Evaluation of renal function in intensive care: plasma cystatin C vs. creatinine and derived glomerular filtration rate estimates.

Plasma cystatin C, a new marker of glomerular filtration rate (GFR), was prospectively evaluated in surgical intensive care. Cystatin C was measured (immunonephelometry, Dade-Behring) in 10 patients selected to cover a full range of GFR (phase I) and in 28 unselected consecutive patients followed for 5 days post-admission (phase II). Results were compared with (51)Cr-EDTA clearance (phase I only), plasma creatinine (kinetic Jaffe, Roche), 24-h or estimated by Cockcroft and Gault (CG) creatinine clearance (CrCl), and modified diet in renal disease (MDRD)-estimated GFR. In phase I, the highest correlation with(51)Cr-EDTA clearance (22-198 mL/min) was noted for CG CrCl (r(2): 0.883, p<0.001). During phase II follow-up, 24-h CrCl could not be calculated in 25% of daily evaluations. Cystatin C correlated with creatinine (0.856, p<0.0001) and CG CrCl with MDRD GFR (0.926, p<0.0001) in renal failure (10-78 mL/min, n=60). There was a +40% (p<0.001) median difference between cystatin C and creatinine (as a % of upper normal cut-off). Sensitivity/specificity to detect a <80 mL/min CG CrCl was 88/97% for cystatin C vs. 48/100% for creatinine (laboratory cut-off). In patients with normal and stable renal function (n=14), day-to-day intra-individual variation was 7.4% for cystatin C (vs. 10.6% for creatinine). In intensive care unit surgical adult patients, CG CrCl provides an easy and cost-effective estimate of GFR. Superior to creatinine, plasma cystatin C can be measured in selected patients where CG CrCl is known to be inaccurate.     

Cystatin C and estimates of renal function: searching for a better measure of kidney function in diabetic patients

BACKGROUND: Early identification of impairment in renal function is crucial in diabetic patients. Serum cystatin C may be the most sensitive indicator of glomerular filtration rate (GFR) in the clinical setting. METHODS: We compared cystatin C with creatinine, the Cockcroft-Gault (C-G) formula, and the Modification of Diet in Renal Disease (MDRD) study equation for the assessment of early decreased renal function in 288 diabetic patients (125 type 1, 163 type 2) with renal impairment [GFR: 4-222 mL x min(-1) x (1.73 m(2))(-1)]. Relationships of cystatin C, creatinine, and iohexol clearance were linearized by plotting their reciprocals in a simple regression model. Diagnostic efficiency was calculated from ROC curves. RESULTS: In this study population, cystatin C (P = 0.0013) was better correlated with GFR (r = 0.857) than were creatinine (r = 0.772), C-G (r = 0.750), and MDRD (r = 0.806), a result replicated in patients with normal renal function (P = 0.023, type 1; P = 0.011, type 2), but not in those with decreased GFR. Mean cystatin C concentrations showed step-by-step statistically significant increases as GFR decreased, allowing very early detection of reduction in renal function. At 90 mL x min(-1) x (1.73 m(2))(-1) and 75 mL x min(-1) x (1.73 m(2))(-1) cut-points, diagnostic efficiencies of cystatin C (89% and 92%) were better than those of the other variables (79%-82% and 85%-86%, respectively; P = 0.01). CONCLUSIONS: All data supported the value of serum cystatin C compared with conventional estimates based on serum creatinine measurement for detecting very early reduction of renal function. Use of cystatin C to measure renal function will optimize early detection, prevention, and treatment strategies for diabetic nephropathy.     

Relationships among serum cystatin C, serum creatinine, lean tissue mass and glomerular filtration rate in healthy adults

In an effort to increase our knowledge of the optimal use of serum cystatin C and creatinine as glomerular filtration rate (GFR) markers, these variables, as well as lean tissue mass and GFR, were determined in a population of 42 healthy young adults (men and women with normal GFR). Dual-energy X-ray absorptiometry and measurement of the plasma clearance of iohexol were used to measure lean tissue mass and GFR, respectively. Serum creatinine was significantly correlated to lean tissue mass (r=0.65; p < 0.0001) but not to GFR (1/creatinine vs. GFR: r=0.11; p=0.106). In contrast, serum cystatin C correlated with GFR (1/cystatin C vs. GFR: r=0.32; p=0.0387), especially in men (1/cystatin C vs. GFR: r=0.64; p=0.0055), but not to lean tissue mass. These results might explain previous observations that serum cystatin C seems to be a better marker for GFR than serum creatinine, particularly for individuals with small to moderate decreases in GFR. However, the results also show that the serum concentrations of both creatinine and cystatin C are determined not only by GFR, but also by other factors. Since these additional factors differ for cystatin C and creatinine, it seems justified to use serum creatinine and cystatin C in conjunction to estimate GFR, at least until it is known in what situations serum creatinine or cystatin C is the preferable marker.     

