Early detection of acute renal failure by serum cystatin C

Biomarkers in Acute Kidney Injury

Biomarkers have become a pillar of precision medicine in acute kidney injury (AKI). Traditional markers for diagnosis of AKI are insensitive and insufficient to provide comprehensive information for prognostication. Several emerging biomarkers have shown promising results in large-scale clinical studies. These novel markers likely will be beneficial for personalized AKI prevention and treatment.

Divergence between serum creatine and cystatin C in estimating glomerular filtration rate of critically ill COVID-19 patients

Background

The clinical use of serum creatine (sCr) and cystatin C (CysC) in kidney function evaluation of critically ill patients has been in continuous discussion. The difference between estimated glomerular filtration rate calculated by sCr (eGFRcr) and CysC (eGFRcysc) of critically ill COVID-19 patients were investigated in this study.

Methods

This is a retrospective, single-center study of critically ill patients with COVID-19 admitted in intensive care unit (ICU) at Wuhan, China. Control cases were moderate COVID-19 patients matched in age and sex at a ratio of 1:1. The eGFRcr and eGFRcysc were compared. The association between eGFR and death were analyzed in critically ill cases. The potential factors influencing the divergence between eGFRcr and eGFRcysc were explored.

Results

A total of 76 critically ill COVID-19 patients were concluded. The mean age was 64.5 ± 9.3 years. The eGFRcr (85.45 (IQR 60.58–99.23) ml/min/1.73m²) were much higher than eGFRcysc (60.6 (IQR 34.75–79.06) ml/min/1.73m²) at ICU admission. About 50 % of them showed eGFRcysc < 60 ml/min/1.73 m² while 25% showed eGFRcr < 60 ml/min/1.73 m² (χ² = 10.133, p = 0.001). This divergence was not observed in moderate group. The potential factors influencing the divergence included serum interleukin-6 (IL-6), tumor necrosis factor (TNF-α) level as well as APACHEII, SOFA scores. Reduced eGFRcr (<60 mL/min/1.73 m²) was associated with death (HR = 1.939, 95%CI 1.078–3.489, p = 0.027).

Conclusions

The eGFRcr was generally higher than eGFRcysc in critically ill COVID-19 cases with severe inflammatory state. The divergence might be affected by inflammatory condition and illness severity. Reduced eGFRcr predicted in-hospital death. In these patients, we advocate for caution when using eGFRcysc.

Acute kidney injury in the critically ill: an updated review on pathophysiology and management

Acute kidney injury (AKI) is now recognized as a heterogeneous syndrome that not only affects acute morbidity and mortality, but also a patient’s long-term prognosis. In this narrative review, an update on various aspects of AKI in critically ill patients will be provided. Focus will be on prediction and early detection of AKI (e.g., the role of biomarkers to identify high-risk patients and the use of machine learning to predict AKI), aspects of pathophysiology and progress in the recognition of different phenotypes of AKI, as well as an update on nephrotoxicity and organ cross-talk. In addition, prevention of AKI (focusing on fluid management, kidney perfusion pressure, and the choice of vasopressor) and supportive treatment of AKI is discussed. Finally, post-AKI risk of long-term sequelae including incident or progression of chronic kidney disease, cardiovascular events and mortality, will be addressed.

Evaluation of acute kidney injury with oxidative stress biomarkers and Renal Resistive Index after cardiac surgery

BACKGROUND

We investigated whether cardiopulmonary bypass (CPB) related oxidative stress mediated glycocalyx degradation can cause an increase in renal resistive index (RRI) or postoperative AKI. Additionally, to evaluate whether RRI and early postoperative serum cystatin C levels could improve the prediction sensitivity of acute kidney injury (AKI).

METHODS

Forty-two patients undergoing cardiac surgery were included in this prospective observational study. RRI was measured pre-operatively and in the cardiac intensive care unit. Blood samples were collected for analyzing of cellular injury biomarkers at preoperative and postoperative second hours. We determined areas under the receiver operating characteristic curve (AUC) and odds ratios for postoperative biomarkers and RRI to predict AKI.

RESULTS

While postoperative cystatin C level (AUC: 0.902, 95% CI = 0.79-1.00, p < .001) and RRI (AUC: 0.748, 95% CI = 0.56-0.93, p = .023) have diagnostic and predictive value in the prediction of AKI, we could not identify any relation between products of oxidative stress and the glycocalyx degradation and AKI.

CONCLUSION

These data suggest that CPB leads to structural and oxidative changes at the protein level and the integrity of glycocalyx is disturbing, but these changes are not specific to kidney injury. Our data suggest that serum cystatin C level and RRI could be used as an early biomarker for postoperative AKI after cardiac surgery.

The Performance of Equations That Estimate Glomerular Filtration Rate against Measured Urinary Creatinine Clearance in Critically Ill Patients

The performance of glomerular filtration rate- (GFR-) estimating equations was studied against creatinine clearance measured by 24-hour urine collection (CrCl_24h-urine) in critically ill patients. Methods. In this substudy of the PermiT trial (https://clinicaltrials.gov/ct2/show/ISRCTN68144998), patients from King Abdulaziz Medical City-Riyadh who had CrCl_24h-urine were included. We estimated GFR using Cockroft–Gault (CG), modification of diet in renal disease study (MDRD), chronic kidney disease epidemiology collaboration (CKD-EPI), and Jelliffe equations. For the CG equation, we entered the actual weight in one calculation (CG_actual-wt), and if BMI ≥30 kg/m², we entered the ideal body weight (CG_ideal-wt) and the adjusted body weight (CG_adjusted-wt) in two calculations. We calculated the MDRD equation based on 4 (MDRD-4) and 6 variables (MDRD-6). The performance of these equations was assessed by different ways including Spearman correlation, bias (difference between estimated GFR and CrCl_24h-urine), precision (standard deviation of bias), and Bland–Altman plot analysis. Results. The cohort consisted of 237 patients (age 45 ± 20 years, males 75%, mechanically ventilated 99% with serum creatinine 101 ± 94 µmol/L and CrCl_24h-urine 108 ± 69 ml/min/1.73 m²). The correlations between the different equations and CrCl_24h-urine were modest (r: 0.62 to 0.79; p < 0.0001). Bias was statistically significant for CG_actual-wt (21 ml/min), CG_adjusted-wt (12 ml/min), and MDRD-6 (-10 ml/min) equations. Precision ranged from 46 to 54 ml/min. The sensitivity of equations to correctly classify CrCl_24h-urine 30–59.9 ml/min/1.73 m² was 17.2% for CG_actual-wt, 30.0% for CG_ideal-wt, 31.0% for CG_adjusted-wt, 31.0% for MDRD-4, 39.1% for MDRD-6, 13.8% for CKD-EPI, and 34.5% for Jelliffe equation. Conclusions. Commonly used GFR-estimating equations had limited ability to properly estimate CrCl_24h-urine and to correctly classify GFR into clinically relevant ranges that usually determine dosing of medications.

Comparison of Different Hydration Strategies in Patients with Very Low-Risk Profiles of Contrast-Induced Nephropathy

BACKGROUND Hydration remains the mainstay of contrast-induced nephropathy (CIN) prevention, and new biomarkers of cystatin C (Cys C) and neutrophil gelatinase-associated lipocalin (NGAL) have been suggested. This study aimed to explore whether hydration is essential in patients with very low-risk profiles of CIN who are undergoing coronary angiography. MATERIAL AND METHODS A total of 150 patients were enrolled and randomly distributed to 3 groups: the Preventive Group (n=50, saline hydration was given 6 h before the procedure until 12 h after the procedure), the Remedial Group (n=50, saline hydration was given after procedure for 12 h), and the No Hydration (NH) group (n=50, saline was only given during the procedure). Serum creatinine (Cr), Cys C, and urinary NGAL were tested 3 times at different times. RESULTS Six patients were excluded because of Mehran risk score >2. There was no CIN among 144 individuals. At 24 h and at 72 h after the procedure, we found no significant differences in the levels of Cr and Cys C (0.72±0.11 mg/L for the Preventive Group, 0.67±0.14 mg/L for the Remedial Group, and 0.70±0.1 6 mg/L for the NH Group) among the 3 groups. Urinary NGAL also did not differ significantly among the 3 groups at 6 h or at 48 h (6.31±6.60 ng/ml for the Preventive Group, 5.00±5.86 ng/ml for the Remedial Group, and 6.97±6.37 ng/ml for the NH Group) after the procedure. Subgroup analysis in patients who underwent percutaneous coronary intervention (PCI) showed that there was no significant difference in serum Cr, Cys C, or urinary NGAL at different time points among the 3 groups. CONCLUSIONS Saline hydration during the perioperative period might be unnecessary in patients with very low-risk profiles of CIN.

