The diagnostic value of human epididymis protein 4 as a novel biomarker in patients with renal dysfunction

Purpose

In this study, we investigated the diagnostic value of human epididymis protein 4 (HE4) in acute and chronic renal dysfunction and analyzed the correlation between HE4 levels and the results of routine renal function tests. We aimed to provide evidence to establish HE4 as a novel biomarker of renal injury and its appropriate application as a marker of ovarian cancer.

Methods

We collected 259 serum samples from hospitalized patients with different causes of renal damage. HE4 serum levels were detected by chemiluminescence and the levels of serum creatinine, urea, and cystatin C were tested by conventional clinical chemical methods.

Results

The levels of HE4 were highest in the acute kidney injury groups and chronic kidney disease groups, although other groups were also significantly higher than the control group. HE4 and creatinine, urea, and cystatin C had a positive linear correlation. In contrast, HE4 and estimated glomerular filtration rate (eGFR) had a negative linear correlation, with a correlation coefficient of ??0.674 (P?<?0.01). Area under the receiver-operating characteristic curve analysis showed that HE4 has higher diagnostic value compared with creatinine, urea, and cystatin C in both acute and chronic renal injury patients; however, HE4 and creatinine have a similar diagnostic value. Notably, HE4 concentration gradually increased with a decline of glomerular filtration rate, with significant differences evident between different eGFR stages.

Conclusion

HE4 is a potential biomarker of kidney injury in acute and chronic renal dysfunction. Importantly, clinicians should be aware of this when using HE4 to diagnose ovarian cancer.

     

Comparison of serum cystatin C and creatinine changes after cardiopulmonary bypass in patients with normal preoperative kidney function

Purpose

Serum creatinine is used ubiquitously to estimate glomerular filtration rate and to diagnose acute kidney injury after cardiac surgery. Serum cystatin C is a novel biomarker that has emerged as a possible diagnostic alternative to serum creatinine. It is unclear if the dynamic changes in serum cystatin C immediately following cardiopulmonary bypass (CPB) differ from those of serum creatinine in patients with normal preoperative kidney function.

Methods

We compared changes in serum levels of creatinine and cystatin C by measuring them serially in 19 patients undergoing CPB. Within-patient differences for serum creatinine and serum cystatin C were compared by repeated measures ANOVA.

Results

Serum creatinine and cystatin C levels showed significant correlation with each other. Both biomarkers showed a significant decrease after CPB, but their serum concentrations reverted to pre-CPB levels within 12 h. Serum levels of serum creatinine remained unchanged from baseline levels throughout 72-h post-CPB. In contrast, serum cystatin C levels rose further and became significantly higher compared to baseline within 48 h. Serum cystatin C remained significantly elevated at 48- and 72-h post-CPB.

Conclusions

Processes that determine the serum concentrations of serum creatinine and cystatin C in the post-CPB period affect the two biomarkers differently, suggesting that the two are not interchangeable as diagnostic markers of glomerular filtration rate. Future studies are needed to examine if these discrepancies are related to differences in their production rates, in their ability to detect small changes in glomerular filtration rate, or to a combination of these, and to determine the effect of such differences on the diagnostic and prognostic accuracy of the two biomarkers.     

Neutrophil Gelatinase-Associated Lipocalin and Cystatin C Could Predict Renal Outcome in Patients Undergoing Kidney Allograft Transplantation: A Prospective Study