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.     

光抑素C与血肌酐对2型糖尿病患者肾小球滤过功能评价比较

目的 比较光抑素C(Cystatin C)和血清肌酐及8小时肌酐清除率，评价其对2型糖尿病患者肾小球滤过率(GFR)的判断价值。方法 选择80例2型糖尿病患者，检测其血肌酐、肌酐清除率、尿微量白蛋白排泌率(UAER)及Cystatin C水平，同时通过^99mTc-DTPA排泌率，应用Gates法计算GFR。结果 Cystatin C水平随GFR下降逐渐升高。相关性分析示Cystatin C与GFR呈相关性(r=-0．663，p=0．000)，明显高于肌酐(r=-0．444，P=0．009)及8小时肌酐清除率(r=0．300，P=0．000)。ROC曲线分析示Cystatin C具有更大的曲线下面积(AUC)，敏感性(82％)、特异性(96％)均好，而肌酐特异性好(98％)、敏感性差(20％)，8小时肌酐清除率敏感性(68％)、特异性(79％)均不理想。Cystatin C诊断精确性(80％)明显高于肌酐(63％)。结论 Cystatin C是反映GFR的更敏感指标，可更早、更准确地反映2型糖尿病患者GFR的变化。     

Relationships among serum cystatin C,serum creatinine,lean tissue mass and glomerular filtration rate in healthy adults

In an effort to increase our knowledge of the optimal use of serum cystatin C and creatinine as glomerular filtration rate (GFR) markers, these variables, as well as lean tissue mass and GFR, were determined in a population of 42 healthy young adults (men and women with normal GFR). Dual­energy X­ray absorptiometry and measurement of the plasma clearance of iohexol were used to measure lean tissue mass and GFR, respectively. Serum creatinine was significantly correlated to lean tissue mass (r=0.65; p&lt;0.0001) but not to GFR (1/creatinine vs. GFR: r=0.11; p=0.106). In contrast, serum cystatin C correlated with GFR (1/cystatin C vs. GFR: r=0.32; p=0.0387), especially in men (1/cystatin C vs. GFR: r=0.64; p=0.0055), but not to lean tissue mass. These results might explain previous observations that serum cystatin C seems to be a better marker for GFR than serum creatinine, particularly for individuals with small to moderate decreases in GFR. However, the results also show that the serum concentrations of both creatinine and cystatin C are determined not only by GFR, but also by other factors. Since these additional factors differ for cystatin C and creatinine, it seems justified to use serum creatinine and cystatin C in conjunction to estimate GFR, at least until it is known in what situations serum creatinine or cystatin C is the preferable marker.     

Calculation of glomerular filtration rate expressed in mL/min from plasma cystatin C values in mg/L

The Cockcroft Gault formula is often used to calculate the glomerular filtration rate (GFR) from plasma creatinine results. In Sweden this calculation is not usually done in the laboratory, but locally in the wards. These manual calculations could cause erroneous results. In several studies plasma cystatin C has been shown to be superior to plasma creatinine for estimation of GFR. One limitation of using cystatin C as a GFR marker is that there is no conversion formula transforming cystatin C expressed as mg/L to GFR expressed as mL/min. In this study plasma creatinine and cystatin C were compared with iohexol clearance. A stronger correlation (p < 0.0001) was found between cystatin C and iohexol clearance (r2 = 0.91) than between creatinine and iohexol clearance (r2 = 0.84). From the correlation data a formula was calculated to convert cystatin C expressed as mg/L to GFR (mL/min). The formulas y = 77.24x(-1.2623) (Dade Behring cystatin C calibration) or y = 99.43x(-1.5837) (DakoCytomation cystatin C calibration) are used to calculate GFR expressed in mL/min from the cystatin C value in mg/L and both results are reported to the referral doctor. These formulas can provide the clinicians with reliable and readily available GFR data based on single measurements of cystatin C concentrations.     

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.     

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     

Evaluation of serum cystatin C and chromogranin A as markers of nephropathy in patients with type 2 diabetes mellitus

