Can admission serum cystatin C level be an early marker subclinical acute kidney injury in critical care patients?

Advances in the study of subclinical AKI biomarkers

Acute kidney injury (AKI) is a prevalent and serious illness in all clinical departments, with a high morbidity and death rate, particularly in intensive care units, where prevention and treatment are crucial. As a result, active prevention, early detection, and timely intervention for acute kidney injury are critical. The current diagnostic criteria for acute kidney injury are an increase in serum creatinine concentration and/or a decrease in urine output, although creatinine and urine output merely reflect changes in kidney function, and AKI suggests injury or damage, but not necessarily dysfunction. The human kidney plays a crucial functional reserve role, and dysfunction is only visible when more than half of the renal mass is impaired. Tubular damage markers can be used to detect AKI before filtration function is lost, and new biomarkers have shown a new subset of AKI patients known as “subclinical AKI.” Furthermore, creatinine and urine volume are only marginally effective for detecting subclinical AKI. As a result, the search for new biomarkers not only identifies deterioration of renal function but also allows for the early detection of structural kidney damage. Several biomarkers have been identified and validated. This study discusses some of the most promising novel biomarkers of AKI, including CysC, NGAL, KIM-1, lL-18, L-FABP, IGFBP7, TIMP-2, Clusterin, and Penkid. We examine their performance in the diagnosis of subclinical AKI, limitations, and future clinical practice directions.

Serum Cystatin C Level Monitoring for Intervention Opportunity of CBP in Children with Severe Sepsis

Objective

The aim of this study is to investigate the instruction value of the serum cystatin C (Cys C) level monitoring for intervention opportunity of continuous blood purification technology (CBP) in children with severe sepsis.

Methods

67 children with severe sepsis in the pediatric intensive care unit (PICU) with CBP treatment were retrospectively selected from May 2016 to April 2020. According to the time intervals between the time point of serum Cys C level began to increase (>15 mg/L) and the time point of CBP began, all children were divided into group A (<24 h, 29 cases), group B (24–48 h, 22 cases), and group C (>48 h, 16 cases). The children's general characteristics, vital signs, biochemical parameters, acute physiology and chronic health evaluation (APACHE II), and sequential organ failure assessment (SOFA) scores were evaluated. The influence factors of prognosis of children with severe sepsis were analyzed by multivariate regression analysis.

Results

The intervals between the time point of PICU hospitalization and the time point of CBP began and the times of CBP in group A were significantly more than those in group B and C (P < 0.05). There was no statistically significant duration of CBP among three groups (P > 0.05). After follow-up of 28 d, there was no significant difference on the occurrence of coagulation disorders and hypovolemic shock induced by CBP among three groups (P > 0.05). However, the mortality of children in group A was lower than that in group C (P < 0.05). Children in group A had lower APACHE II scores, SOFA scores, serum K+, blood urea nitrogen (BUN), serum creatine (SCr), partial pressure of carbon dioxide (PCO₂), and higher partial pressure of oxygen (PO₂) than those of children in group C after CBP. (P < 0.05). SOFA scores ≥5 after CBP treatment and the time intervals between the time point of serum Cys C level began to increase (>15 mg/L) and the time point of CBP began ≥24 h were the independent influence factors on the prognosis by multivariate regression analysis.

Conclusion

There are significant evidences that continuous blood purification technology within 24 h of serum Cys C level may better control the condition of children with severe sepsis.

Early prediction of COVID-19-associated Acute Kidney Injury: Are serum NGAL and serum Cystatin C levels better than serum creatinine?

Background

Coronavirus disease-2019 (COVID-19) is associated with a high risk of acute kidney injury (AKI), often requiring renal replacement therapy (RRT). Serum Cystatin C (sCysC) and serum Neutrophil Gelatinase-Associated Lipocalin (sNGAL) are emerging biomarkers for kidney injury, and were suggested to be superior to serum creatinine (sCr) in several clinical settings. Moreover, elevated sCysC is associated with disease severity and mortality in COVID-19. We aimed to assess the utility of sCysC and sNGAL for predicting COVID-19-associated AKI, need for RRT, and need for intensive care unit (ICU) admission, when measured at presentation to the emergency department (ED).

Methods

Patients presenting to the ED with laboratory-confirmed COVID-19 were included. The primary outcome was development of COVID-19-associated AKI, while the secondary outcomes were need for RRT and ICU admission.

