半胱氨酸蛋白酶抑制剂C-一种新的儿童肾小球滤过率的内源性标志物

目的 :探讨半胱氨酸蛋白酶抑制剂C(cystatinCCys -C)作为一种新的儿童肾小球滤过率 (GFR)标志物的临床应用价值。方法 :检测了 5 0例健康儿童和 5 0例有各种肾脏疾病儿童的血清Cys -C、血清肌酐 (Scr)及 2 4小时尿肌酐 ,并计算出肌酐清除率 (Ccr)作为GFR的粗略标志物。结果 :对照组与患者组Cys -C的差别有显著性意义 (P <0 .0 5 )。 1/ys-C与GFR的相关性(r=0 .87)比 1/Scr与GFR的相关性 (r=0 .69)好。经logistic回归分析表明 ,血清Cys-C浓度仅与GFR有关 ,而与受试对象的年龄、身高和体重无关。根据ROC曲线下的面积可知Cys -C诊断GFR下降的准确性高于Scr和身高 /Scr。再由此得血清Cys -C的最佳截断点为 1.40mg/L ,据其诊断GFR下降的敏感性为 96% ,特异性为 91% ,准确性为 94%。结论 :血清Cys-C反映儿童肾脏功能不受年龄、身高、性别、体重等肾外因素的影响 ,其产生速率恒定只能通过肾小球滤过排泄 ,是一种理想的儿童GFR标志物。

Cystatin C:new endogenous marker of glomerular filtration rate in children

Objective To obtain a ideal marker of glomerular filtration rate(GFR),we evaluated the clinical usefulness of cystatin C (Cys-C) in terms of estimation for glomerular filtration rate in children.Methods We determined the cystatin C level in the serum and the creatinine level in the serum and urine of 50 healthy children aged 1 to 16 years as well as in the serum and urine of 50 patients with various renal diseases aged 1 to 15 years,24-hour creatinine clearance was used as an indicator of GFR.Results Reference intervals with 95% ranges of serum cystatin C are (1.03±0.47)mg/L from healthy children.The cystatin C level in the serum of the patients with various renal diseases were significantly higher than that in control group (P<0.05).The reciprocal of cystatin C correlated better with GFR (r=0.87) than the reciprocal of creatinine (r=0.69).Logistic regression analysis identified that the cystatin C level in the serumonly correlated with GFR ,by contrast,the creatinine level in the serum correlated with age,heigh and weight besides GFR.Diagnostic accuracy in the identification of GFR reduction was measured by area under the receiver-operating characteristic plot that serum cystatin C was more accurate than creatinine and height/creatinine.A cutpoint cystatin C concentration of 1.40mg/L had 96% sensitivity,91% speciality and 94% accuracy for detecting GFR reduction.Conclusion Unlikecreatinine,serum cystain C reflects renal function in children independent of many extrinsic factors such as age,height,sex and weight.The constant production rate of cystatin C in all the tissues and its elimination only via the glomerular filter,cystatin C is an ideal marker of glomerular filtration rate in children.