Nephropathy is a significant cause of morbidity and mortality in patients with diabetes mellitus (DM). The condition is characterized by persistent albuminuria and years of progressive renal structural changes associated with decline in the glomerular filtration rate (GFR). This study evaluates whether serum concentrations of the endogenous markers of GFR, cystatin C and chromogranin A could be used as indicators of nephropathy in 77 patients with Type 2 DM. On the basis of early morning urine microalbumin:creatinine ratio, patients were divided into patients without diabetic nephropathy (DN) who were normoalbuminuric (n = 27) and patients with DN who were microalbuminuric (n = 8) or macroalbuminuric (n = 42). Patients with reduced GFR or elevated serum cystatin C did not show the expected increase in serum chromogranin A. Twenty-six percent of the patients with normoalbuminuria and 6% of those with DN had serum chromogranin A below the detection limit of the assay (< 2 U/L). In patients with DN, serum chromogranin A showed significant correlation with serum cystatin C, but not with serum creatinine and creatinine clearance. Serum cystatin C and creatinine showed poor correlation with duration of DM and HbA1c. Serum cystatin C and creatinine were significantly higher in patients with DN than in normoalbuminuric patients. Serum cystatin C showed significant correlation with serum creatinine (rs = 0.45, p = 0.002), but not with creatinine clearance (rs = 0.23, p = 0.17) in patients with DN. Four of nine patients with creatinine clearance between 50 and 80 mL/min had increased (> or = 1.4 mg/L) serum cystatin C compared with only two patients with increased serum creatinine concentration. Twenty of 50 (40%) patients with DN had elevated serum cystatin C compared with 6 of 50 (12%) with elevated serum creatinine. If microalbuminuria is regarded as the "gold-standard" test, serum cystatin C has a sensitivity of 40% and specificity of 100% for the detection of DN. However, further studies are required to confirm the usefulness of serum cystatin C estimation as a screening test and as an early indicator and predictor of the development of DN.     

肾病患者内源性肾小球滤过率的实验室评价

目的 :评估肾病患者内源性肾小球滤过率 (GFR)。方法 :测定了 5 7例肾病患者和 39例健康对照血中CystatinC(CysC )、尿素、肌酐和肌酐清除率浓度。结果 :患者尿素、肌酐、肌酐清除率和CysC浓度与健康对照组间均存在明显差异 (P <0 .0 0 1 ) ;相关分析表明CysC和肌酐清除率之间 (P <0 .0 1 )、CysC和肌酐之间 (P <0 .0 1 )存在明显的相关关系。而肌酐和尿素之间 (P >0 .0 5 ) ,以及肌酐和肌酐清除率之间 (P >0 .0 5 )无明显相关关系存在。结论 :肾病患者血中CysC浓度增高 ,对GFR功能早期受损的评估优于尿素、肌酐和肌酐清除率。     

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.     

胱抑素C对恶性肿瘤患者化疗过程中评价早期肾功能损伤的临床意义

目的探讨血清胱抑素C(Cys C)在恶性肿瘤患者化疗过程中对肾脏功能早期损伤评价的临床应用。方法对78例恶性肿瘤患者化疗前后以及52例正常对照者血清进行血清胱抑素C(Cys C)、肌酐(CREA)测定。结果肿瘤患者化疗前、后(以第1个疗程计算)CysC水平分别为(0.78±0.31)mg/L,(1.30±0.22)mg/L;正常对照(0.62±0.35)mg/L。肿瘤患者化疗后血清CysC水平均明显高于对照组(P<0.05),且肿瘤患者化疗后的血清CysC水平也明显高于化疗前(P<0.05)。化疗前后Cys C的异常检出率明显高于CREA的异常检出率,两者比较具有显著性差异(P<0.05)。结论血清Cys C检测在反映肿瘤化疗患者肾功能早期损害中有很好的临床参考价值。     

Tissue lipid peroxidation and antioxidant status in patients with adenocarcinoma of the breast

BACKGROUND: The results obtained for serum cystatin C, which has been proposed as a novel marker of glomerular filtration rate (GFR), in kidney and liver transplant are still very limited. In our study, the relationship between serum cystatin C and creatinine in kidney and liver transplant patients was investigated. METHODS: Serum cystatin C and creatinine concentrations were determined in 182 samples from 52 kidney transplant patients and 71 samples from 28 liver transplant patients at 1-9870 days post-transplantation time. Eighty-seven serum samples from 66 patients with different types of chronic kidney disease were also analysed. RESULTS: The serum creatinine (r=-0.517, p<0.001) and cystatin C (r=-0.409, p<0.001) concentrations were negatively correlated with the post-transplantation time in the kidney transplant patients. In the liver transplant patients, the correlation between these variables is not statistically significant. The creatinine/cystatin C ratio in the liver transplant group is significantly lower than in the other group of patients (p<0.001). This ratio in the kidney transplant patients groups is significantly lower than in the kidney disease group (p<0.001). In the kidney transplant patients the creatinine/cystatin C ratio and the post-transplantation time were negatively correlated (r=-0.523, p<0.001); however, in the liver transplant patients the correlation between these variables was not significant. CONCLUSIONS: In the groups of kidney disease and kidney transplant patients, as renal function decreases, there is an increase in the creatinine/cystatin C ratio. This may be due to the fact that, since creatinine is eliminated by glomerular filtration and tubular secretion, as renal function is impaired, its serum concentration increases to a greater extent than that of cystatin C, which is only eliminated by glomerular filtration. In the liver transplant patients, the creatinine/cystatin C ratio is lower than in the other groups. This may be due to better preserved renal function, lower muscular mass and a reduced rate of creatine formation and creatinine production in some of these patients. The serum cystatin C would be a better GFR marker than the widely used creatinine in liver transplant patients.     