Phosphodiesterase (1, 3 & 5) inhibitors attenuate diclofenac-induced acute kidney toxicity in rats

Diclofenac, one of the most commonly used non-steroidal anti-inflammatory drugs, leads to severe adverse effects on the kidneys. The aim of the present study was to investigate the potential pretreatment effect of phosphodiesterase (1, 3 & 5) inhibitors on diclofenac-induced acute renal failure in rats. Rats orally received pentoxifylline (100 mg/kg), vinpocetine (20 mg/kg), cilostazol (50 mg/kg), or sildenafil (5 mg/kg) once per day for 6 consecutive days. Diclofenac (15 mg/kg) was injected on day-4, -5 and -6 in all groups except normal control group. The used phosphodiesterase inhibitors significantly reduced the diclofenac-induced elevation in the serum levels of blood urea nitrogen, creatinine and cystatin C. Moreover, the renal tissue contents of tumor necrosis factor (TNF)-α, nuclear factor (NF)-κB as well as the protein expression of toll-like receptor (TLR) 4 and high mobility group box (HMGB) 1 were markedly reduced by the used phosphodiesterase inhibitors, as compared to the diclofenac control. This was reflected on the marked improvement in histopathological changes induced by diclofenac. Sildenafil showed the best protection regarding TNF-α and NF-κB, while cilostazol showed the best results regarding TLR4, HMGB1 and histopathological examination. This study revealed the good protective effect of these phosphodiesterase inhibitors against diclofenac-induced acute renal failure.

Is microvascular dysfunction a systemic disorder with common biomarkers found in the heart, brain, and kidneys? - A scoping review

Although microvascular dysfunction (MVD) has been well characterized in individual organs as different disease entities, clinical evidence is mounting in support of an underlying systemic process. To address this hypothesis, we systematically searched PubMed and Medline for studies in adults published between 2014 and 2019 that measured blood biomarkers of MVD in three vital organs i.e. brain, heart, and the kidney. Of the 9706 unique articles 321 met the criteria, reporting 49 biomarkers of which 16 were common to the three organs. Endothelial dysfunction, inflammation including reactive oxidation, immune activation, and coagulation were the commonly recognized pathways. Triglyceride, C-reactive protein, Cystatin C, homocysteine, uric acid, IL-6, NT-proBNP, thrombomodulin, von Willebrand Factor, and uric acid were increased in MVD of all three organs. In contrast, vitamin D was decreased. Adiponectin, asymmetric dimethylarginine, total cholesterol, high-density and low-density cholesterol were found to be variably increased or decreased in studies. We review the pathways underlying MVD in the three organs and summarize evidence supporting its systemic nature. This scoping review informs clinicians and researchers in the multi-system manifestation of MVD. Future work should focus on longitudinal investigations to evaluate the multi-system involvement of this disease.

Effects of pneumoperitoneum on kidney injury biomarkers: A randomized clinical trial

Background

Increased intra-abdominal pressure causes hemodynamic changes that may affect renal biomarkers.

Methods

This randomized, single-blind, single-center clinical trial recruited patients undergoing laparoscopic cholecystectomy at a tertiary care center in Brazil. They were randomly allocated to a standard intra-abdominal pressure group (P_10-12, 10–12 mm Hg) and a low intra-abdominal pressure group (P_6-8, 6–8 mm Hg). The primary outcome was the change in neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C levels measured at the beginning of the procedure (T0), at the end of the procedure (T1), and 24 hours after the procedure (T2). P-values < 0.05 were considered statistically significant.

Results

In total, 64 patients completed the study—33 were given standard pressure and 31 were given low pressure. There was no significant difference in the biomarker between the groups (P = 0.580), but there was a significant difference between the time points with elevation at T1 (P < 0.001). Similar to NGAL, cystatin C had an elevation at T1 in both groups (P = 0.021), but no difference was found when comparing the groups.

Conclusions

In laparoscopic cholecystectomy, pneumoperitoneum increases NGAL and cystatin C levels intraoperatively, and the use of low-pressure pneumoperitoneum does not change the course of these biomarkers.

Association between severe chronic kidney disease defined by cystatin-c and creatinine and clinical outcomes in an elderly population - an observational study

Introduction:

Estimated glomerular filtration rate (eGFR) based on serum cystatin-C (sCys) seems as accurate as when based on serum creatinine (sCr), but sCys seems a better predictor of adverse outcomes. We aimed to study whether sCys could be a reliable tool for the prediction of adverse outcomes in elderly patients with severe chronic kidney disease (CKD).

Methods:

A group of 348 elderly patients with non-end-stage CKD (stages 1-4, according to eGFR-EPI sCr and/or sCys), referred to our consultation unit during 2016, was retrospectively studied and divided into four exclusive categories: CKD_stage4_neither (eGFR-sCr≥30mL/min; eGFR-sCys≥30mL/min), CKD_stage4_sCr_only (eGFR-sCr<30mL/min), CKD_stage4_sCys_only (eGFR-sCys<30mL/min) and CKD_stage4_combined (eGFRsCr<30mL/min; eGFR-sCys<30mL/min). Baseline characteristics, predictors of death, and clinical events (cardiovascular events and admissions for cardiovascular, acute kidney injury or infectious events) were explored until December 2018.

Results:

A 77±7.4 year-old cohort, with a modified Charlson Comorbidty Index (mCCI) of 3 (IQR:1-4), was followed-up during 29 (IQR: 26-33) months. There were no significant differences between the characteristics of the stage 4 groups. Survival analysis was stratified by follow-up at 12 months, and in the first year, survival curves of CKD_stage4_sCys_only and CKD_stage4_combined groups were significantly lower than the other groups (p=0.028). Adjusting for age, sex, and mCCI, CKD_stage4_sCys_only, conversely to CKD_stage4_sCr_only, had higher rates of clinical events (p<0.05) than CKD_stage4_neither group.

Conclusion:

In elderly patients with discordant CKD staging, sCys-based eGFR seems to be a better predictor of adverse outcomes than sCr-based eGFR. Patients with stage 4 CKD defined by sCr alone seem to behave similar to those with less severe CKD.

The effect of glucocorticoids on serum cystatin C in identifying acute kidney injury: a propensity-matched cohort study

BACKGROUND

Glucocorticoids may impact the accuracy of serum cystatin C (sCysC) in reflecting renal function. We aimed to assess the effect of glucocorticoids on the performance of sCysC in detecting acute kidney injury (AKI) in critically ill patients.

METHODS

A prospective observational cohort study was performed in a general intensive care unit (ICU). Using propensity score matching, we successfully matched 240 glucocorticoid users with 960 non-users among 2716 patients. Serum creatinine (SCr) and sCysC were measured for all patients at ICU admission. Patients were divided into four groups based on cumulative doses of glucocorticoids within 5 days before ICU admission (Group I: non-users; Group II: 0 mg < prednisone ≤50 mg; Group III: 50 mg < prednisone ≤150 mg; Group IV: prednisone > 150 mg). We compared the performance of sCysC for diagnosing and predicting AKI in different groups using the area under the receiver operator characteristic curve (AUC).

RESULTS

A total of 240 patients received glucocorticoid medication within 5 days before ICU admission. Before and after matching, the differences of sCysC levels between glucocorticoid users and non-users were both significant (P <  0.001). The multiple linear regression analysis revealed that glucocorticoids were independently associated with sCysC (P <  0.001). After matching, the group I had significantly lower sCysC levels than the group III and group IV (P <  0.05), but there were no significant differences in sCysC levels within different glucocorticoids recipient groups (P > 0.05). Simultaneously, we did not find significant differences in the AUC between any two groups in the matched cohort (P > 0.05).

CONCLUSIONS

Glucocorticoids did not impact the performance of sCysC in identifying AKI in critically ill patients.

Risk factors and long-term outcomes of elderly patients complicating with acute kidney injury after type A acute aortic dissection surgery: a retrospective study

Background

To identify risk factors and long-term outcomes for acute kidney injury (AKI) in elderly patients who underwent type A acute aortic dissection (TA-AAD) emergency surgeries.