Urinary neutrophil gelatinase-associated lipocalin (NGAL) may represent an early, predictive biomarker of delayed graft function due to ischemia-reperfusion injury. Unfortunately, creatinine is an unreliable indicator of acute changes in kidney function. NGAL was proposed as a novel early marker for detection of acute renal failure. Therefore, the aim of the study was to assess whether NGAL and cystatin C predicted outcomes among 41 consecutive patients undergoing kidney transplantation. Serum NGAL and cystatin C were evaluated before, as well as 1, 3, 6, and 10 days after kidney transplantation using commercially available kits. Serum creatinine was assessed at each time. We observed a significant fall in serum NGAL as early as 1 day following kidney transplantation. Serum cystatin C decreased significantly 3 days after transplantation. Before transplantation, serum NGAL was related to creatinine and cystatin C. At each time point, serum NGAL was related positively to serum creatinine, cystatin C, and negatively to urine volume. In patients with delayed graft function, there was no fall in serum NGAL or cystatin C. Our findings may have important implications for the clinical management of patients undergoing kidney transplantation. The “window of opportunity” to distinguish between acute rejection and calcineurin inhibitor nephrotoxicity is narrow in delayed graft function. Time is limited to introduce proper treatment after the initiating insult. Therefore, NGAL needs to be investigated as a potential early marker for delayed graft function, especially in the settings of early dialysis treatment or antirejection therapy.     

Molecular markers of kidney injury

Renal dysfunction is common in urologic patients, especially in those undergoing nephrectomy for renal cancer. Partial nephrectomy better preserves renal function than radical nephrectomy, but is associated with acute kidney injury related to loss of nephrons and ischemic injury. Ischemic injury may not be reliably assessed using common clinical parameters, such as serum creatinine and urine output, which may delay detection of clinically-significant kidney damage. Molecular markers, such as cystatin C, neutrophil gelatinase-associated lipocalin (NGAL), IL-18 and kidney injury molecule-1 (KIM-1), better quantify the extent of acute ischemic and/or tubular injury than other currently available tools. The use of these and/or other markers may facilitate research to improve outcomes following partial nephrectomy.     

Early detection of acute renal failure by serum cystatin C

BACKGROUND: Acute renal failure (ARF) is associated with high mortality. Presently, no specific therapy for ARF exists. Therefore, early detection of ARF is critical to prevent its progression. However, serum creatinine, the standard marker to detect ARF, demonstrates major limitations. We prospectively evaluated whether serum cystatin C detected ARF earlier than serum creatinine. METHODS: In 85 patients at high risk to develop ARF, serum creatinine and cystatin C were determined daily. ARF was defined according to the Risk of renal dysfunction, Injury to the kidney, Failure of kidney function, Loss of kidney function, and ESRD (RIFLE) classification when creatinine increased by >/=50% (R-criteria), by >/=100% (I-criteria), or by >/=200% (F-criteria). In analogy, ARF was detected when cystatin C increased by >/=50%, by >/=100%, or by >/=200%. RESULTS: Forty-four patients developed ARF and 41 served as controls. In ARF by R-, I-, and F-criteria, the increase of cystatin C significantly preceded that of creatinine. Specifically, serum cystatin C increased already by >/=50% 1.5 +/- 0.6 days earlier compared to creatinine. Serum cystatin C demonstrated a high diagnostic value to detect ARF as indicated by area under the curve of the ROC analysis of 0.82 and 0.97 on the two days before the R-criteria was fulfilled by creatinine. Cystatin C detected ARF according to the R-criteria with a sensitivity of 55% and 82% on these days, respectively. Cystatin C also performed excellently, detecting ARF defined by the I- and F-criteria two days prior to creatinine, and moderately well predicting renal replacement therapy in the further course of ARF. Additionally, low T(3)- or T(3)/T(4) syndrome, glucocorticoid deficiency and excess did not affect cystatin C levels, adding to its usefulness in critically ill patients with ARF. CONCLUSION: Serum cystatin C is a useful detection marker of ARF, and may detect ARF one to two days earlier than creatinine.     

Evaluation of the renal function in cardiac surgery with CPB: role of the cystatin C and the calculated creatinine clearance

Objectives

The evaluation of the renal function in cardiac surgery is difficult. The gold standard remains the creatinine clearance in clinical practice. Cystatin C was recently proposed in order to evaluate the renal function. The aim of our study was to evaluate the cystatin C in cardiac surgery with CPB.

Patients and methods

After informed consent and ethical committee agreement, 60 patients operated in cardiac surgery with CPB were prospectively included. Cystatin C,measured and calculated (Cockcroft and MDRD methods) creatinine were compared with the Student t-test and with the Bland and Altman method. p < 0,05 was considered as a significant threshold.