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.     

血清胱抑素C判断移植肾功能的研究

目的:探讨血清胱抑素C(cystatin C)在监测移植肾功能中的价值.方法:23例肾移植患者采用颗粒强透免疫比浊法测定血清cystatin C,同时采用同位素锝[99mTc]-二乙烯三胺五乙酸(diethylenetriaminepentaacetic acid,DTPA)肾动态显像测定移植肾小球滤过率(glomerular filtration rate,GFR),测定血清肌酐(serum creatinine,Scr)及用公式计算内生肌酐清除率(endogenous creatinine clearance,Ccr).测定34名正常健康者作为对照.采用SPSS11软件分析各指标相关性及特异度、灵敏度.结果:cystatin C、Scr、Ccr与GFR的相关性分别是r1 =-0.872(P＜0.001)、r2=-0.687(P＜0.001)、r3=0.634(P=0.002).在判断GFR是否受损时,cystatin C的特异度和灵敏度(100%,94.1%)明显高于Scr(75.0%,70.6%)和Ccr(75.0%,88.2%);在判断肾功能轻度受损时,cystatin C的特异度和灵敏度(100%,88.9%)也比Scr(83.3%,66.7%)和Ccr(83.3%,77.8%)高;尽管在判断肾功能重度受损时,cystatin C的灵敏度(75%)不如Scr(100%),但特异度(100%)仍高于Ccr(88.2%).结论:cystatin C能准确判断移植肾功能,优于Scr和Ccr,具有临床应用价值.     

Plasma concentrations of cystatin C in patients with coronary heart disease and risk for secondary cardiovascular events: more than simply a marker of glomerular filtration rate

BACKGROUND: Renal impairment (RI) is associated with worse prognosis. Recently, cystatin C has been shown to represent a potentially superior marker of the glomerular filtration rate compared with creatinine clearance (CrCl). We evaluated the impact of cystatin C and other markers of RI on prognosis in a large cohort of patients with coronary heart disease (CHD). METHODS: Cystatin C, creatinine (Cr), and CrCl were determined at baseline in a cohort of 1033 patients (30-70 years) with CHD. Patients were followed for a mean of 33.5 months, and a combined endpoint [fatal and nonfatal cardiovascular disease (CVD) events] was used as the outcome variable. Cystatin C was measured by immunonephelometry, and CrCl was calculated. RESULTS: During follow-up, 71 patients (6.9%) experienced a secondary CVD event. Neither Cr (P = 0.63) nor CrCl (P = 0.10) were associated with incidence of CVD events, whereas cystatin C was clearly associated with risk of secondary CVD events (P <0.0001). In multivariate analyses, patients in the top quintile of the cystatin C distribution at baseline had a statistically significantly increased risk of secondary CVD events even after adjustment for classic risk factors, severity of coronary disease, history of diabetes mellitus, treatment with angiotensin-converting enzyme inhibitors, and C-reactive protein (hazard ratio, 2.27; 95% confidence interval, 1.05-4.91) compared with patients in the bottom quintile. CONCLUSIONS: These data support the possibly important prognostic value of cystatin C among patients with known CHD and suggest that it may be a useful clinical marker providing complementary information to established risk determinants.     

血清半胱氨酸蛋白酶抑制剂C检测对肿瘤化疗患者早期肾损伤的诊断意义

目的探讨血清半胱氨酸蛋白酶抑制剂C(CysC)在肿瘤化疗患者早期肾功能损伤诊断的临床应用价值。方法以56例健康体检人员为对照,比较96例不同肾功能损伤的肿瘤化疗患者CysC、肌酐(Cr)的检测情况,并进行统计学分析。结果肾小球滤过率(GFR)、CysC,肿瘤中各组与对照组比较均有统计学差异(P<0.05);肾功能轻度受损组、肾功能不全组与肿瘤肾功能正常组比较均有统计学差异(P<0.05);Cr肿瘤肾功能正常组与对照组比较无统计学差异(P>0.05),肾功能轻度受损组与肾功能正常组比较无统计学差异(P>0.05);CysC(r=-0.835,P<0.001)、Cr(r=-0.642,P<0.001)与GFR均呈负相关;方法学指标评价CysC各项指标[灵敏度、特异度、正确诊断指数、符合率、阴(阳)性预测值]均优于Cr。结论 CysC对肿瘤化疗患者早期肾功能损伤的监测更具参考价值。     

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.     

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。