血清胱抑素C：一种简便测定肾小球滤过率的标志物

目的 :评价测定肾小球滤过率 (GFR)的一种简便方法—血清胱抑素C检测的临床意义。方法 :对 5 0例不同肾病患者及70名正常人同时测定血清胱抑素C及内生肌酐清除率、血肌酐值 ,并对两组结果进行相关分析。结果 :血清胱抑素C与内生肌酐清除率及血肌酐值有高度相关性 (r值分别为r =- 0 .83 4 ,p <0 .0 0 1和r =0 .867,p <0 .0 0 1)。结论 :血清胱抑素C检测是一种简便、可靠测定GFR的标志物     

胱氨酸蛋白酶抑制剂C的临床应用

目的　进一步证实血清胱氨酸蛋白酶抑制剂C在评价肾小球滤过功能方面的价值。方法　用颗粒增强散射免疫比浊法检测 1 6 4例肾脏损害患者血清胱氨酸蛋白酶抑制剂C的浓度 ,并与其血清尿素、肌酐、内生肌酐清除率相比较。结果　胱氨酸蛋白酶抑制剂C与内生肌酐清除率之间高度相关 (P <0 .0 1 )。结论　胱氨酸蛋白酶抑制剂C是一种理想的反映肾小球滤过率 (GFR)的标志物 ,能替代操作繁琐的内生肌酐清除率来判断肾小球滤过功能     

应用血清西司他汀浓度测定评价早期糖尿病肾病肾小球功能

目的　测定 2型糖尿病早期肾病患者血清西司他汀浓度 (CystatinC ,CysC) ,观察其变化情况 ,以评价糖尿病早期肾病肾小球功能。方法　住院的 14 1例 2型糖尿病患者 ,根据 2 4小时尿微量白蛋白排泄率 (Urinealbuminexcretionrate ,UAER)分为三组 :A组 ,UAER <30mg 2 4h ;B组 ,UAER 30～ 30 0mg 2 4h ;C组 ,UAER≥ 30 0mg 2 4h。采用散率散射比浊法对所有患者测定CysC ,并与内生肌酐清除率 (creatinineclearancerate ,Ccr)比较。结果　与正常对照组比较 ,B、C两组UAER、CysC均高于正常对照组 ,Ccr低于正常对照组 (P <0 . 0 1) ,A组与正常对照相似 (P >0 . 0 5 ) ;3组之间比较 ,CysC、UAER值C组明显高于B、A组 ,B组高于A组 ;Ccr值C组低于B、A组 ,B组低于A组 (P <0 . 0 1)。相关分析显示 ,CysC与UAER呈显著正相关 ,与Ccr呈显著负相关 (P <0 . 0 1)。结论　CysC能较准确反映肾小球滤过功能 ,而且测定只需一份血标本 ,不需收集尿标本 ,方法简便、快捷。     

胱抑素C检测在肾功能损害诊断中的应用研究

目的研究和探讨血清胱抑素C（CysC）的检测在对肾病患者肾功能损害诊断和评估中的临床应用价值。方法采用胶乳增强免疫比浊法、脲酶比色法、苦味酸速率法分别对健康对照组、高危肾病组、各类肾病患者组共598例研究对象进行CysC、尿素Urea）、肌酐（Scr）检测,对肾病组患者按内生肌酐清除率（Ccr）将肾损害不同期进行分组,再将各研究组检测的各项结果进行统计比较及分析。结果高危肾病组及肾病组中Ccr正常期的患者组（A组）和肾功能储备下降期组fB组）患者的Urea、Scr检测结果与健康对照组的结果差异无统计学意义（P〉0．05）,而CysC检测结果显示高危肾病组差异有统计学意义（P〈0．05）,肾病各期组则均差异有统计学意义（P〈0．01）,肾病各期组的CysC结果与Ureat和Scr呈显著正相关性（r=0．858,r=O．873）,而与Ccr呈显著负相关（r=-0．758）;高危肾病组及肾病组各期患者CysC阳性检出率也明显优以各自的Urea、Scr阳性检出率。结论血清CysC指标是一个比Urea、Scr及Ccr更为敏感、准确反映肾小球滤过率（GFR）功能的理想指标．对肾病患者早期肾功能损害诊断和评估中具有更重要的临床应用价值。     