Results

The reproducibility of the calculated creatinine clearance was better when the urinary collecting time was below 400 minutes. The estimation of the creatinine clearance by the Cockcroft and MDRD methods is better when the clearance is low. A significant correlation between the creatinine clearance and the cystatin C does exist, but the correlation coefficient was low. In case of acute renal dysfunction, the increase of the creatinine occurred earlier than the increase of the cystatin C.

Conclusion

In cardiac surgery with CPB, the evaluation of the renal function was not improved by the cystatin C.     

The challenges of assessing acute kidney injury in infants

Definitions of pediatric acute kidney injury (AKI) use changes of serum creatinine. There is a paucity of well-designed studies in infants because of creatinine age-dependency. The emerging role of cystatin C as a superior marker of renal dysfunction led to a carefully conducted study on AKI in infants by Zappitelli et al. This Commentary calls for the development of age-independent serum creatinine and estimated glomerular filtration rate z scores.     

Serum neutrophil gelatinase-associated lipocalin as a marker of renal function in hypertensive and normotensive patients with coronary artery disease

Aim: Hypertension is one of the risk factors for cardiovascular diseases. The kidneys could be a victim and/or culprit of hypertension. Recently, the value of neutrophil gelatinase‐associated lipocalin (NGAL) was highlighted as a novel marker for early detection of acute renal damage. Therefore, the aim of the study was to assess whether hypertension could affect NGAL and cystatin C levels in patients with normal serum creatinine (lower than 1.5 mg/dL in males and 1.2 mg/dL in females) and stable coronary artery disease. Methods: Serum, urinary NGAL, cystatin C and estimated glomerular filtration rate (eGFR; Modification of Diet in Renal Disease study (MDRD) and Cockcroft–Gault formulas) were evaluated in hypertensive, normotensive patients with stable coronary heart disease and healthy volunteers. Results: Normotensives had significantly lower NGAL than hypertensives. Serum cystatin C was significantly lower in normotensives than in hypertensives. Urinary NGAL did not differ significantly between these groups. Despite similar serum creatinine levels, eGFR (MDRD and Cockcroft–Gault formulas) was significantly higher in normotensives than in hypertensives. Serum NGAL was related, in univariate analysis, to serum creatinine, urea, urinary NGAL, haemoglobin, haematocrit, duration of hypertension, age, eGFR by MDRD and Cockcroft–Gault, and cystatin C. Conclusion: Hypertension is associated with kidney injury as reflected by elevated serum NGAL and cystatin C. It is noteworthy that despite normal serum creatinine, eGFR is relatively low suggesting impaired renal function. Therefore, NGAL needs to be investigated as a potential early marker for impaired kidney function/kidney injury, especially in patients with another risk factor for kidney damage, namely coronary artery disease.     

Glomerular Filtration Rate Estimation in Prospective Living Kidney Donors: Preliminary Study

Introduction

Kidney transplantation prolongs life expectancy in end-stage renal disease patients at a lesser cost than dialysis. Estimation of kidney function is crucial in the evaluation of prospective living kidney donors. Although unsurpassed in their precision methods of glomerular filtration rate (GFR) measurement with exogenous substances are invasive, expensive, and carry a risk for anaphylactic reactions. Alternatively, kidney function can also be assessed by GFR estimation formulas based on serum creatinine or novel markers such as cystatin C or β-trace protein (BTP). The aim of this study was to compare the performance of GFR estimation methods with reference scintigraphy-measured GFR in population of living kidney donor candidates.

Methods

We included 25 prospective kidney donors (aged 28–64 years) and measured GFR with the following equations: Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD), Mayo Clinic, Nankivell, Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI; including cystatin C), and BTP based. GFR were assessed by ⁹⁹mTc-DTPA for reference. All estimation methods were compared with a reference by general linear models.

