不同体质量老年脑梗患者血清胱抑素C与肾小球滤过率的相关性研究

Correlation between serum Cystatin C and glomerular filtration rate in elderly cerebral infarction patients with different body mass index

目的正确评定老年人的肾功能,对于指导临床用药及饮食很重要,探讨老年人体质量、血清肌酐、血胱抑素C与肾小球滤过率(GFR)的关系及临床意义。方法回顾性分析上海市宝山区中西医结合医院77例老年脑梗后住院康复治疗患者临床资料,按照体质量≤20 kg/m^2和体质量>20 kg/m^2分组,所有患者均于空腹测量体质量、留取血清,采用全自动生化仪检测血肌酐(Scr)、血胱抑素C,采用简化Modification of Diet in Renal Disease(MDRD)方程式、Cockcroft-Gault(C-G)方程式及基于胱抑素C公式估算GFR,并分析体质量、血肌酐、血胱抑素C与GFR的相关性。结果体质量≤20 kg/m^2组平均血肌酐(68.53±28.04)μmol/L较体质量>20 kg/m^2组平均血肌酐的(79.72±18.90)μmol/L明显降低,差异有统计学意义(P<0.05);平均胱抑素C(1.12±0.42)mg/L与体质量>20 kg/m^2组(1.05±0.31)mg/L比较,差异无统计学意义(P>0.05);用C-G公式估算GFR(45.69±23.10)ml/(min·1.73 m^2)较体质量>20 kg/m^2组的(63.46±24.23)ml/(min·1.73 m^2)明显降低,两组比较差异有统计学意义(P<0.05),用简化MDRD公式估算GFR(95.33±63.98)ml/(min·1.73 m^2)与体质量>20 kg/m^2组的(75.76±23.09)ml/(min·1.73 m^2)比较,差异有统计学意义(P<0.05);基于胱抑素C公式估算GFR(80.61±28.64)ml/(min·1.73 m^2)与体质量>20 kg/m^2组的(76.15±30.36)ml/(min·1.73 m^2)比较,差异无统计学意义(P>0.05)。两组之间经性别矫正后作线性回归分析提示:血清肌酐水平随体质量降低而降低,胱抑素C与体质量线性关系不显著,三种公式推导的GFR,C-G公式及MDRD公式均受年龄及体质量的影响,而胱抑素C公式则不受年龄、体重的影响,在两个组别里均比较稳定。结论胱抑素C是一个相对比较恒定的指标,能准确反映老年人的肾功能变化。

Objective Precisely evaluating the renal function helps to provide the guidance for clinical therapy and diet. This subject was objected to explore the relationship among body mass index(BMI), serum creatinine(Scr), serum Cystatin C and glomerular filtration rate(GFR) in elders.Methods A retrospective study was conducted in Baoshan Hospital of Integrated Traditional Chinese Medicine and Western Medicine in Shanghai. A total of 77 elderly individuals with cerebral infarction were enrolled and classified into two groups based on BMI(BMI≤20 kg/m^2 and BMI>20 kg/m^2).BMI was assessed at fasting states. Fasting Scr and fasting serum Cystatin C were measured using automatic biochemistry analyzers. The modification of diet in renal disease(MDRD) equation, CockcroftGault(C-G) equation and the equation based on cystatin C(Cys-EPI) were applied to evaluate GFR, the association between BMI, Scr, serum Cystatin C and GFR were assessed in the same time. Results The mean Scr values were significantly lower in BMI≤20 kg/m^2(68.53±28.04 μmol/L)than in BMI>20 kg/m^2[(79.72±18.90) μmol/L]. Moreover, no significant difference was identified in average serum Cystatin C levels between the two groups [BMI≤20 kg/m^2,(1.12±0.42) μmol/L and BMI>20 kg/m^2,(1.05 ± 0.31) μmol/L]. The estimated GFR evaluated based on C-G equation was(45.69±23.10) ml/(min · 1.73 m^2) in BMI≤20 kg/m^2, which was significantly lower than in BMI>20 kg/m^2[(63.46 ± 24.23) ml/(min · 1.73 m^2) ]. Similar results were obtained based on MDRD equation, and the estimated GFR was(95.33±63.98) ml/(min · 1.73 m^2) in BMI≤20 kg/m^2,(75.76±23.09)ml/(min · 1.73 m^2)in BMI>20 kg/m^2. However, the estimated GFR showed no significant difference between the two groups when using Cys-EPI equation, and the estimated GFR was(80.61±28.64) ml/(min · 1.73 m^2) in BMI≤20 kg/m^2,(76.15±30.36) ml/(min · 1.73 m^2) in BMI>20 kg/m^2.The Scr levels were negatively associated with BMI in linear regression analysis adjusting for gender.No significant association was identified on serum Cystatin C and BMI. In addition, the estimated GFR was significantly associated with age and BMI when C-G and MDRD equations were applied,and as to Cys-EPI equation, the estimated GFR remained consistent in the two groups. Conclusion Serum Cystatin C may serve as a stable biomarker that can precisely indicate the changes of renal functions in the elderly, especially in elders with low BMI.