Methods

This retrospective study enrolled 214 consecutive patients who underwent TA-AAD emergency surgeries between January 2014 to December 2018 in Nanjing Drum Tower hospital. The diagnosis of AKI was made based on the Kidney Disease: Improving Global Outcomes definition (KDIGO) criteria. Multivariable regression analysis was performed to identify risk factors for postoperative AKI. Kaplan-Meier curves were generated to compare the long-term outcomes between patients with and without AKI complication after TA-AAD surgeries.

Results

Among all enrolled patients, 114 (53.3%) developed AKI during postoperative period. The median age of patients with or without AKI was 68.0 (64.0, 74.0) and 66.0 (62.0, 72.8) years respectively. Renal replacement therapy (RRT) was required in 43 patients (20.1%). The 30-day mortality rate was 21.5% in all enrolled patients with 26.3% in AKI group and 16.0% in non-AKI group (P=0.067) respectively. Longer mechanical ventilation duration was identified as the only independent risk factor for developing AKI by multivariable logistic regression analysis. In addition, our data suggested that the long-term cumulative survival rate was different between two groups.

Conclusions

Postoperative AKI after TA-AAD surgeries was common and associated with worsened long-term mortality in elderly patients. Longer postoperative mechanical ventilation duration was identified as the only independent risk factor for the development of AKI.

Quercetin and lithium chloride potentiate the protective effects of carvedilol against renal ischemia-reperfusion injury in high-fructose, high-fat diet-fed Swiss albino mice independent of renal lipid signaling

Renal ischemia-reperfusion injury (R-IRI) is the main cause of acute renal failure. Carvedilol has been shown to protect against R-IRI. However, the underlying mechanisms are still not completely clarified. This study aimed to investigate the role of lipid signaling in mediating carvedilol protective effects against R-IRI in insulin-resistant mice by using two different lipid signaling modulators, quercetin and lithium chloride (LiCl). Mice were fed high-fructose, high-fat diet (HFrHFD) for 16 weeks to induce insulin resistance. At the end of feeding period, mice were randomly distributed into five groups; Sham, R-IRI, Carvedilol (20 mg/kg, i.p.), Carvedilol + Quercetin (10 mg/kg, i.p.), Carvedilol + LiCl (200 mg/kg, i.p.). R-IRI was performed by applying 30 min of unilateral renal ischemia followed by one hour of reperfusion. Quercetin and LiCl were administered 30 min before carvedilol administration and carvedilol was administered 30 min before ischemia. Changes in kidney function tests, histopathology, fibrosis area, lipid signaling, inflammatory, apoptosis and oxidative stress markers in the kidney were measured. Results showed that R-IRI decreased kidney function, impaired renal tissue integrity, modulated lipid signaling and increased renal inflammation, apoptosis and oxidative stress. Carvedilol treatment decreased the detrimental effects induced by R-IRI. In addition, pre-injection of both quercetin and LiCl potentiated the reno-protective effects of carvedilol against R-IRI independent of changes in lipid mediators like phosphatidyl inositol 4,5 bisphosphate (PIP2) and diacylglycerol (DAG). In conclusion, quercetin and LiCl potentiate the protective effects of carvedilol against R-IRI in HFrHFD-fed mice by reducing inflammation and oxidative stress independent of lipid signaling.

Risk factors and long-term outcomes of acute kidney injury complication after type A acute aortic dissection surgery in young patients

OBJECTIVE

To identify risk factors and long-term outcomes of acute kidney injury (AKI) in young patients who underwent type A acute aortic dissection (TA-AAD) emergency surgeries.

METHODS

This retrospective study enrolled 121 consecutive patients less than 40 years old who received TA-AAD emergency surgeries between January 2014 to December 2018 in Nanjing Drum Tower hospital. The diagnosis of AKI was made based on the KDIGO criteria. Multivariable regression analysis was performed to identify risk factors for postoperative AKI. Kaplan-Meier curves were generated to compare long-term outcomes between patients with and without AKI complication after TA-AAD surgeries.

RESULTS

Among all enrolled patients, AKI occurred in 51 patients (42.1%) and renal replacement therapy (RRT) was required in 15 patients (12.4%). The development of postoperative AKI was associated with increased 30-day mortality (P = 0.041), longer ICU stay time (P < 0.001) and hospital stay time (P = 0.006). Multivariable analysis indicated that elevated preoperative serum cystatin C (sCyC) (OR = 6.506, 95% CI: 1.852-22.855, P = 0.003) was the only independent risk factor for developing AKI. The areas under the receiver-operating characteristic curve (AUC) of preoperative sCyC was 0.800 (95% CI: 0.719, 0.882). Preoperative sCyC had a sensitivity of 64.7% and a specificity of 83.8% in diagnosing postoperative AKI with a cut-off value of 0.895 mg/L. In addition, our data suggested there was no difference discovered regarding long-term cumulative survival rate between patients with and without AKI during a median 29 months follow-up period.

CONCLUSIONS

Postoperative AKI after TA-AAD surgeries was relatively common in young patients and associated with increased short-term mortality. Elevated preoperative sCyC was identified as an independent risk factor for AKI with potential diagnostic merit.

Are endourological procedures for nephrolithiasis treatment associated with renal injury? A review of potential mechanisms and novel diagnostic indexes

Nephrolithiasis is one of the most common urological conditions with a huge socio-economic impact. About 50% of recurrent stone-formers have just one lifetime recurrence and >10% of patients present with a high recurrent disease requiring subsequent and sometimes multiple surgical interventions. The advent of new technology has made endourological procedures the pinnacle of stone treatment, including procedures like percutaneous nephrolithotomy (PCNL), retrograde intrarenal surgery and miniaturized PCNL procedures. Researchers have primarily focused on comparisons with respect to stone-free rates, procedure parameters and post-operative complications. However, the effect of these three procedures on renal function or indexes of renal injury has not been sufficiently examined. This was only reported in a few studies as a secondary objective with the use of common and not the appropriate and detailed renal parameters. This review presents current literature regarding the use of novel and highly predictive biomarkers for diagnosing acute kidney injury, discusses potential mechanisms through which endourological procedures for renal stone treatment may affect renal function and proposes areas with open questions where future research efforts in the field should focus.

Protective Effects and Mechanisms of Rosuvastatin on Acute Kidney Injury Induced by Contrast Media in Rats

Objective

To explore the protective effect and mechanism of rosuvastatin on acute renal injury induced by a nonionic hypotonic contrast medium in rats.

Methods

Forty-eight healthy adult SD rats were randomly divided into three groups: normal control group (NC); contrast medium control group (CM); and rosuvastatin intervention group (RI). The RI group was intragastrically administered with a 10 mg/kg of rosuvastatin 12 h prior to the contrast exposure. All rats in CM and RI groups were inoculated with 10 mL/kg of chemical (IV) while the same volume of saline for the NC group. At 24 h and 72 h posttreatments, pathomorphological changes of renal tubules were documented, respectively, and several biochemical indicators were tested to assess renal injury of experimental rats.

Results

Compared with the CM group, rats in the RI group showed significantly reduced injury of kidneys and decreased levels of biochemical indicators such as blood Scr, blood Cys-C, urine NAG, urine α1-MG, and urine mALB. The serum Hs-CRP in the CM group increased significantly from 24 h to 72 h (p < 0.05), but this was not observed in the rats of the RI group. In addition, SOD activity in the RI group was significantly increased (p < 0.01) while SOD activity in renal tissue decreased significantly with time in the CM group (p < 0.05).

Conclusion

Short-term intervention with rosuvastatin can lead to reduced kidney damage associated with the contrast agent by reducing the levels of inflammatory factors and oxidative stress. Thus, rosuvastatin intervention has a protective effect on rats from contrast-induced nephropathy.

Urinary kidney injury molecule-1: a novel biomarker to monitor renal function in patients with unilateral ureteral obstruction

PURPOSE

This study aimed to investigate the clinical significance of urinary kidney injury molecule-1 (KIM-1) to monitor renal function in patients with obstructive unilateral ureteral calculi.

METHODS

Kidneys of 12 male C57BL/6J mice, as well as their urine and plasma specimens, were extracted to detect KIM-1 expressions 24 h after unilateral ureteral obstruction (UUO) construction or sham surgery. Meanwhile, a cohort of 89 patients with unilateral ureteral calculi was retrospectively reviewed. 46 of which received double-J ureteral stent indwelling (group 1) and the remaining 43 were treated conservatively (group 2). Urinary KIM-1 levels in the baseline, 2 h and 1 day after treatments were analyzed.