血清胱抑素C水平与IgA肾病临床及病理特征的相关性

目的探讨血清胱抑素C(CysC)与IgA肾病临床及病理特征的相关性。方法收集2010年1月至2021年1月在上海中医药大学附属龙华医院经肾活检确诊的原发性IgA肾病421例进行回顾性分析。根据肾活检时血清CysC水平分为血清CysC高水平组(≥1.03 mg/L)及CysC正常组, 对患者的临床资料及病理指标进行比较, 采用Spearman法分析估算的肾小球滤过率(eGFR)与血清CysC的相关性, 多元线性回归分析与血清CysC水平相关的临床病理因素, 并用受试者工作特征(ROC)曲线下面积(AUC)评估联合血清CysC预测相关病理损伤的能力。结果 CysC高水平组患者的年龄、合并高血压、血肌酐、尿素及血尿酸水平均明显高于血清CysC正常组, 而eGFR水平明显低于血清CysC正常组(P均<0.05)。Spearman相关性分析显示, 血清CysC与eGFR呈负相关(r=-0.744, P<0.001)。在病理损伤方面, CysC高水平组在肾小管萎缩与肾间质纤维化及肾小动脉管壁增厚等程度高于CysC正常组(P均<0.05)。多元线性回归分析提示, 高血压、血肌酐、尿...     

胱抑素C在糖尿病性肾病中评估肾小球滤过率的价值研究

目的比较不同阶段2型糖尿病肾病患者血清胱抑素C(CysC)水平,探讨相关性。方法将柳州医学高等专科学校第一附院收治的2型糖尿病患者148例,按内生肌酐清除率Ccr值分为三组,测定各组CysC水平、血肌酐(Scr),计算内生肌酐清除率(Ccr)、C-G公式计算的肾小球率过滤(CG-GFR)。结果研究组各组间血清胱抑素C有显著差异。以Ccr 90ml/(min.1.73m2)或60ml/(min.1.73m2)为切点作ROC曲线,三者之中,CysC对Ccr的诊断效能最强,CG-GFR次之,血肌酐最弱。结论血清CysC水平的升高与糖尿病肾病密切相关,CysC比血肌酐、CG-GFR可更敏感地评估早中期肾功能损害的改变。     

胱抑素C在肾脏疾病中的临床应用评价

目的:探讨血清胱抑素C(SCysC)作为肾小球滤过率指标在肾脏疾病中的临床应用价值。方法:采用乳胶颗粒增强免疫比浊法(PETIA)测定40例健康体检者和85例肾病患者血清中CysC的浓度,并与血尿素(Urea),血肌酐(SCr),内生肌酐清除率(Ccr),血β2-微球蛋白(β2-MG)进行比较。结果:肾病患者SCysC浓度随内生肌酐清除率的下降而逐渐升高,当Ccr≥80mL/min/1.73m2时,SCysC、β2-MG与健康对照组比较有统计学差异(P&lt;0.05,P&lt;0.01),Urea、SCr与对照组无差异。且SCsyC和β2-MG的阳性检出率明显高于Urea、SCr。结论:血清胱抑素C在应用于临床评价肾小球滤过功能时是一种更为准确、可靠、灵敏的指标。     

简易内生肌酐清除率测定

目的　验证简易内生肌酐清除率判断肾小球滤率的可行性。方法　用简易内生肌酐清除率测定法测定 1 7例患者的内生肌酐清除率 ,同时测定传统的 2 4小时内生肌酐清除率 ,并以菊粉清除率为标准方法 ,对三组测定结果进行配对t检验及相关性比较。结果　简易内生肌酐清除率与菊粉清除率高度相关 (r=0 .991 ) ,配对t检验无显著性差异 (P >0 .0 5) ;2 4小时内生肌酐清除率与菊粉清除率配对t检验有显著性差异 (P <0 .0 1 ) ,呈假性增高。结论　简易内生肌酐清除率测定是一种安全、可靠、便利测定GFR的方法 ,测定结果与菊粉清除率一致 ,可替代传统的 2 4小时内生肌酐清除率测定。     