Results

The precision of GFR estimation by all methods is unsatisfactory (30% margin of reference held in <50% of cases). Direction of regression coefficients is negative for some of the methods even when adjusted for body mass index (BMI). Of the study subjects, 64% were overweight/obese. BMI value is significantly correlated with measured GFR (P < .01). CKD-EPI estimation equations are the most precise methods of GFR estimation in this analysis; in addition, CKD-EPI cystatin C and combined creatinine/cystatin C estimators are robust to overweight/obesity.

Conclusions

The precision of GFR estimation is unsatisfactory, in part because of overweight, which adversely influences measured GFR, but also renders estimation methods unusable, except for CKD-EPI cystatin C and combined creatinine/cystatin C formulae. GFR measurement with exogenous substances remains the method of choice in the assessment of kidney function in prospective kidney donors. In addition, it provides useful information on differential (split) renal function.     

Pretransplantation Cystatin C,but not Creatinine,Predicts 30-day Cardiovascular Events and Mortality in Liver Transplant Recipients With Normal Serum Creatinine Levels

Background

The connection between renal dysfunction and cardiovascular dysfunction has been consistently shown. In patients with liver cirrhosis, renal dysfunction shows a tight correlation with prognosis after liver transplantation (LT); therefore, precise renal assessment is mandatory. Cystatin C, a sensitive biomarker for assessing renal function, has shown superiority in detecting mild renal dysfunction compared to classical biomarker creatinine. In this study, we aimed to compare cystatin C and creatinine in predicting 30-day major cardiovascular events (MACE) and all-cause mortality in LT recipients with normal serum creatinine levels.

Predicting kidney disease progression in patients with acute kidney injury after cardiac surgery

Objective

The study objective was to identify patients who are likely to develop progressive kidney dysfunction (acute kidney disease) before their hospital discharge after cardiac surgery, allowing targeted monitoring of kidney function in this at-risk group with periodic serum creatinine measurements.

血清胱抑素C和尿微量白蛋白联合检测在人类免疫缺陷病毒感染者肾功能损伤检测中的应用价值

目的评估血肌酐和尿常规的常规检测基础上联合血清胱抑素C和尿微量白蛋白检测在人类免疫缺陷病毒（HIV）感染者肾功能损伤检测中的应用价值。 方法以2019年2～5月于首都医科大学附属北京地坛医院感染一科住院的169例HIV感染者为研究对象，完善其尿常规、尿微量白蛋白、血肌酐、血清胱抑素C检测；分析尿蛋白及尿微量白蛋白的阳性检出率及其差异，血肌酐升高及血清胱抑素C升高的比例及其差异。计算应用替诺福韦酯（TDF）及合并丙型肝炎、高血压、糖尿病、肿瘤的肾功能损伤的相对危险度。 结果169例HIV感染者中尿常规示尿蛋白阳性者5例（3.0%），尿微量白蛋白升高者17例（10.1%），两者阳性检出率差异具有统计学意义（χ² = 5.9、P = 0.007）。血肌酐升高者10例（5.9%），血清胱抑素C升高者20例（11.8%），两者阳性检出率差异具有统计学意义（χ² = 3.0、P = 0.042）。在尿常规和血肌酐检测的基础上联合检测尿微量白蛋白和血清胱抑素C的总体阳性检出率为49例（30.0%）。CD4⁺ T淋巴细胞计数< 200个/μl与≥ 200个/μl组患者血清胱抑素C水平分别为0.94（0.83，1.05）mg/L、0.85（0.77，0.95）mg/L，差异具有统计学意义（Z =-3.02、P = 0.003）。应用TDF及合并丙型肝炎、高血压、糖尿病、肿瘤的肾功能损伤的相对危险度分别为1.1、1.5、1.9、2.2和1.4。 结论HIV感染者中，单纯以尿常规为依据评估有无蛋白尿，以血肌酐水平为依据评估肾小球滤过功能会低估肾功能损伤的患病率。在常规检测血肌酐和尿常规的基础上联合检测血清胱抑素C和尿微量白蛋白在提高HIV感染者肾功能损伤检出率方面具有重要的应用价值。低CD4⁺ T淋巴细胞计数、应用TDF及合并丙型肝炎、高血压、糖尿病、肿瘤均为肾功能损伤的危险因素。     