RESULTS

KIM-1 expressions were dramatically higher in mice underwent UUO surgery when compared with the sham group. Clinical data showed urinary KIM-1 levels decreased as time went by for patients in group 1 (1.787 ± 1.081 ng/mL for baseline, 1.668 ± 1.162 ng/mL for 2 h and 0.935 ± 0.526 ng/mL for 1 day after operation; p = 0.0001). Nevertheless, for those in group 2, a mild increase (1.659 ± 0.997 ng/mL, 1.691 ± 0.872 ng/mL and 1.675 ± 0.911 ng/mL, correspondingly; p = 0.9869) was observed. Additionally, a urinary KIM-1 value of 1.04 ng/mL had a sensitivity of 83.1% and specificity of 62.5% to predict the presence of hydronephrosis (95% CI: 0.641-0.873, AUC: 0.757, p < 0.001).

CONCLUSIONS

Urinary KIM-1 is a sensitive biomarker of post-renal acute kidney injury (AKI) and might predict the presence of hydronephrosis. It can be used as an effective surrogate to monitor renal function.

Dual assessment of kidney perfusion and pH by exploiting a dynamic CEST-MRI approach in an acute kidney ischemia-reperfusion injury murine model

Several factors can lead to acute kidney injury, but damage following ischemia and reperfusion injuries is the main risk factor and usually develops into chronic disease. MRI has often been proposed as a method with which to assess renal function. It does so by measuring the renal perfusion of an injected Gd-based contrast agent. The use of pH-responsive agents as part of the CEST (chemical exchange saturation transfer)-MRI technique has recently shown that pH homeostasis is also an important indicator of kidney functionality. However, there is still a need for methods that can provide more than one type of information following the injection of a single contrast agent for the characterization of renal function. Herein we propose, for the first time, dynamic CEST acquisition following iopamidol injection to quantify renal function by assessing both perfusion and pH homeostasis. The aim of this study is to assess renal functionality in a murine unilateral ischemia-reperfusion injury model at two time points (3 and 7 days) after acute kidney injury. The renal-perfusion estimates measured with iopamidol were compared with those obtained with a gadolinium-based agent, via a dynamic contrast enhanced (DCE)-MRI approach, to validate the proposed method. Compared with the contralateral kidneys, the clamped ones showed a significant decrease in renal perfusion, as measured using the DCE-MRI approach, which is consistent with reduced filtration capability. Dynamic CEST-MRI findings provided similar results, indicating that the clamped kidneys displayed significantly reduced renal filtration that persisted up to 7 days after the damage. In addition, CEST-MRI pH imaging showed that the clamped kidneys displayed significantly increased pH values, reflecting the disturbance to pH homeostasis. Our results demonstrate that a single CEST-MRI contrast agent can provide multiple types of information related to renal function and can discern healthy kidneys from pathological ones by combining perfusion measurements with renal pH mapping.

Biomarkers of Contrast-Induced Nephropathy:: Which Ones are Clinically Important?

Contrast-induced acute kidney injury (CI-AKI) is a common complication after intravascular injection of iodinated contrast media, and it is associated with a prolonged in-hospital stay and unfavorable outcome. CI-AKI occurs in 5% to 20% among hospitalized patients. Its diagnosis relies on the increase in serum creatinine levels, which is a late biomarker of kidney injury. Novel and early serum and urinary biomarkers have been identified to detect kidney damage before the expected serum creatinine increase.

Mechanism of Chronic Kidney Disease Progression and Novel Biomarkers: A Metabolomic Analysis of Experimental Glomerulonephritis

While a complex network of cellular and molecular events is known to be involved in the pathophysiological mechanism of chronic kidney disease (CKD), the divergence point between reversal and progression and the event that triggers CKD progression are still unknown. To understand the different mechanisms between reversible and irreversible kidney disease and to search for urinary biomarkers that can predict prognosis, a metabolomic analysis was applied to compare acute and chronic experimental glomerulonephritis (GN) models. Four metabolites, namely, epoxyoctadecenoic acid (EpOME), epoxyeicosatetraenoic acid (EpETE), α-linolenic acid (ALA), and hydroxyretinoic acid, were identified as predictive markers after comparing the chronic nephritis model with acute nephritis and control groups (false discovery rate adjusted p-value (q-value) < 0.05). Renal mRNA expression of cytochrome P450 and epoxide hydrolase was also identified as being involved in the production of epoxide metabolites from these polyunsaturated fatty acids (p < 0.05). These results suggested that the progression of chronic kidney disease is associated with abnormally activated epoxide hydrolase, leading to an increase in EpOME and EpETE as pro-inflammatory eicosanoids.

Perioperative acute kidney injury: Stratification and risk reduction strategies

Perioperative acute kidney injury (AKI) is associated with increased morbidity and mortality. Patient comorbidities, the type of surgery, timing of surgery, and exposure to nephrotoxins are important contributors for developing acute kidney injury. Urgent or emergent surgery, cardiac, and organ transplantation procedures are associated with a higher risk of acute kidney injury. Nephrotoxic drugs, contrast dye, and diuretics can worsen preexisting kidney dysfunction or act as an additive and/or synergistic insult to perioperative injury. A history of preoperative chronic kidney disease is the main risk factor for developing AKI, conferring as much as a 10-fold risk. However, beyond the preoperative renal function, the development of AKI is a complex phenomenon that involves a combination of patient-related and surgery-related factors.

Predictive value of cystatin C and neutrophil gelatinase-associated lipocalin in contrast-induced nephropathy: A meta-analysis

Background

There are still limited studies comprehensively examining the diagnostic performance of neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C in contrast-induced nephropathy (CIN). The study aimed to investigate and compare the predictive value of NGAL and cystatin C in the early diagnosis of CIN.

Methods and materials

We searched the PubMed, EMBASE and Cochrane Library databases until November 10, 2019. The methodological quality of the included studies was assessed by the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Bivariate modeling and hierarchical summary receiver operating characteristic (HSROC) modeling were performed to summarize and compare the diagnostic performance of blood/urine NGAL and serum cystatin C in CIN. Subgroup and meta-regression analyses were performed according to the study and patient characteristics.

Results

Thirty-seven studies from thirty-one original studies were included (blood NGAL, 1840 patients in 9 studies; urine NGAL, 1701 patients in 10 studies; serum cystatin C, 5509 patients in 18 studies). Overall, serum cystatin C performed better than serum/urine NGAL (pooled DOR: 43 (95%CI: 12–152); AUROC: 0.93; λ: 3.79); serum and urine NGAL had a similar diagnostic performance (pooled DOR: 25 (95%CI: 6–108)/22(95%CI: 8–64); AUROC: 0.90/0.89; λ: 3.20/3.08). Meta-regression analysis indicated that the sources of heterogeneity might be CIN definition, assays, and nationalities.

Conclusion

Both NGAL and cystatin C can serve as early diagnostic indicators of CIN, while cystatin C may perform better than NGAL.

Plasma cystatin C versus renal resistive index as early predictors of acute kidney injury in critically ill neonates

INTRODUCTION

Acute kidney injury (AKI) independently predicts morbidity and mortality of critically ill neonates. Serum cystatin C is a promising early biomarker for AKI. Evaluating the renal resistive index (RRI) by Doppler ultrasound demonstrates abnormal intrarenal vascular impendence.

OBJECTIVE

The objective of this study was to compare the ability of plasma cystatin C and the RRI to predict AKI early in critically ill neonates.

STUDY DESIGN

Sixty critically ill neonates in neonatal intensive care units were assigned to three groups: group 1 (cases) of thirty participants fulfilling the AKI diagnostic criteria of neonatal Kidney Disease Improving Global Outcome, group 2 of thirty participants not fulfilling the criteria, as well as the 3rd group of thirty age- and sex-matching healthy participants.

RESULTS

Group 1 demonstrated a significantly high mean cystatin C level during the 1st day of incubation compared with the other two groups [group 1 (3.18 ± 1.25), group 2 (1.68 ± 0.66), and group 3 (0.80 ± 0.26)]. Serum creatinine and RRI were insignificantly different among all groups. At a cutoff value of 2.68 (mg/l), cystatin C level had significantly higher area under the curve (AUC) (0.804) than both serum creatinine (0.453) and RRI (0.551) and had 53.3% sensitivity and 100% specificity in the early prediction of neonates with AKI. The RRI had a lower non-significant AUC (0.551) at a cutoff value of 0.53 and had 100% sensitivity and 40% specificity, while serum creatinine had a low non-significant AUC (0.453) at a cutoff value of 0.49 (mg/dl) and had 33.3% sensitivity and 86.7% specificity. Applying regression analysis to predict AKI in critically ill neonates as early as possible, higher plasma cystatin C and lower estimated glomerular filtration rate cystatin were the only independent risk factors within critically ill neonates.