糖尿病肾病血清胱抑素C的变化及与肾小球滤过率的相关性研究

目的通过检测胱抑素C(CysC)及尿微量白蛋白清除率(UAER)在糖尿病肾病进程中的变化以及与肾小球滤过率(GFR)的相关性,探讨其在糖尿病肾病诊断中的价值。方法共47例患者,采用示踪剂99mTc-二乙胺五乙酸(99mTc-DTPA)检测GFR,将其分为早期糖尿病肾病组及晚期糖尿病肾病组,比较两组间CysC、UAER的变化及评判基于血清CysC计算的GFR(CGFR)与传统肾脏病膳食改良试验(MDRD)方程计算的GFR估计值(eGFR)的优劣。结果晚期糖尿病肾病组CysC、UAER均高于早期糖尿病肾病组(P<0.01),99mTc-DTPAGFR与CGFR无统计学差异(P>0.05),eG-FR显著高于99mTc-DTPAGFR与CGFR(P=0.006;P=0.033)。相关分析显示GFR与CysC、UAER负相关(r=-0.584,P=0.000;r=-0.507,P=0.000)。结论糖尿病患者中,伴随慢性肾脏病(CKD)进程,CysC、UAER逐渐升高,与eGFR相比,CGFR与GFR有更好的对应性,能更好地反映糖尿病肾病患者肾小球滤过功能异常。     

胱抑素C及同型半胱氨酸的血清含量与糖尿病肾病患者肾小球滤过率的相关性研究

目的:通过检测血胱抑素C(CystatinC,CysC)、同型半胱氨酸(Homocysteine,Hcy)浓度及尿白蛋白清除率(urinealbumin excretionrate,UAER)在糖尿病肾病(diabetic nephropathy,DN)进程中的变化以及与肾小球滤过率(glomerular filtration rate,GFR)的相关性,探讨其在DN诊断中的价值。方法:共47例患者,根据肾小球滤过率将其分为早期糖尿病肾病组(early-DN组,GFR≥60mL/min)及晚期糖尿病肾病组(end-DN组,GFR<60mL/min),比较两组间CysC、Hcy的变化以及与肾小球滤过率的相关性。结果:end-DN组CysC、UAER均高于early-DN组(P<0.01)。相关分析显示肾小球滤过率与CysC、Hcy、UAER负相关(r=-0.584,P=0.000;r=-0.547,P=0.000;r=-0.507,P=0.000),在慢性肾脏病(chronic kidney disease,CKD)Ⅱ、Ⅲ期,肾小球滤过率与CysC、Hcy负相关(r=-0.617,P=0.000;r=-0.431,P=0.018)。结论:糖尿病患者中,伴随慢性肾脏病进程,CysC、Hcy、UAER逐渐升高,尤其在CKDⅡ、Ⅲ期,CysC、Hcy联合检测与UAER比较,能更好的反应糖尿病肾病肾小球滤过功能异常。     

Analysis of glomerular filtration rate, serum cystatin C levels, and renal resistive index values in cirrhosis patients.

