investigate the value of urinary BNP for diagnosis of chronic heart failure (CHF). Methods The levels of Urinary BNP and plasma BNP were measured by microparticle enzyme immunoassay (MEIA) in 83 patients with CHF and 30 control subjects. The heart function was classified according to the NYHA criteria. Left ventricular ejection fractions (LVEF) were measured by echocardiology. Results The level of urinary BNP in patients with CHF was[90. 0(38. 3 -209. 5 )]ng/L and the level of plasma BNP was[680. 0 ( 289. 7 - 1543.5)]ng/L, both of them were much higher than those in healthy subjects,[17. 0 ( 13.0 - 33. 0)]ng/L and[84. 5 ( 56. 0 - 158.0 )]ng/L, respectively (P＜0. 01 ). The concentrations of urinary BNP increased gradually with more severe symptoms ( NYHA cl ass Ⅰ -ⅣV ). The level of urinary BNP was positively correlated with NYHA class ( r = 0. 742, P ＜ 0. 01 )and the level of plasma BNP (r =0. 842,P ＜0. 01 ) while negatively related with LVEF (r = -0. 801 ,P ＜0. 01 ). The level of urinary BNP in patients with LVEF ＜ 40％ was[143.0 ( 85. 0 - 258.0)]ng/L , which was much higher than that in patients with LVEF≥40％ ,[31.5( 17.3 -38. 8)]ng/L, (P ＜0. 01 ). At a decision threshold of 36. 5 ng/L, the urine BNP assay demonstrated a clinical sensitivity and specificity of 84％ and 80％ ,respectively. In this study,the area under the curve(AUC) was 0. 905. Conclusion Urinary BNP is a new candidate marker for the diagnosis of CHF,it provides a similar accuracy with plasma BNP. Key words: Heart failure;  Natriuretic peptide, brain;  Urinalysis