Cystatin C does not detect acute changes in glomerular filtration rate in early diabetic nephropathy

BACKGROUND: The measurement of renal functional reserve (acute change in glomerular filtration rate [GFR] after protein load) allows the detection of sub-clinical renal dysfunction and has prognostic implications in diabetes. Our aim was to test cystatin C as an index of GFR and renal functional reserve. METHODS: GFR was measured by C(Sinistrin) at baseline and after protein load in 28 diabetic patients with serum creatinine <1.2 mg/dL. The C(Sinistrin) was compared with cystatin C, serum creatinine, creatinine clearance, and Cockcroft-Gault formula. RESULTS: Baseline C(Sinistrin) ranged from 67-172 mL/min. Regression analysis showed an overall low relationship between C(Sinistrin) and the indirect markers of GFR. The highest correlation with C(Sinistrin) was obtained for cystatin C clearance (R(2) = 0.58, r = 0.76, p < 0.001), the 1/serum cystatin C (R(2) = 0.58, r = 0.76, p < 0.001), and serum cystatin C (R(2) = 0.52, r = 0.72, p < 0.001). Renal functional reserve was preserved in 6 of 28 patients. There was no significant change in cystatin C in response to protein load. CONCLUSION: Wide variation in baseline GFR emphasizes the need for the early detection of renal dysfunction. Cystatin C correlated best with C(Sinistrin) at baseline, but did not detect renal functional reserve.     

The discrepancy between serum creatinine and cystatin C can predict renal function after treatment for postrenal acute kidney injury: multicenter study and pooled data analysis

Background

Although serum cystatin C and creatinine are used as practical markers of renal function, the discrepancy between them in postrenal acute kidney injury (AKI) cases was reported. The aim of this study was to determine whether the preoperative serum cystatin C (pre-CysC) level could predict clinical outcomes after treatment in patients with postrenal AKI.

Methods

Patients who underwent urological interventions with postrenal AKI were enrolled in this prospective observational study. Associations among preoperative serum creatinine (pre-sCr), pre-CysC, and nadir postoperative serum creatinine (post-sCr) were evaluated. In addition, based on our results in combination with detailed data from the literature, a predictive equation for postoperative serum creatinine (post-sCr) was developed by simple regression analysis and validated using Bland–Altman plots.

Results

Finally, 19 patients were eligible for analysis in this study. The value calculated by subtracting pre-CysC (mg/L) from pre-sCr (mg/dl) had a strong correlation to the decrement of serum creatinine (r?=?0.9508, p?<?0.0001). We added the data of 16 patients obtained from the literature to our series, which were totally randomized into 2 groups, training set and validation set in a 2:1 ratio (n?=?23 and 12, respectively) to develop and validate a predictive equation for post-sCr. The mean difference between the predictive and actual post-sCr, ?0.68 mg/dl (95% CI ?1.62 to 0.26) in the validation set was within the limits of agreement.

Conclusion

We showed that the discrepancy between pre-sCr and pre-CysC could predict improvement of renal function after intervention in patients with postrenal AKI.

     

Discrepancy between serum levels of low molecular weight proteins in acute kidney injury model rats with bilateral ureteral obstruction and bilateral nephrectomy

Background  

Serum levels of low molecular weight (LMW) proteins, such as cystatin C and beta-2-microglobulin (MG), are used as GFR markers. Ureteral obstruction is a cause of acute kidney injury (AKI). However, it is unclear whether serum concentrations of LMW proteins are increased in postrenal AKI like in intrinsic AKI. To evaluate this question, the responses of serum levels of cystatin C and beta-2-MG were investigated in rats with bilateral ureteral obstruction (BUO) and bilateral nephrectomy (BNX).     