CONCLUSIONS

The level of plasma cystatin C increased 48 h before both RRI and serum creatinine did in critically ill neonates who developed AKI, so it is more reliable in predicting AKI in critically ill neonates than serum creatinine and RRI.

The effects of shock wave lithotripsy and retrograde intrarenal surgery on renal function

Introduction: The aim of this study was to compare the early effects of shock wave lithotripsy (SWL) and retrograde intrarenal surgery (RIRS) on renal function using the cystatin C levels.Material and methods: Serum samples were taken from each of the patients preoperatively, on the first postoperative day, and on the 30th postoperative day in order to evaluate the renal damage. The cystatin C level was determined using a particle-enhanced turbid metric immunoassay with a clinical chemistry analyzer.Results: In the comparison between the preoperative and postoperative cystatin C levels on day 1, there was an increase in the SWL group (p = .001); however, the decrease in the RIRS group was statistically significant (p = .007). There were statistically significant differences in the cystatin C levels on the first postoperative day in both groups (p = .001). In the SWL group, there was a statistically significant increase between the preoperative and the 30th postoperative day cystatin C levels (p = .006), but no differences were found between these levels in the RIRS group or between the two groups (p = .255).Conclusions: RIRS may be the preferred procedure for patients who need more renal function protection when treating renal stones <2 cm.

Effects of flexible ureteroscopy on kidney: A prospective clinical trial

OBJECTIVE

To investigate the effects of flexible ureteroscopy (F-URS) on the operated side of a kidney by assessing the renal damage markers, urine neutrophil gelatinase-related lipocalin (NGAL) and serum cystatin-C (Cys-C), and overall kidney function with the measurements of standard serum creatinine and urine albumin and protein levels.

MATERIAL AND METHODS

A total of 30 patients who underwent F-URS for treatment of upper urinary stone disease were prospectively evaluated. Preoperative serum urea, creatinine, and Cys-C levels were noted. Levels of urine albumin, protein, creatinine, and NGAL in spot urine samples from the operated side of a kidney obtained through the access sheath preoperatively and through the ureteral catheter 1 and 24 hours postoperatively were also measured. Preoperative and postoperative parameter levels were statistically compared.

RESULTS

The patients' mean age was 46.6±15.9 years. The mean operative and fluoroscopy times were 90.67±32.5 and 3.15±1.43 minutes, respectively. The urine creatinine, albumin, protein, albumin/creatinine, and protein/creatinine levels were similar in preoperative and postoperative periods. Postoperative serum urea, creatinine, and Cys-C levels and urine NGAL and NGAL/creatinine levels were not also found with remarkable changes from the baseline levels.

CONCLUSION

F-URS is a safe therapeutic intervention in the treatment of urolithiasis, especially regarding renal damage, and functional outcomes.

Determination of Cystatin C in human urine by isotope dilution tandem mass spectrometry

This work presents the development of a methodology for the accurate and precise quantification of the renal biomarker Cystatin C in human urine by Isotope Dilution Mass Spectrometry (IDMS). The procedure is based on the addition of a known quantity of the proteotypic peptide ALDFAVG*EYNK labelled with ¹³C₂-glycine to the urine sample followed by protein hydrolysis using trypsin. Then, preconcentration and purification of the isotope diluted peptide was carried out by a selective monoclonal antibody bound to magnetic beads and final measurement was done after injection of the sample in a HPLC-MS/MS triple quadrupole instrument. The isotopic distribution of the isotope diluted proteotypic peptide was measured by low resolution selected reaction monitoring. Using this aquisition mode, the bandpass of the first quadrupole was widened (FWHM =13 u) so the whole isotopic clusters for both the natural abundance and the labelled peptides entered the collision cell. The proposed acquisition mode provided similar accuracy and precision than the regular SRM mode (FWHM =0.7 u) but a higher sensitivity was observed. The purification of the sample by antibody based enrichment of the target peptide was shown to remove interfering compounds more efficiently in comparison with a sample purification based on semipreparative liquid chromatography. Using 5 ng of the labelled peptide it was possible to quantify Cystatin C in human urine in patients with normal and impaired renal function. Recoveries from 100 to 104% were obtained in samples containing from 90 to 700 μg L^-1 of Cystatin C with relative standard deviations from 0.5 to 6%. The stability of Cystatin C in urine samples was evaluated under different storage conditions showing that only when the urine samples were stored at room temperature during more than 10 days, a significant degradation of Cystatin C was observed.

Fluid Overload in Special Pediatric Cohorts With Anomalous Origin of the Left Coronary Artery From the Pulmonary Artery Following Surgical Repair

OBJECTIVE

To investigate the prevalence, risk factors, and clinical outcomes associated with early fluid overload (FO) in a special group of pediatric patients undergoing repair of anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA).

DESIGN

It was a retrospective study performed with multiple variable regression analysis.

SETTING

A single cardiac surgical institution.

PARTICIPANTS

Eighty-eight patients younger than 18 years of age undergoing ALCAPA surgical repair with cardiopulmonary bypass were recruited at the authors' institution from June 2010 to September 2017.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Of 88 pediatric patients with ALCAPA after surgical repair, 37.5% developed early FO, defined as fluid accumulation ≥5% within the period from surgery until midnight of postoperative day 1. Patients with early FO were younger, weighed less, and had worse preoperative cardiac dysfunction. With logistic regression analysis, being underweight was confirmed to be a risk factor for FO development (odds ratio, 8.66; 95% confidence interval, 2.83-26.52; p < 0.001). Early FO also predicted severe acute kidney injury, respiratory morbidity, and low cardiac output syndrome after reimplantation procedure. Patients with early FO also had significantly longer mechanical ventilation hours (p  <  0.001), intensive care unit length of stay (p = 0.003), and hospital length of stay (p = 0.009).

CONCLUSION

Early FO ≥5% has been linked to adverse postoperative outcomes in pediatric patients undergoing repair for ALCAPA. The use of restrictive fluid management is crucial for patients who have lower weight and poor myocardial function before and after complex surgical procedures such as in ALCAPA settings.

Biomarkers in Stress Related Diseases/Disorders: Diagnostic, Prognostic, and Therapeutic Values

Various internal and external factors negatively affect the homeostatic equilibrium of organisms at the molecular to the whole-body level, inducing the so-called state of stress. Stress affects an organism's welfare status and induces energy-consuming mechanisms to combat the subsequent ill effects; thus, the individual may be immunocompromised, making them vulnerable to pathogens. The information presented here has been extensively reviewed, compiled, and analyzed from authenticated published resources available on Medline, PubMed, PubMed Central, Science Direct, and other scientific databases. Stress levels can be monitored by the quantitative and qualitative measurement of biomarkers. Potential markers of stress include thermal stress markers, such as heat shock proteins (HSPs), innate immune markers, such as Acute Phase Proteins (APPs), oxidative stress markers, and chemical secretions in the saliva and urine. In addition, stress biomarkers also play critical roles in the prognosis of stress-related diseases and disorders, and therapy guidance. Moreover, different components have been identified as potent mediators of cardiovascular, central nervous system, hepatic, and nephrological disorders, which can also be employed to evaluate these conditions precisely, but with stringent validation and specificity. Considerable scientific advances have been made in the detection, quantitation, and application of these biomarkers. The present review describes the current progress of identifying biomarkers, their prognostic, and therapeutic values.

Biomarkers in Stress Related Diseases/Disorders: Diagnostic, Prognostic, and Therapeutic Values

Various internal and external factors negatively affect the homeostatic equilibrium of organisms at the molecular to the whole-body level, inducing the so-called state of stress. Stress affects an organism's welfare status and induces energy-consuming mechanisms to combat the subsequent ill effects; thus, the individual may be immunocompromised, making them vulnerable to pathogens. The information presented here has been extensively reviewed, compiled, and analyzed from authenticated published resources available on Medline, PubMed, PubMed Central, Science Direct, and other scientific databases. Stress levels can be monitored by the quantitative and qualitative measurement of biomarkers. Potential markers of stress include thermal stress markers, such as heat shock proteins (HSPs), innate immune markers, such as Acute Phase Proteins (APPs), oxidative stress markers, and chemical secretions in the saliva and urine. In addition, stress biomarkers also play critical roles in the prognosis of stress-related diseases and disorders, and therapy guidance. Moreover, different components have been identified as potent mediators of cardiovascular, central nervous system, hepatic, and nephrological disorders, which can also be employed to evaluate these conditions precisely, but with stringent validation and specificity. Considerable scientific advances have been made in the detection, quantitation, and application of these biomarkers. The present review describes the current progress of identifying biomarkers, their prognostic, and therapeutic values.