BACKGROUND: The aim of this study was to evaluate the relation of glomerular filtration rate (GFR) to serum cystatin C levels, renal resistive index (RRI), serum creatinine and creatinine clearance in patients with different stages of cirrhosis. METHODS: The study sample was 25 cirrhotic patients (10 females and 15 males; mean age 57.3+/-2.04 years), 10 in the compensated stage without ascites and 15 in the decompensated stage with new-onset ascites. None had azotemia nor were on diuretic treatment. The control group comprised 25 healthy adults (11 female and 14 men; mean age 56.56+/-1.91 years). Serum cystatin C, RRI, serum creatinine and creatinine clearance were measured. GFR was determined by technetium(99m)-diethylene triamine pentaacetic acid renal scintigraphy. RESULTS: Cirrhosis cases had lower mean scintigraphic GFR than controls (64.5+/-4.03 vs. 87.96+/-4.16 mL/min, p<0.05). Serum cystatin C and RRI were significantly higher in the cirrhotic group compared to controls (1.16+/-0.09 mg/L and 0.68+/-0.01 vs. 0.86+/-0.03 mg/L and 0.64+/-0.01, respectively; p<0.05). Subgroup comparative analysis showed that only two parameters, scintigraphic GFR and serum cystatin C, were significantly different between compensated and decompensated cirrhotics (75.62+/-4.9 mL/min and 0.89+/-0.07 mg/L vs. 57.23+/-5.14 mL/min and 1.34+/-0.13 mg/L, respectively; p<0.05). Scintigraphic GFR showed significant correlation with cystatin C, but not with serum creatinine or creatinine clearance (r=-0.877, p<0.05) in decompensated patients. No correlation was observed between scintigraphic GFR and RRI or between serum cystatin C and RRI in all subjects. A receiver operator characteristics curve showed that cystatin C at a cutoff value of 1.01 mg/L can significantly differentiate patients with GFR <70 mL/min with 80% sensitivity and 80% specificity. CONCLUSIONS: Serum cystatin C, but not serum creatinine or RRI measurement, correlates with GFR in each stage of liver failure and has a significant diagnostic advantage in detecting lower GFR in such cases.     

Serum cystatin C assay for the detection of early renal impairment in diabetic patients

The ability to assess renal function in diabetes patients rapidly and early is of major importance. This study was designed to determine whether cystatin C can replace serum creatinine as the screening marker for reduced glomerular filtration rate (GFR) in type 2 diabetes patients. The study was performed on 51 type 2 diabetic patients. GFR was estimated by the plasma clearance of (99m)Tc-DTPA. The correlation between (99m)Tc-DTPA clearance and levels of serum cystatin C, serum creatinine, and creatinine clearance was determined. Sensitivity and specificity for the diagnosis of renal impairment (defined as GFR<68 ml/min) were calculated by a receiver operating characteristic (ROC) curve for serum cystatin C, serum creatinine, and creatinine clearance. The correlation coefficients with (99m)Tc-DTPA clearance were -0.744 for serum cystatin C, -0.658 for serum creatinine, and +0.625 for creatinine clearance (P<0.001). With a cutoff value of 68 mL/min, the area under the ROC curve (AUC) was 0.891 for cystatin C, 0.77 for creatinine, and 0.753 for creatinine clearance. The AUC was statistically different between serum cystatin C and creatinine clearance (P<0.05). The ROC plot indicates that cystatin C is superior to serum creatinine and creatinine clearance for detecting impaired GFR. Serum cystatin C appropriately reflects GFR in diabetes, and is more efficacious than serum creatinine and creatinine clearance in detecting reduced GFR in type 2 diabetes patients.     

Clinical value of serum cystatin C by ELISA for estimation of glomerular filtration rate

The search for whether endogenous markers of changes in glomerular filtration rate (GFR) by serum cystatin C assay and serum cystatin C compare with creatinine clearance by the Cockeroft-Gault formula and the evaluation of its clinical significance as a marker of GFR is important in clinical practice at present. Serum cystatin C was determined by sandwich enzyme immunoassay using a kit. Control blood samples were collected from 70 healthy subjects and 168 patients with various kidney diseases. Creatinine clearance (Cockeroft-Gault formula) as a measure of GFR, in 168 patients with various kidney diseases, depends on the creatinine clearance; GFR parameters were used to divide patients into two groups. The GFR was >80 mL/min in 38 patients (group A) and <80 mL/min in 130 patients (group B). The two groups were analyzed by correlation coefficient and diagnostic sensitivity and specificity were assessed by the receiver-operating characteristic (ROC) plots (area under the curve). Of the 70 healthy control individuals, the serum level of cystatin C was measured as normal value range and a reference interval of 1.05+/-0.18 micro g/mL (mean+/-1.96 SD, 95% confidence limits for the upper references limit is 1.4 microg/mL). In group A, serum cystatin C had no correlation to the creatinine clearance (r=0.171, P>0.05) and in group B, serum cystatin C was closely correlated to the creatinine clearance (r=-0.771, P<0.001). Diagnostic sensitivity and specificity were assessed by the ROC plots for serum cystatin C (area under the curve=0.8461, SE=0.057) and creatinine clearance (area under the curve=0.7642, SE=0.068). These data suggest that combined measurement of serum cystatin C is useful to estimate GFR, especially to detect the reduction of GFR. Further studies are required to evaluate the whether serum cystatin C as a more sensitive marker of early renal injury might be extremely useful, particularly in nonproteinuric or unapparent renal disease.     