胱抑素C在缺血／再灌注急性肾损伤大鼠尿液中的变化及意义

目的：检测肾缺血/再灌注大鼠尿液胱抑素C含量,探讨其在缺血/再灌注急性肾损伤早期评估中的作用。方法：选取雄性SD大鼠,随机分为4组,建立缺血/再灌注急性肾损伤动物模型,缺血时间4组分别为0、10、20、30min,测定各组大鼠术前及再灌注24h后尿液胱抑素C,血清肌酐（Scr）、尿素氮（BUN）浓度,计算24h肌酐清除率（Ccr）,取各组再灌注24h后肾组织作组织学检查,行肾小管坏死半定量评分。结果：各组大鼠基线肾功能差异无统计学意义,再灌注24h后与基线值相比,肾缺血0min组及10min组BUN、Scr及Ccr无显著改变;肾缺血20min组BUN、Scr无显著改变,但Ccr显著降低;肾缺血30min组BUN[（45.3±14.6）vs（13.8±1.6）mmol/L]、Scr[（160.8±22.2）vs（36.9±7.9）μmol/L]显著升高,Ccr显著降低[（1.87±0.3）vs（0.56±0.1）ml/min]。20min组及30min组肾小管坏死评分与0min组相比显著升高。再灌注24h后与基线值相比,肾缺血0min组尿液胱抑素C水平无显著改变,肾缺血10min[（0.79±0.11）vs（0.25±0.02）μg/L]、20min[（1.23±0.35）vs（0.30±0.05）μg/L]及30min组[（1.33±0.51）vs（0.28±0.03）μg/L]尿液胱抑素C水平显著升高。结论：尿液胱抑素C测定可望成为缺血/再灌注急性肾损伤的早期诊断标记物。     

Effect of uric acid lowering therapy on the prevention of acute kidney injury in cardiovascular surgery

Purpose

Serum uric acid (SUA) is a novel risk factor for acute kidney injury (AKI), which adversely affects renal blood flow autoregulation, glomerular filtration rate (GFR), and promotes inflammation and angiogenesis. This pilot study investigated the effect of lowering SUA therapy on AKI, by using traditional and non-traditional markers.

Materials and methods

In this prospective, double-blind, placebo-controlled, randomized pilot trial, 26 hyperuricemic patients undergoing cardiac surgery were randomized to receive rasburicase or placebo in the preoperative period.

Results

Subjects receiving rasburicase showed no difference in serum creatinine compared with the control group receiving placebo. Despite no difference in primary endpoint, the rasburicase group had less evidence of renal structural injury as reflected by urine neutrophil-associated lipocalin (uNGAL) concentrations, especially in subjects with higher SUA levels, more severe renal dysfunction (baseline GFR ≤ 45 mL/min/1.73 m²) or heart failure (left ventricular ejection fraction ≤45 %).

Conclusions

In this study, rasburicase showed no benefit on postoperative serum creatinine in hyperuricemic subjects undergoing cardiac surgery. However, the observation that markers of structural renal injury such as uNGAL tended to be lower in rasburicase-treated subjects suggests potential different effects of uricase treatment on hemodynamic alterations in renal function versus structural mechanisms of kidney injury.     

Evaluation of the protective effect of Cystone® against cisplatin-induced nephrotoxicity in cancer patients,and its influence on cisplatin antitumor activity

Purpose

Evaluating the role of cystone, a polyherbal preparation, in protecting cancer patients against cisplatin-induced nephrotoxicity, and its impact on the cytotoxic activity of cisplatin.

Methods

A prospective open-label randomized controlled trial conducted on 49 cancer patients who received six cycles of 70 mg/m² cisplatin-based regimens. The study comprised two groups, a control group (A) in which 28 patients received cisplatin without cystone supplement, and an experimental group (B) in which 21 patients received cisplatin with cystone supplement. Renal function parameters including serum creatinine, creatinine clearance, blood urea, and serum cystatin C were compared between both groups throughout chemotherapy cycles. Patient response to treatment was evaluated in both groups after 3rd and 6th cycles.