Clinical prospects of biomarkers for the early detection and/or prediction of organ injury associated with pharmacotherapy

Several biomarkers are used to monitor organ damage caused by drug toxicity. Traditional markers of kidney function, such as serum creatinine and blood urea nitrogen are commonly used to estimate glomerular filtration rate. However, these markers have several limitations including poor specificity and sensitivity. A number of serum and urine biomarkers have recently been described to detect kidney damage caused by drugs such as cisplatin, gentamicin, vancomycin, and tacrolimus. Neutrophil gelatinase-associated lipocalin (NGAL), liver-type fatty acid-binding protein (L-FABP), kidney injury molecule-1 (KIM-1), monocyte chemotactic protein-1 (MCP-1), and cystatin C have been identified as biomarkers for early kidney damage. Hy's Law is widely used as to predict a high risk of severe drug-induced liver injury caused by drugs such as acetaminophen. Recent reports have indicated that glutamate dehydrogenase (GLDH), high-mobility group box 1 (HMGB-1), Keratin-18 (k18), MicroRNA-122 and ornithine carbamoyltransferase (OCT) are more sensitive markers of hepatotoxicity compared to the traditional markers including the blood levels of amiotransferases and total bilirubin. Additionally, the rapid development of proteomic technologies in biofluids and tissue provides a new multi-marker panel, leading to the discovery of more sensitive biomarkers. In this review, an update topics of biomarkers for the detection of kidney or liver injury associated with pharmacotherapy.

Remote Ischemic Preconditioning in Renal Protection During Elective Percutaneous Coronary Intervention

Remote ischemic preconditioning (RIPC) exerts protection in remote organs. The purpose of this study was to investigate the potential of RIPC to prevent contrast induced nephropathy. One hundred and twenty four patients were randomized to elective percutaneous coronary intervention with or without RIPC. RIPC was performed using three cycles of 5-min inflation to 200 mmHg of a standard upper arm blood pressure cuff. The time between the last inflation cycle and the coronary intervention was less than 2 h. The primary endpoint was the incidence of contrast-induced nephropathy based on the standard criteria of the serum creatinine (SC) and cystatin C (CC) levels. The rates of major cardiac and cerebral adverse events (MACCE) during 1 year follow-up were evaluated. We found that contrast-induced nephropathy assessed by SC occurred in 4.9% (3/61) patients with RIPC and in 12.1% (7/58) patients without it (p = 0.20). Nephropathy assessed by CC occurred in 1.7% (1/58) patients with RIPC and 3.5% (2/57) patients without it (p = 0.62). There was no coincidence between the diagnosis of contrast-induced nephropathy based on SC and CC (McNemar test 0.012, κ = 0.28); SC was a more sensitive marker of nephropathy than CC (ten and three cases, respectively). The MACCE rate during the year of follow-up tended to be lower with the ischemic preconditioning than without it, four vs. six cases, respectively. We conclude that RIPC prior to percutaneous coronary intervention has no major influence on the development of contrast-induced nephropathy and does not improve the one-year outcome.

Is it possible to prevent contrast-induced nephropathy with dexpanthenol?

PURPOSE

Contrast-induced nephropathy (CIN) is one of the side effects of diagnostic procedures. Oxidative stress plays an important role in CIN's pathophysiology. Dexpanthenol (Dexp) is a substance with antioxidant efficacy. We investigated the likely protective effects of dexpanthenol for CIN.

METHODS

Twenty-four Sprague-Dawley rats were divided randomly into four groups of 6 rats; control (group 1), Dexp (group 2), CIN (group 3) and Dexp + CIN (group 4). All rats were restricted of water moderately to facilitate of nephrotoxicity. Dexp was administered into the intraperitoneally at a dose of 500 mg/kg for 5 days in groups 2 and 4. The same amount of saline was applied via intraperitoneally to group 1 and 3. In CIN and Dexp + CIN groups, L-NAME (10 mg/kg), tenoxicam (0.5 mg/kg) and sodium amidotrizoate (10 ml/kg) were administered on the 4th day via the tail vein for CIN. All rats were euthanized on the 6th day and samples for biochemical and pathological evaluations were collected.

RESULTS

When the Dexp + CIN group and the CIN group were compared, it was found to be provide a significant decline at the level of acute tubular injury and necrosis in kidney biopsies by dexp. Furthermore Dexp significantly reduced the serum cystatin C (Cys-C) levels, not serum creatinine. There was no statistically significant difference between the groups in total oxidant and antioxidant levels.

CONCLUSIONS

Dexpanthenol did not have significant effect on oxidative stress of acute kidney injury on this rat model. However, it has ameliorated serum Cys-C levels and histopathological findings of CIN.

[Acute kidney injury: from creatinine to KIM‑1?]

In addition to the early detection of an acute kidney injury (AKI), several problems or questions have to be addressed. These include the identification of the etiology, the severity (functional or structural), the prognosis (recovery or transition to chronic renal failure), the course of the disease (dialysis or not), and the identification of specific treatment options for AKI. The following article provides an overview of established and new AKI biomarkers as well as an outlook on the potential of future biomarker-associated models of AKI.

Activin A: a novel urinary biomarker of renal impairment in multiple myeloma

Renal impairment (RI) is a common complication of multiple myeloma (MM) that significantly affects treatment efficacy and mortality. However, no useful biomarkers for early detection of renal damage in MM exist. Reports indicate that activin A, a multifunctional cytokine of the TGF-β superfamily, is involved in the development and progression of various kidney diseases. In the present study, we measured urinary activin A levels in patients with newly diagnosed MM (NDMM) (n=41), smoldering MM (SMM) (n=10), and monoclonal gammopathy of undetermined significance (MGUS) (n=28), including monoclonal gammopathy of renal significance (MGRS), and assessed the correlation between urinary activin A and several clinical parameters. Urinary activin A, undetectable in healthy volunteers, was significantly increased in NDMM patients but not in patients with SMM and MGUS (97.3, 25.0, and 6.61 mg/gCr, respectively, P<0.05). In all patients with NDMM, urinary activin A levels were significantly reduced after initial treatment regardless of the therapy regimen. There was a significant correlation of urinary activin A with spot urinary protein level (P<0.001) and serum M-protein (P=0.029) but not with estimated glomerular filtration rate (eGFR), serum creatinine (Cr), N-acetyl-glucosaminidase (NAG), and serum activin A level. Histological analysis using renal biopsy samples revealed that activin A, which was absent from normal kidneys, was detected in the renal tubular cells of patients with MGRS. These data suggest that urinary activin A reflects tubular injury in MM and might aid the early detection of RI in plasma cell neoplasms.

Biomarkers for acute kidney injury in decompensated cirrhosis: A prospective study

AIM

Acute kidney injury (AKI) is a frequent complication in cirrhotic patients. As serum creatinine is a poor marker of renal function in this population, we aimed to study the utility of several biomarkers in this context.

METHODS

A prospective study was conducted in hospitalized patients with decompensated cirrhosis. Serum creatinine (SCr), Cystatin C (CystC), NGAL and urinary NGAL, KIM-1, protein, albumin and sodium were measured on three separate occasions. Renal resistive index (RRI) was obtained. We analyzed the value of these biomarkers to determine the presence of AKI, its aetiology [prerenal, acute tubular necrosis (ATN), or hepatorenal (HRS)], its severity and a composite clinical outcome at 30 days (death, dialysis and intensive care admission).

RESULTS

We included 105 patients, of which 55 had AKI. SCr, CystC, NGAL (plasma and urinary), urinary sodium and RRI at inclusion were independently associated with the presence of AKI. SCr, CystC and plasma NGAL were able to predict the subsequent development of AKI. Pre-renal state showed lower levels of SCr, NGAL (plasma and urinary) and RRI. ATN patients had high levels of NGAL (plasma and urinary) as well as urinary protein and sodium. HRS patients presented an intermediate pattern. All biomarkers paralleled the severity of AKI. SCr, CystC and plasma NGAL predicted the development of the composite clinical outcome with the same performance as the MELD score.

CONCLUSIONS

In patients with decompensated cirrhosis, early measurement of renal biomarkers provides valuable information on AKI aetiology. It could also improve AKI diagnosis and prognosis.