Results

Among 52 COVID-19 patients, 22 (42.3%) developed AKI with 8/22 (36.4%) requiring RRT. Both sCr and sCysC demonstrated excellent performance for predicting AKI (AUC, 0.86 and 0.87, respectively) and need for RRT (AUC, 0.94 and 0.95, respectively). sNGAL displayed acceptable performance for predicting AKI (AUC, 0.81) and need for RRT (AUC, 0.87).

Conclusions

SCr and sCysC measured at ED presentation are both highly accurate predictors of AKI and need for RRT, whereas sNGAL demonstrated adequate diagnostic performance. While sCyC was previously shown to be superior to sCr as a diagnostic biomarker of kidney injury in certain etiologies, our findings demonstrate that sCr is comparable to sCyC in the context of predicting COVID-19-associated AKI. Given the high sensitivity of these biomarkers for predicting the need for RRT, and as sCysC is associated with mortality in COVID-19 patients, we recommend their measurement for enabling risk stratification and early intervention.

NGAL, albumin and cystatin C during cisplatin therapy

Cisplatin is a commonly used chemotherapeutic drugs. It is known for its nephrotoxic side effects with an increased risk of acute kidney injury. Finding of clinically feasible cisplatin nephrotoxicity markers is of importance. In our study, we compared neutrophil gelatinase-associated lipocalin (NGAL) in serum and urine, the estimated glomerular filtration rate (based on serum cystatin C) and urine albumin as markers of nephrotoxicity. The study involved 11 men and 9 women (mean ± SD age 58.2±9.5 years) with different malignancies treated with cisplatin in four cycles of chemotherapy (I - IV). Samples 0-4 were taken before, immediately after, in 3, 6 and 24 hours after administering chemotherapy. We detected significant increase of ACR in Sample 2 (p=0.03) and decrease of eGFR in Sample 4 (p=0.03) up to 24 hours after cisplatin administration in the first chemotherapy cycle only. When cumulative effect of cisplatin was assessed, significantly increased values of urine albumin (vs cycle I) were found in Sample 0 (p=0.00058), 1 (p=0.00256), 2 (p=0.00456), 3 (p=0.00006) and 4 (p=0.00319) in cycles II to IV. We found a correlation between values of urine NGAL and urine albumin (r=0.68, p<0.0001). In conclusion, urine albumin was the only measured marker that consistently and statistically significantly increased after cisplatin containing chemotherapy cycles.

Time-dependent changes in kidney injury biomarkers in patients receiving multiple cycles of cisplatin chemotherapy

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KIM-1, calbindin, and TFF3 are increased in urine of patients prescribed cisplatin.

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KIM-1 concentrations remain elevated with subsequent cisplatin treatment cycles.

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Calbindin concentrations increased only during initial cycles of cisplatin chemotherapy.

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TFF3 increased similarly on both cycles and returned to baseline in between.

Proteins secreted into urine following tubular injury are being increasingly used as biomarkers of clinical and subclinical nephrotoxicity. In the present study, we sought to characterize the time-dependent urinary excretion of three promising biomarkers, kidney injury molecule-1 (KIM-1), calbindin, and trefoil factor 3 (TFF3), during two different chemotherapy cycles in 27 patients with solid tumors prescribed the anticancer drug cisplatin (≥25 mg/m²). Urinary biomarkers were evaluated at Days 3 and 10 during an initial and a subsequent cycle of cisplatin chemotherapy. Longitudinal analyses compared the mean difference estimations for biomarker concentrations during and across the initial and subsequent cycles of cisplatin treatment. Traditional biomarkers including serum creatinine, estimated glomerular filtration rate, and blood urea nitrogen were unchanged during and across both cycles of cisplatin therapy. In response to the initial cycle, urinary KIM-1 concentrations increased from baseline and remained elevated through a subsequent cycle of cisplatin chemotherapy. By comparison, urinary levels of calbindin were elevated 10 days after the initial cisplatin treatment, but largely unchanged by cisplatin exposure in a subsequent cycle. Early elevations in urinary TFF3 at 3 days after cisplatin administration were observed consistently in both the initial and subsequent cycle of cisplatin treatment. In conclusion, the longitudinal assessment of biomarker performance in the same cohort of oncology patients reveals different patterns of urinary excretion between initial and subsequent cycles of cisplatin-containing chemotherapy. These data add novel cycle-dependent insight to the growing literature addressing the ability of urinary biomarkers to detect subclinical renal injury in patients receiving cisplatin.