Improved prediction of decreased creatinine clearance by serum cystatin C: use in cancer patients before and during chemotherapy

BACKGROUND: Serum cystatin C, a cysteine protease inhibitor, has been suggested as a new marker of glomerular filtration rate (GFR). This study explored the possibility of replacing the creatinine clearance (CrCl) estimation of GFR with cystatin C in early detection of renal impairment in cancer patients on chemotherapy. METHODS: Serum creatinine and cystatin C concentrations as well as 24-h CrCl were determined simultaneously in 72 cancer patients. Among them, 60 were treated with combined chemotherapy with cisplatin (CDDP). Creatinine was determined enzymatically with a spectrophotometric method. Serum cystatin C was determined by a particle-enhanced turbidimetric immunoassay. RESULTS: Cystatin C and creatinine correlated significantly (P = 0.001) with CrCl. The correlation was significantly better for cystatin C than creatinine (r = 0.84 vs 0.74; P = 0.01). Stepwise regression analysis identified no differences for the correlations between cystatin C and CrCl in patients with or without metastases (r = 0.82 and 0.84, respectively) as well as before treatment and before the fourth cycle of chemotherapy (r = 0.70 and 0.75, respectively). A cystatin C cutoff concentration of 1.33 mg/L had 87% sensitivity and 100% specificity for detecting CrCl <78 mL/min. ROC analysis indicated that cystatin C was superior to serum creatinine for predicting CrCl <78 mL/min (P <0.04). CONCLUSIONS: Serum cystatin C is superior to serum creatinine for detection of decreased CrCl and potentially for the estimation of GFR in cancer patients independent of the presence of metastases or chemotherapy.     

Diagnostic value of serum cystatin C for evaluation of hepatorenal syndrome

BACKGROUND: The evaluation of renal function in patients with decompensated cirrhosis is important for prognosis, dosage assessment of potentially nephrotoxic drugs and recognition of changes in glomerular filtration rate (GFR) to decide paracentesis and diuretic therapy. Patients with many different disorders of hepatic function can present with various abnormalities of renal function in the absence of other known causes of renal failure which has been called hepatorenal syndrome (HRS). Some reports have pointed out that serum creatinine levels frequently failed to rise above normal levels even when glomerular filtration rate (GFR) is very low in cirrhotic patients with hepatorenal syndrome. The aim of this study was to determine if estimation of serum cystatin C could replace creatinine clearance in routine GFR determinations for patients with cirrhosis. METHODS: Serum cystatin C, creatinine clearance (Clcr), and 99mTc-DTPA clearance were determined in 26 patients with cirrhosis. According to Child-Pugh's classification, 21 patients were in group C and 5 were in Group B. RESULTS: Pearson correlation analyses showed that correlation between serum cystatin C and 99mTc-DTPA clearance was r=-0.522, p=0.006, between serum creatinine and 99mTc-DTPA was r=-0.373, p=0.06. The results of our study demonstrated that neither serum creatinine nor creatinine clearance (Clcr) were good indicators of hepatorenal syndrome because the mean value for Clcr was found to be higher than Tc-DTPA clearance, and there was no correlation between these two parameters (r=0.059). Additionally, the mean value of serum creatinine was found to be within the normal range, whereas the mean DTPA clearance level was lower than normal range. CONCLUSIONS: This finding could be explained by the fact that cirrhotic patients with poor nutrition may have decreased protein intake, low muscle mass and lack of converting capacity of creatine to creatinine. Thus, we suggest that serum cystatin C assay, which has good analytical performance, could replace or at least be added to creatinine measurement for GFR assessment in patients with cirrhosis.     