Results

At the end of the study, mean levels of serum creatinine, blood urea, and serum cystatin C were significantly lower, whereas creatinine clearance was significantly higher in group (B) compared with group (A). In group (B), there was no significant difference between mean levels of renal markers at baseline and after completion of treatment; while significant changes were observed in group (A). Grading of acute kidney injury according to Common Terminology Criteria for Adverse Events revealed significantly better renal status among patients in group (B) “grades 0 and 1 in 76 and 24 % of the patients, respectively” compared with group (A) “grades 0, 1, and 2 in 36, 32, and 32 % of the patients, respectively”. Based on Response Evaluation Criteria in Solid Tumors, there was no significant difference between both groups.

Conclusions

Cystone can protect cancer patients from cisplatin nephrotoxicity without interfering with its antitumor activity.     

Reference intervals of serum cystatin C/creatinine ratio of 30 postnatal days in neonates

Background

A number of recent reports have suggested that the cystatin C/creatinine (CysC/Cr) ratio might be a useful biomarker of renal function in pediatric patients. In this study we investigated the reference intervals of the serum CysC/Cr ratio for neonates including very low birth weight infants.

Case-Diagnosis/Treatment

A total of 883 blood samples were collected from 246 neonates during the first 30 days of life for the concurrent measurement of serum CysC and Cr levels. Infants with symptoms or signs of acute kidney injury, systemic illness, congenital anomaly, or renal pathology were excluded. The association between serum CysC/Cr ratio and the subgroups of patients was also analyzed. Reference intervals of serum CysC/Cr ratio were determined according to the postnatal age and post-conceptional age (PCA). CysC/Cr ratio level increased according to PCA, except in the first three postnatal days. The serum CysC/Cr ratio correlated positively with gestational age at birth, birth weight, postnatal age, and PCA, and negatively with serum CysC and Cr (P?<?0.001).

Conclusions

Reference levels of serum CysC/Cr ratio were determined according to postnatal age and PCA. As the serum CysC/Cr ratio is dependent on several clinical parameters, these should be considered when assessing the serum CysC/Cr ratio in neonates.     

Is Serum Cystatin C an Accurate Endogenous Marker of Glomerular Filteration Rate for Detection of Early Renal Impairment in Patients with Type 2 Diabetes Mellitus?

Background. Researches have recently reported that serum cystatin C is a more sensitive marker of changes in glomerular filtration rate (GFR) than serum creatinine. We conducted this study to evaluate the significance of serum cystatin C as a more sensitive marker of GFR for early detection of renal impairment in special groups of patients with type 2 diabetes mellitus (DM). Methods. The present study included 40 patients with type 2 DM divided into four equal groups based on their urinary albumin excretion and renal function: group 1 was normoalbuminuric, group 2 was microalbuminuric, group 3 was macroalbuminuric, and group 4 was macroalbuminuric with renal dysfunction. All patients underwent a thorough history, full clinical examination, fasting, and renal function tests. Post-prandial blood glucose levels, glycosylated hemoglobin A1c (HbA1c), proteins, albumin in 24 hr urine, and serum cystatin C were collected. Results. Serum cystatin C and creatinine were significantly higher in macrolbuminuric type 2 diabetic patients with renal dysfunction (group 4: 2.26 ± 1.28, 4.21 ± 2.38 mg/dl, respectively; p < 0.001) than macrolbuminuric type 2 diabetic patients with normal renal function (group 3: 1.04 ± 0.24, 0.96 ± 0.20 mg/dl, respectively), the microalbuminuric group (0.87 ± 0.28, 0.71 ± 0.12 mg/dl, respectively), as well as the normoalbuminuric group (0.55 ± 0.41, 0.60 ± 0.18 mg/dl, respectively). ROC plots demonstrated that area under the curve (AUC) of cystatin C (0.74) was greater than that for creatinine clearance (cr.cl) (0.67) and serum creatinine (s‐cr) (0.74); therefore, the sensitivity and diagnostic accuracy of cystatin c was better than cr. cl., and both were better than s-cr. Serum cystatin C showed significant correlation in groups 2–4 with s-cr, cr.cl, and 24 hr urine albumin, but no correlation was found in group 1. Conclusion. Serum cystatin C is a reliable and easily performed marker for GFR to detect renal impairment in patients with type 2 DM.