肾功能与N末端B型钠尿肽原的关系及其在慢性心力衰竭诊断中的应用

目的通过观察人血清预测肾小球滤过率(eGFR)与N末端B型钠尿肽原(NT-proBNP)之间的关系,比较慢性心力衰竭(简称心衰)患者不同eGFR水平NT-proBNP的诊断界值(cut-off值),研究肾功能对NT-proBNP应用于心衰诊断的影响。方法选择我院2003年10月至2004年4月明确诊断为心衰的住院患者106例(心衰组)以及同期正常对照191名(对照组)。采用电化学发光法测定受试者血清NT-proBNP浓度,应用Levey改良的饮食校正公式计算eGFR。结果肾功能异常者[eGFR<60ml·(min·1·73m2)-1]的NT-proBNP中位数水平显著高于肾功能正常者[eGFR≥60ml·(min·1·73m2)-1],无论是在心衰组(829·1ng/Lvs·227·2ng/L,P<0·01)还是对照组(85·5ng/Lvs·50·4ng/L,P<0·01)。将NT-proBNP与eGFR进行对数转换后,二者呈负相关(心衰组r=-0·271,P<0·01;对照组r=-0·353,P<0·01)。NT-proBNP诊断肾功能正常心衰患者的cut-off值为162·3ng/L,敏感度为68·3%,特异度为98·1%,阳性预测值(PPV)为94·9%,阴性预测值为(NPV)85·3%,AUC为0·901;而诊断肾功能异常心衰患者的cut-off值明显升高,为238·8ng/L,敏感度为70·8%,特异度为100%,PPV为100%,NPV为84·1%,AUC为0·863。结论肾功能与NT-proBNP呈微弱相关,肾功能异常时NT-proBNP诊断心衰的cut-off值升高,可以作为合并肾功能不全心衰的诊断指标。

Influence of renal function on NT-proBNP in patients with chronic heart failure

Objective To investigate the influence of renal function on serum NT-proBNP in the diagnosis of chronic heart failure by observing the relationship between eGFR and NT-proBNP in serum and comparing cutoff values of NT-proBNP in different eGFR levels.Methods 297 elderly participants were enrolled in the study, including 106 inpatients with heart failure and 191 healthy controls in the corresponding period.The concentration of NT-proBNP was determined by an automated electrochemiluminescence immunoassay on Roche Elecsys 2010.Estimated glomerular filtration rate (eGFR) was calculated using the Levey-modified Modification of Diet in Renal Disease formula. The diagnosis of clinical physician was considered to be the golden standard for heart failure.Results Serum NT-proBNP levels were significantly higher in subjects with renal dysfunction compared with those with normal renal function for heart failure patients [829.1 (202.4 ~ 3725.5) ng/L vs. 227.2 (111.1 ~ 964.2) ng/L, P<0.01] as well as healthy controls [85.5 (59.3 ~ 146.2) ng/L vs. 50.42 (33.1 ~ 90.9) ng/L, P<0.01]. eGFR showed negative correlation with NT-proBNP in patients with heart failure (r=-0.271,P<0.01) and healthy controls (r=-0.353,P<0.01). ROC analysis revealed that the optimal cutoff value for heart failure patients with renal dysfunction (238.8 ng/L) was higher than those with normal renal function (162.3 ng/L). Sensitivity, specificity, positive prognostic value (PPV) and negative prognostic value (NPV) for renal dysfunction group were 68.3 %, 98.1 %, 94.9% and 85.3%, respectively and for normal renal function group were 70.8%,100%,100% and 84.1%,respectively. The area under the receiver operating characteristics curve (AUC) were 0.901 and 0.803, respectively.Conclusions Renal function correlates weakly with NT-proBNP and influences the optimal cutoff value for NT-proBNP in heart failure. Diagnosis of heart failure with NT-proBNP should take renal function into consideration. NT-proBNP could be used as a diagnostic marker for heart failure patients with renal dysfunction.