[Laboratory tests for kidney disease]

Kidney diseases are among the most frequently reported diseases with a poor prognosis that are diagnosed too late. According to current Kidney Disease Improving Global Outcomes (KDIGO) guidelines, diagnosis and risk stratification are mainly based on functional markers (creatinine and cystatin C), which are used to determine the estimated glomerular filtration rate (eGFR) and the analysis of urinary albumin excretion as a marker of kidney damage. These methods have limitations that can complicate the interpretation of the results and can lead to a delay of the diagnosis as well as to a misinterpretation of the prognosis. Therefore, new damage markers are required that sensitively and specifically detect kidney damage and enable targeted treatment. Urinalysis complements the laboratory diagnostic spectrum of diseases of the kidneys and urinary tract. It is mainly used for screening and provides important information on localization (renal/postrenal) and differentiation of kidney diseases (glomerular/tubulointerstitial).

The future for diagnostic tests of acute kidney injury in critical care: evidence synthesis, care pathway analysis and research prioritisation

BACKGROUND

Acute kidney injury (AKI) is highly prevalent in hospital inpatient populations, leading to significant mortality and morbidity, reduced quality of life and high short- and long-term health-care costs for the NHS. New diagnostic tests may offer an earlier diagnosis or improved care, but evidence of benefit to patients and of value to the NHS is required before national adoption.

OBJECTIVES

To evaluate the potential for AKI in vitro diagnostic tests to enhance the NHS care of patients admitted to the intensive care unit (ICU) and identify an efficient supporting research strategy.

DATA SOURCES

We searched ClinicalTrials.gov, The Cochrane Library databases, Embase, Health Management Information Consortium, International Clinical Trials Registry Platform, MEDLINE, metaRegister of Current Controlled Trials, PubMed and Web of Science databases from their inception dates until September 2014 (review 1), November 2015 (review 2) and July 2015 (economic model). Details of databases used for each review and coverage dates are listed in the main report.

REVIEW METHODS

The AKI-Diagnostics project included horizon scanning, systematic reviewing, meta-analysis of sensitivity and specificity, appraisal of analytical validity, care pathway analysis, model-based lifetime economic evaluation from a UK NHS perspective and value of information (VOI) analysis.

RESULTS

The horizon-scanning search identified 152 potential tests and biomarkers. Three tests, Nephrocheck^® (Astute Medical, Inc., San Diego, CA, USA), NGAL and cystatin C, were subjected to detailed review. The meta-analysis was limited by variable reporting standards, study quality and heterogeneity, but sensitivity was between 0.54 and 0.92 and specificity was between 0.49 and 0.95 depending on the test. A bespoke critical appraisal framework demonstrated that analytical validity was also poorly reported in many instances. In the economic model the incremental cost-effectiveness ratios ranged from £11,476 to £19,324 per quality-adjusted life-year (QALY), with a probability of cost-effectiveness between 48% and 54% when tests were compared with current standard care.

LIMITATIONS

The major limitation in the evidence on tests was the heterogeneity between studies in the definitions of AKI and the timing of testing.

CONCLUSIONS

Diagnostic tests for AKI in the ICU offer the potential to improve patient care and add value to the NHS, but cost-effectiveness remains highly uncertain. Further research should focus on the mechanisms by which a new test might change current care processes in the ICU and the subsequent cost and QALY implications. The VOI analysis suggested that further observational research to better define the prevalence of AKI developing in the ICU would be worthwhile. A formal randomised controlled trial of biomarker use linked to a standardised AKI care pathway is necessary to provide definitive evidence on whether or not adoption of tests by the NHS would be of value.

STUDY REGISTRATION

The systematic review within this study is registered as PROSPERO CRD42014013919.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Disposable electrochemical immunosensor for analysis of cystatin C, a CKD biomarker

Specific monitoring of cystatin C (CysC) levels in biological fluids is critical for diagnosis, treatment and mechanistic understanding of a spectrum of diseases, particularly chronic kidney disease (CKD). Despite evidences that CysC correlates with the high risk and/or progression of CKD, its use in clinical practice is still scarce. In this context, we report the development of a simple and sensitive immunosensor for the detection of CysC. The biosensor combines the technology of cost-effective screen-printed electrodes with the high specificity of a sandwich immunoassay. Optimized conditions showed that the sensor operates in a linear range between 10 and 100 ng mL^-1, with a detection limit and a sensitivity of 6.0 ng mL^-1 and 6.4 ± 0.3 μA ng mL^-1 cm^-2, respectively. Moreover, the sensor provided precise results (RSD ≤ 6.2%) and the quantification of CysC in CKD serum samples revealed to be in agreement with the values obtained by a particle-enhanced nephelometric immunoassay. In this light, the proposed immunosensor qualifies for clinical application, constituting a step forward in the development of fast, sensitive and cost-effective diagnostic tools that can improve the current medical care settings of CKD patients.

Proteomics and Metabolomics for AKI Diagnosis

Acute kidney injury (AKI) is a severe and frequent condition in hospitalized patients. Currently, no efficient therapy of AKI is available. Therefore, efforts focus on early prevention and potentially early initiation of renal replacement therapy to improve the outcome in AKI. The detection of AKI in hospitalized patients implies the need for early, accurate, robust, and easily accessible biomarkers of AKI evolution and outcome prediction because only a narrow window exists to implement the earlier-described measures. Even more challenging is the multifactorial origin of AKI and the fact that the changes of molecular expression induced by AKI are difficult to distinguish from those of the diseases associated or causing AKI as shock or sepsis. During the past decade, a considerable number of protein biomarkers for AKI have been described and we expect from recent advances in the field of omics technologies that this number will increase further in the future and be extended to other sorts of biomolecules, such as RNAs, lipids, and metabolites. However, most of these biomarkers are poorly defined by their AKI-associated molecular context. In this review, we describe the state-of-the-art tissue and biofluid proteomic and metabolomic technologies and new bioinformatics approaches for proteomic and metabolomic pathway and molecular interaction analysis. In the second part of the review, we focus on AKI-associated proteomic and metabolomic biomarkers and briefly outline their pathophysiological context in AKI.

Serum cystatin C as an indicator for early detection of diabetic nephropathy in type 2 diabetes mellitus

BACKGROUND

Diabetes mellitus (DM) refers to a group of common metabolic disorders that share the phenotype of hyperglycemia. The metabolic dysregulations associated with DM causes secondary pathophysiological changes in multiple organ systems which result in various complications, responsible for the morbidity and mortality associated with the disease.

METHODS

The present study was carried out on 40 patients with type 2 diabetes mellitus, who were recruited from those attending outpatient clinic and inpatient of Internal Medicine Department at The National Institute of Diabetes and Endocrinology from January 2017 to june 2017.

RESULTS

The mean Cystatin C values in Group I were 0.74, group II were 1.07. and in Group III were 3.25, The results show that the Cystatin C values were raised even in the patients with Normoalbuminuria with GFR ≥90 whom clinical albuminuria had not yet started.

CONCLUSIONS

serum Cystatin C may be considered as an early marker, than microalbuminuria and serum creatinine, the commonly used marker for nephropathy, for declining renal function, in diabetic subjects. Further studies in larger population are needed to confirm this result.

Fiend and friend in the renin angiotensin system: An insight on acute kidney injury

Besides assisting the maintenance of blood pressure and sodium homeostasis, the renin-angiotensin system (RAS) plays a pivotal role in pathogenesis of acute kidney injury (AKI). The RAS is equipped with two arms i) the pressor arm composed of Angiotensin II (Ang II)/Angiotensin converting enzyme (ACE)/Angiotensin II type 1 receptor (AT1R) also called conventional RAS, and ii) the depressor arm consisting of Angiotensin (1-7) (Ang 1-7)/Angiotensin converting enzyme 2 (ACE2)/MasR known as non-conventional RAS. Activation of conventional RAS triggers oxidative stress, inflammatory, hypertrophic, apoptotic, and pro-fibrotic signaling cascades which promote AKI. The preclinical and clinical studies have reported beneficial as well as deleterious effects of RAS blockage either by angiotensin receptor blocker or ACE inhibitor in AKI. On the contrary, the depressor arm opposes the conventional RAS, has beneficial effects on the kidney but has been less explored in pathogenesis of AKI. This review focuses on significance of RAS in pathogenesis of AKI and provides better understanding of novel and possible therapeutic approaches to combat AKI.

Are there any new reliable markers to detect renal injury in obese children?

AIM

The aim of this study was to examine the serum and urine levels of kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), osteopontin (OPN), matrix metalloproteinase-9 (MMP-9), and serum Cystatin-C to determine the renal effect of obesity in obese children.