慢性肾脏病患者不同肾损害时期血清胱抑素C的水平探讨

目的检测慢性肾脏病（CKD）患者血清中半胱氨酸蛋白酶抑制剂胱抑素C（Cystatin C）水平,探讨CKD不同肾损害期血清Cystatin C水平的变化情况。方法根据临床分期将研究对象分为CKDⅠ、Ⅱ、Ⅲ、Ⅳ、Ⅴ期组,采用胶乳增强免疫透射比浊法检测各组患者血清Cystatin C水平,同时测定血清肌酐（SCr）及内生肌酐清除率（Ccr）,并与健康对照组比较。结果CKD患者其他各期血清Cystatin C及Ccr与Ⅰ期组比较差异有统计学意义（P〈0.01）;各组患者血清Cystatin C水平与健康对照组比较差异有统计学意义（P〈0.01）;相关分析显示,血清Cystatin C与SCr之间呈高度正相关（r=0.781,P〈0.01）,与Ccr之间呈高度负相关（r=-0.815,P〈0.01）。在肾功能损害早期血清CystatinC改变较SCr更敏感（P〈0.01）。结论CystatinC是一种比SCr更好的反映肾小球滤过功能的指标,能反映CKD不同阶段中肾脏滤过功能的损害程度。     

Kidney function estimating equations in patients with chronic kidney disease

Background: The current guidelines emphasise the need to assess kidney function using predictive equations rather than just serum creatinine. The present study compares serum cystatin C‐based equations and serum creatinine‐based equations in patients with chronic kidney disease (CKD). Methods: Seven hundred and sixty‐four adult patients with CKD were enrolled. In each patient serum creatinine and serum cystatin C were determined. Their glomerular filtration rate (GFR) was estimated using three serum creatinine‐based equations [Cockcroft–Gault (C&G), modification of diet in renal disease (MDRD) and the Chronic Kidney Disease Epidemiology Collaboration equation (CKD‐EPI)] and two serum cystatin C‐based equations [our own cystatin C formula (GFR = 90.63 × cystatin C^?1.192) and simple cystatin C formula (GFR = 100/cystatin C)]. The GFR was measured using ⁵¹CrEDTA clearance. Results: Statistically significant correlation between ⁵¹CrEDTA clearance with serum creatinine, serum cystatin C and all observed formulas was found. The receiver operating characteristic curve analysis (cut‐off for GFR 60 ml/min/1.73 m²) showed that serum cystatin C and both cystatin C formulas had a higher diagnostic accuracy than C&G formula. Bland and Altman analysis for the same cut‐off value showed that all formulas except simple cystatin C formula underestimated measured GFR. The accuracy within 30% of estimated ⁵¹CrEDTA clearance values differs according to stages of CKD. Analysis of ability to correctly predict patient’s GFR below or above 60 ml/min/1.73 m² showed statistically significant higher ability for both cystatin C formulas compared to MDRD formula. Conclusion: Our results indicate that serum cystatin C‐based equations are reliable markers of GFR comparable with creatinine‐based formulas.     

半胱氨酸蛋白酶抑制剂C与肾移植后尿路梗阻患者的肾功能

背景：半胱氨酸蛋白酶抑制剂C不被肾小管分泌和重吸收,近年来被认为是一种非常理想的评价肾小球滤过率的指标。目的：探讨肾移植后输尿管狭窄患者血清半胱氨酸蛋白酶抑制剂C水平变化及其在肾功能损伤诊断中的价值。方法：选取2007年4月至2011年4月于深圳市第二人民医院泌尿外科及广州华侨医院泌尿外科行肾移植并于移植后发生输尿管狭窄伴肾功能不全的患者18例作为病例组,同时纳入同期年龄性别与病例组相匹配的健康体检者63名作为对照组。分别于输尿管狭窄治疗前及治疗后1个月测定患者血清半胱氨酸蛋白酶抑制剂C、肌酐、尿素氮水平并分析其相关性。结果与结论：与对照组比较,病例组输尿管狭窄治疗前半胱氨酸蛋白酶抑制剂C、血肌酐和尿素氮水平均显著增高（P〈0．01）;治疗后1个月,病例组半胱氨酸蛋白酶抑制剂C、血肌酐和尿素氮水平较治疗前显著降低（P〈0．01）。相关分析结果显示,肾移植后输尿管狭窄患者血清半胱氨酸蛋白酶抑制剂C水平与血肌酐和尿素氮水平呈正相关。提示血清半胱氨酸蛋白酶抑制剂C可作为肾移植后。肾功能恢复情况的监测指标。     

