Avinash S, Singh V P, Agarwal A K, Chatterjee S, Araya V
J Assoc Physicians India. 2015 Nov;63(11):28-35.
Cystatin C is a low molecular weight protein produced by all nucleated human cells, with a stable production rate. Its levels are not influenced by inflammation, infections, hepatic or renal diseases, or by dietary or constitutional factors. We compared serum cystatin C and serum creatinine based predicting equations to estimate glomerular filteration rate (GFR) in type 2 diabetes mellitus, using the staging of chronic kidney disease (CKD) defined by the National Kidney Foundation. We also explored the relationship of urine albumin, GFR, serum creatinine and cystatin C concentrations.
: A cross-sectional study was performed at a tertiary care hospital in New Delhi. Consecutive patients with type 2 diabetes mellitus above the age of 35 years were enrolled. Fasting and 2-hour-postprandial blood glucose, fasting lipid profile, lipoprotein(a), haemoglobin, microalbuminuria, glycated haemoglobin (HbA1c), liver and renal function tests were assessed. Serum levels of Cystatin C were measured using immune-turbidometric method (Dade Behring analyzer BN2). Estimated GFR (eGFR) was calculated using Cockcroft-Gault formula, Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease-Epidemiology (CKD-EPI) Cys C formula. The three sets of eGFR were compared using repeated measure ANOVA. Linear regression analysis was performed to find the factor that affects the albumin excretion rate (AER) and e-GFR levels using all three equations.
We assessed 172 patients with type 2 diabetes mellitus. Mean age of the patients was 61.4 ± 9.6 years with mean duration of diabetes of 11.40 ± 7.5 years. Approximately 70% of patients had hypertension. A family history of diabetes was present in 53.4% of subjects and a history of CAD in first degree relatives in 20.9%. The prevalence of coronary artery disease was 17.4%. Albumin excretion correlated with e-GFR estimated using each of the three equations. The best correlation was seen with the CKD-EPI equation derived e-GFR. The CKD-EPI equation also identified the maximum number of patients in the normo-albuminuria group as having CKD. Albuminuria correlated with blood urea levels (p = 0.014) and serum cystatin C levels (p < 0.005).
The new cystatin C based Chronic Kidney Disease Epidemiology equation identifies more patients in early CKD and also patients with normo-albuminuric CKD compared to the creatinine based Cockcroft-Gault equation or the Modification of Diet in Renal Disease formulae.
胱抑素C是一种由所有有核人类细胞产生的低分子量蛋白质，其产生速率稳定。其水平不受炎症、感染、肝脏或肾脏疾病影响，也不受饮食或体质因素影响。我们使用美国国立肾脏基金会定义的慢性肾脏病（CKD）分期，比较了基于血清胱抑素C和血清肌酐的预测方程，以估计2型糖尿病患者的肾小球滤过率（GFR）。我们还探讨了尿白蛋白、GFR、血清肌酐和胱抑素C浓度之间的关系。
在新德里一家三级护理医院进行了一项横断面研究。纳入年龄在35岁以上的连续2型糖尿病患者。评估空腹及餐后2小时血糖、空腹血脂谱、脂蛋白（a）、血红蛋白、微量白蛋白尿、糖化血红蛋白（HbA1c）、肝功能和肾功能检查。使用免疫比浊法（达德拜耳分析仪BN2）测量血清胱抑素C水平。使用Cockcroft-Gault公式、肾脏病饮食改良（MDRD）公式和慢性肾脏病流行病学（CKD-EPI）胱抑素C公式计算估计的GFR（eGFR）。使用重复测量方差分析比较三组eGFR。进行线性回归分析，以使用所有三个公式找出影响白蛋白排泄率（AER）和e-GFR水平的因素。
我们评估了172例2型糖尿病患者。患者的平均年龄为61.4±9.6岁，糖尿病平均病程为11.40±7.5年。约70%的患者患有高血压。53.4%的受试者有糖尿病家族史，20.9%的受试者一级亲属有冠心病史。冠状动脉疾病的患病率为17.4%。白蛋白排泄与使用三个公式中的每一个估计的e-GFR相关。与CKD-EPI公式得出的e-GFR相关性最好。CKD-EPI公式还将正常白蛋白尿组中最多的患者识别为患有CKD。白蛋白尿与血尿素水平（p = 0.014）和血清胱抑素C水平（p < 0.005）相关。
与基于肌酐的Cockcroft-Gault公式或肾脏病饮食改良公式相比，基于胱抑素C的新慢性肾脏病流行病学公式能识别出更多早期CKD患者以及正常白蛋白尿性CKD患者。