METHODS

Seventy-two obese and 35 non-obese healthy children were included in this study. Blood pressure (BP) was evaluated with office measurement. Creatinine, cystatin C, lipids, fasting glucose, and insulin levels were measured, and homeostasis model assessment -insulin resistance (HOMA-IR) was calculated. The urine albumin/creatinine ratio was calculated. The serum and urine KIM-1, NGAL, OPN, and MMP-9 levels were measured.

RESULTS

Serum cystatin-C, triglyceride, and homeostasis model assessment-insulin resistance (HOMA-IR) index were found to be significantly higher in the obese group (p = .0001), and high-density lipoprotein (HDL) cholesterol was found to be significantly lower (p = .019) in the obese group. No significant differences were found in serum KIM-1, NGAL, OPN or MMP-9 levels between groups (p > .05). No significant differences were found in urine KIM-1 and MMP-9 levels (p > .05), Urine NGAL, and OPN levels were found significantly higher in obese groups (p < .05).

CONCLUSIONS

According to our results, although serum KIM-1, NGAL, OPN, MMP-9, and urine MMP-9, urine KIM-1 do not appear to be ideal markers to evaluate renal injury in the early period of obesity, the serum levels of cystatin C and urine NGAL, urine OPN can be used as a good marker for assessing the renal effect of obesity which can lead end stage renal disease in pediatric population.

Subclinical acute kidney injury is associated with adverse outcomes in critically ill neonates and children

BACKGROUND

Research on acute kidney injury (AKI) has focused on identifying early biomarkers. However, whether AKI could be diagnosed in the absence of the classic signs of clinical AKI and whether the condition of subclinical AKI, identified by damage or functional biomarkers in the absence of oliguria or increased serum creatinine (sCr) levels, is clinically significant remains to be elucidated in critically ill children. The aims of the study were to investigate the associations between urinary cystatin C (uCysC) levels and AKI and mortality and to determine whether uCysC-positive subclinical AKI is associated with adverse outcomes in critically ill neonates and children.

METHODS

In this prospective cohort study, uCysC levels were serially measured during the first week after intensive care unit (ICU) admission in a heterogeneous group of patients (n = 510) presenting to a tertiary neonatal and pediatric ICU. The diagnosis of neonatal AKI that developed during the first week after admission was based on neonatal KDIGO criteria or sCr >1.5 mg/dL, and pediatric AKI was based on Kidney Disease: Improving Global Outcomes (KDIGO) criteria. The term "uCysC(-)" or "uCysC(+)", indicating the absence or presence of tubular injury, was defined by the optimal peak uCysC cutoff value for predicting ICU mortality.

RESULTS

The initial and peak uCysC levels were significantly associated with AKI and mortality, and had an area under the receiver operating characteristic curve of 0.76 and 0.81, respectively, for predicting mortality. At the optimal cutoff value of 1260 ng/mg uCr, the peak uCysC displayed sensitivity of 79.2% and specificity of 72.3% for predicting mortality. Among all patients, 130 (25.5%) developed uCysC(+)/AKI(-) status during the first week after admission. The adjusted odds ratio for patients with uCysC(+)/AKI(-) status in association with an increased risk of mortality compared with that for patients with uCysC(-)/AKI(-) was 9.34 (P < 0.001). Patients with uCysC(+)/AKI(-) spent 2.8 times as long in the ICU as those with uCysC(-)/AKI(-) (P < 0.001).

CONCLUSIONS

Both initial and peak uCysC levels are associated with AKI and mortality and are independently predictive of mortality in critically ill neonates and children. Subclinical AKI may occur without detectable loss of kidney function, and uCysC-positive subclinical AKI is associated with worse clinical outcomes in this population.

Telluric Acid Ameliorates Endotoxemic Kidney Injury in Mice: Involvement of TLR4, Nrf2, and PI3K/Akt Signaling Pathways

Being one of the most abundant trace elements in the human body, the therapeutic potential of tellurium-based compounds has been a target of interest. Recent reports denoted their redox-modulating and anti-inflammatory activities in experimental endotoxemia. However, their potential nephroprotective effect against endotoxemic kidney injury is yet to be elucidated. This study investigated the possible renoprotective effect of telluric acid (TEL) against lipopolysaccharide (LPS)-induced acute kidney injury (AKI) in mice, targeting toll-like receptor 4 (TLR4), phosphoinositide 3-kinase (PI3K)/Akt, and nuclear factor-erythroid 2-related factor-2 (Nrf2) pathways as possible mechanistic contributors to TEL's effect. AKI was induced by LPS (2 mg/kg). TEL (60 μg/kg; i.p.) was administered once daily for seven consecutive days before LPS injection. Pretreatment with TEL alleviated LPS-induced AKI as evidenced by the hampered serum levels of creatinine and cystatin C. TEL also opposed LPS-induced elevation in renal kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, nuclear factor-kappa B p65, interleukin-1β, and thiobarbituric acid-reactive substance contents. This was accompanied by a replenishment of renal glutathione, transcriptional upregulation of Nrf2, enhancement of heme oxygenase-1 activity, and a marked upregulation of phospho-PI3K and phospho-Akt protein expressions. Histopathological findings corroborated with the amendment of biochemical parameters. In view of these findings, we may conclude that TEL pretreatment purveyed novel nephroprotective effects against endotoxemic kidney injury, which might be partly attributed to the modulation of TLR4, PI3K/Akt, and Nrf2 signaling pathways and may hence provide a valuable asset for the management of endotoxemic renal complications.

Creatinine Versus Cystatin C: Differing Estimates of Renal Function in Hospitalized Veterans Receiving Anticoagulants

BACKGROUND

Current practice in anticoagulation dosing relies on kidney function estimated by serum creatinine using the Cockcroft-Gault equation. However, creatinine can be unreliable in patients with low or high muscle mass. Cystatin C provides an alternative estimation of glomerular filtration rate (eGFR) that is independent of muscle.

OBJECTIVE

We compared cystatin C-based eGFR (eGFR_cys) with multiple creatinine-based estimates of kidney function in hospitalized patients receiving anticoagulants, to assess for discordant results that could impact medication dosing.

DESIGN

Retrospective chart review of hospitalized patients over 1 year who received non-vitamin K antagonist anticoagulation, and who had same-day measurements of cystatin C and creatinine.

PARTICIPANTS

Seventy-five inpatient veterans (median age 68) at the San Francisco VA Medical Center (SFVAMC).

MAIN MEASURES

We compared the median difference between eGFR by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) study equation using cystatin C (eGFR_cys) and eGFRs using three creatinine-based equations: CKD-EPI (eGFR_EPI), Modified Diet in Renal Disease (eGFR_MDRD), and Cockcroft-Gault (eGFR_CG). We categorized patients into standard KDIGO kidney stages and into drug-dosing categories based on each creatinine equation and calculated proportions of patients reclassified across these categories based on cystatin C.

KEY RESULTS

Cystatin C predicted overall lower eGFR compared to creatinine-based equations, with a median difference of - 7.1 (IQR - 17.2, 2.6) mL/min/1.73 m² versus eGFR_EPI, - 21.2 (IQR - 43.7, - 8.1) mL/min/1.73 m² versus eGFR_MDRD, and - 25.9 (IQR - 46.8, - 8.7) mL/min/1.73 m² versus eGFR_CG. Thirty-one to 52% of patients were reclassified into lower drug-dosing categories using cystatin C compared to creatinine-based estimates.

CONCLUSIONS

We found substantial discordance in eGFR comparing cystatin C with creatinine in this group of anticoagulated inpatients. Our sample size was limited and included few women. Further investigation is needed to confirm these findings and evaluate implications for bleeding and other clinical outcomes.

NIH TRIAL REGISTRY NUMBER

Not applicable.

Biomarkers in acute kidney injury (AKI)

Acute kidney injury is common in critically ill patients and portends a significant impact on mortality, progressive chronic kidney disease, and cardiovascular disease and mortality. Though most physicians alter therapy depending on changes in serum creatinine, this often represents delayed intervention. Various AKI biomarkers have been discovered and validated to improve timely detection, differentiation and stratification into risk groups for progressive renal decline, need for renal replacement therapy or death. This chapter will review AKI biomarkers validated over the past decade. We also describe the clinical performance of the biomarkers. We suggest that using AKI biomarkers to complement serum creatinine (or cystatin C) and urine output will better integrate patient care through earlier recognition and clinical outcome prediction after AKI.