Use of Both Serum Cystatin C and Creatinine as Diagnostic Criteria for Cardiac Surgery-Associated Acute Kidney Injury and Its Correlation with Long-Term Major Adverse Events

BACKGROUND/AIMS

Cardiac surgery-associated acute kidney injury (CSA-AKI) was traditionally defined as an increase in serum creatinine (sCr) after cardiac surgery. Recently, serum cystatin C (sCyC) has been proposed to be a better biomarker in the prediction of AKI. The clinical utility and performance of combining sCyC and sCr in patients with AKI, particularly for the prediction of long-term outcomes, remain unknown.

METHODS

We measured sCyC together with sCr in 628 patients undergoing cardiac surgery. sCyC and sCr were assessed at baseline and 24 and 48 h after surgery. CSA-AKI determined by sCr (CSA-AKIsCr) was defined as an sCr increase greater than 0.3 mg/dL or 50% from baseline. Major adverse events (MAEs; including death of any cause and dialysis) at 3 years were assessed.

RESULTS

CSA-AKIsCr developed in 178 patients (28.3%). Three-year follow-up was available for 621 patients; MAEs occurred in 42 patients (6.8%). An increase in sCyC concentration ≥30% within 48 h after surgery was detected in 228 patients (36.3%). This was the best sCyC cutoff for CSA-AKIsCr detection (negative predictive value = 88.8%, positive predictive value = 58.3%). To evaluate the use of both sCyC and sCr as CSA-AKI diagnostic criteria, we stratified patients into 3 groups: non-CSA-AKI, CSA-AKI detected by a single marker, and CSA-AKI detected by both markers. By multivariable logistic regression analysis, the independent predictors of MAEs at 3 years were group 2 (non-CSA-AKI group as the reference, CSA-AKI detected by a single marker: odds ratio [OR] = 3.48, 95% confidence interval [CI]: 1.27-9.58, p = 0.016), group 3 (CSA-AKI detected by both markers: OR = 5.12, 95% CI: 2.01-13.09; p = 0.001), and baseline glomerular filtration rate (OR = 2.24; 95% CI: 1.27-3.95; p = 0.005).

CONCLUSION

Combining sCyC and sCr to diagnose CSA-AKI would be beneficial for risk stratification and prognosis in patients after cardiac surgery.

No Differences in Renal Function between Balanced 6% Hydroxyethyl Starch (130/0.4) and 5% Albumin for Volume Replacement Therapy in Patients Undergoing Cystectomy: A Randomized Controlled Trial

BACKGROUND

The use of artificial colloids has declined in critical care, whereas they are still used in perioperative medicine. Little is known about the nephrotoxic potential in noncritically ill patients during routine surgery. The objective of this trial was to evaluate the influences of albumin 5% and balanced hydroxyethyl starch 6% (130/0.4) on renal function and kidney injury.

METHODS

One hundred urologic patients undergoing elective cystectomy were randomly assigned for this prospective, single-blinded, controlled study with two parallel groups to receive either albumin 5% or balanced hydroxyethyl starch 6% (130/0.4) as the only perioperative colloid. The primary endpoint was the ratio of serum cystatin C between the last visit at day 90 and the first preoperative visit. Secondary endpoints were estimated glomerular filtration rate and serum neutrophil gelatinase-associated lipocalin until the third postoperative day and risk, injury, failure, loss, and end-stage renal disease criteria at postoperative days 3 and 90.

RESULTS

The median cystatin C ratio was 1.11 (interquartile range, 1.01 to 1.23) in the albumin and 1.08 (interquartile range, 1.00 to 1.20) in the hydroxyethyl starch group (median difference = 0.03; 95% CI, -0.09 to 0.08; P = 0.165). Also, there were no significant differences concerning serum cystatin C concentrations; estimated glomerular filtration rate; risk, injury, failure, loss, and end-stage renal disease criteria; and neutrophil gelatinase-associated lipocalin. Infusion requirements, transfusion rates, and perioperative hemodynamics were similar in both groups.

CONCLUSIONS

With respect to renal function and kidney injury, this study indicates that albumin 5% and balanced hydroxyethyl starch 6% have comparable safety profiles in noncritically ill patients undergoing major surgery.