Cystatin C can be affected by nonrenal factors: a preliminary study on leukemia

OBJECTIVE: The aim of this study was to evaluate the influence of malignancy and the impact of nephrotoxic drugs used in bone marrow transplantation (BMT) on the circulating levels of cystatin C in leukemia. METHODS: We studied nineteen patients (eleven men and eight women; mean age 30.1 +/- 11.2, 27.9 +/- 7.1 years) with acute lymphoblastic leukemia, acute myeloid leukemia and chronic myeloid leukemia. Cystatin C, urea, creatinine and creatinine clearance (CrCl) were measured 24 h before BMT, 1 week after BMT, 2 weeks after BMT and 3 weeks after BMT. The control group consisted of twenty healthy adults, and the mean age was 29.1 +/- 8.9. RESULTS: At the pretransplantation period, values of cystatin C were significantly higher than in the control group (P < 0.05). Urea, creatinine and CrCl values were not statistically different from the controls. One week after BMT, the level of cystatin C was significantly low as compared to the levels measured 24 h before BMT, but was still significantly higher than the controls (P < 0.05), whereas the levels of urea, creatinine and CrCl were in accordance with the levels of the controls. Two and three weeks after BMT, cystatin C values maintained the significant increase (P < 0.05), whereas the values of urea, creatinine and CrCl still corresponded with those of the controls in both group. CONCLUSIONS: Our preliminary data expose that cystatin C is not a reliable GFR marker in patients during leukemia or for monitoring nephrotoxic drugs used in BMT, but we can not reach definitive conclusion due to no gold standard for comparing the diagnostic accuracy of cystatin C. Further study is needed to elucidate the precise mechanism underlying this observation.     

Variation of serum creatinine, cystatin C, and creatinine clearance tests in persons with normal renal function

BACKGROUND: To determine the potential sensitivity of several renal function tests for detecting early changes in renal function, we compared the within-individual (W-I) variation over 5 months of serum creatinine, serum cystatin C, and creatinine clearance. METHODS: On 31 healthy subjects, blood and timed urine specimens were collected once each month to get 6 collections. Creatinine (enzymatic) in serum and urine and cystatin C (immunonephelometric) in serum were measured and glomerular filtration rate (GFR) by creatinine clearance and the Modification of Diet in Renal Disease (MDRD) equation were calculated. To compare W-I variations between different creatinine methods, we also measured creatinine by both enzymatic and kinetic alkaline picrate methods on 15 sets of frozen samples. RESULTS: For the 31 volunteers, the mean W-I variations for serum creatinine (5.8%) and cystatin C (5.4%) were both much lower than the W-I variation of creatinine clearance (18.7%). As expected, the MDRD GFR had a similar W-I variation (6.7%) to that of serum creatinine and its values were markedly different than GFR by creatinine clearance. On the 15 sets of frozen samples, the W-I variation of creatinine measured by the enzymatic method (CV 5.2%) was slightly less than by the picrate method (CV 6.2%). CONCLUSIONS: The low W-I variation of both serum cystatin C and serum creatinine suggests that serial measurements of either would detect a changes in renal function earlier than would GFR by creatinine clearance or MDRD equation, which allows reporting only for GFRs<60 ml/min/1.7 m(2). While we measured only creatinine clearance, the large variability, difficulty, and cost of all clearance measurements make them impractical for routine monitoring of patients.