Clinical significance of novel biomarker NGAL in early diagnosis of acute renal injury

The present study investigated the clinical significance of the novel biomarker neutrophil gelatinase-associated lipocalin (NGAL) for the early diagnosis of acute renal injury (AKI). Thirty-eight critically ill patients with acute renal injury treated at Zhengzhou No. 7 People's Hospital between December 2015 and November 2016 served as the AKI group (observation group). At the same time, 38 critically ill patients without acute renal injury were also selected as the non-AKI group (control group). Serum NGAL and creatinine (SCr) levels were measured by enzyme-linked immunosorbent assay (ELISA) at 2, 8, 12 and 24 h post-operation, whereas particle-enhanced turbidimetric immunoassay (PETIA) was used to quantify the levels of cysteine protease inhibitor cystatin C (CysC) in serum at 2, 8, 12 and 24 h post-operation. The correlations between indicators were also analyzed, with ROC curves used to evaluate the diagnostic values of NGAL, SCr and CysC in AKI. No significant differences in SCr levels were found between the two groups at different time-points after operation (P>0.05), but NGAL and CysC levels in the observation group were significantly higher than in the control group (P<0.05). Pearson correlation coefficient analysis showed NGAL and CysC were positively correlated with Scr levels. For NGAL in early diagnosis, the area under the AKI curve was 0.904, the sensitivity was 90.2% and the specificity was 89.5%; for CysC in early diagnosis, the area under the AKI curve was 0.806, the sensitivity was 79.2% and the specificity was 78.5%; for SCr in early diagnosis, the area under the AKI curve was 0.634, the sensitivity was 64.2% and the specificity was 62.5%. Therefore, NGAL demonstrated a satisfactory early predictive value for AKI and can be used as a biomarker for early AKI diagnosis.

The diagnostic value of serum creatinine and cystatin c in evaluating glomerular filtration rate in patients with chronic kidney disease: a systematic literature review and meta-analysis

BACKGROUND

Serum biomarkers, such as serum creatinine (SCr) and serum cystatin C (SCysC), have been widely used to evaluate renal function in patients who have chronic kidney disease (CKD).

OBJECTIVE

This article aims to assess the value of determining SCr and SCysC levels in patients that have long-term kidney disease. Approaches: MEDLINE, EmBase, the Cochrane Library and other databases were searched using both MeSH terms and text words to collect research that assessed the diagnostic value of using SCr and SCysC to evaluate Glomerular Filtration Rate (GFR) in patients with CKD. Data were converted into fourfold tables. Summary Receiver Operating Characteristic Curves and meta-analyses were accomplished via Meta-Disc version 1.4.

RESULTS

In total, 21 relevant articles involving 3112 study subjects were included in our review. Results showed that the collective sensitivity for SCr and SCysC was 0.77 (95% CI: 0.69-0.84) and 0.87 (95% CI: 0.82-0.91), respectively. The pooled specificity for SCr and SCysC was 0.91 (95% CI: 0.86-0.94) and 0.87 (95% CI: 0.82-0.91), respectively. Subgroup analyses demonstrated that when GFR cut-off values are set to 60 (ml/min/1.73 m²), the pooled sensitivity is 0.94 (95% CI: 0.90-0.96) for SCysC and 0.75 (95% CI: 0.68-0.82) for SCr.

CONCLUSIONS

The diagnostical accuracy for impaired kidney function favors SCysC. Confidence intervals for the pooled sensitivity and specificity for SCr and SCysC overlap. However, SCysC is more sensitive for estimating GFR than SCr when GFR cut-off values are set to 60 (ml/min/1.73 m²).

Effects of differential-phase remote ischemic preconditioning intervention in laparoscopic partial nephrectomy: A single blinded, randomized controlled trial in a parallel group design

STUDY OBJECTIVE

There are two windows of protection for remote ischemic preconditioning (RIPC), an early (ERIPC) and a late-phase (LRIPC). While ERIPC has been well studied, works on LRIPC are relatively scarce, especially for the kidneys. We aimed to compare the effects of early-phase versus late-phase RIPC in patients with laparoscopic partial nephrectomy (LPN).

DESIGN

A randomized controlled study SETTING: The Second Affiliated Hospital of Anhui Medical University, 1 May 2012 to 30 October 2013 PATIENTS: Sixty-five ASA 1 to 2 patients scheduled for LPN were located randomly to ERIPC group, LRIPC group and CON group (control).

INTERVENTIONS

Three five-minute cycles of right upper limb ischaemia and reperfusion were performed after induction of anesthesia in ERIPC group. Patients in LRIPC group received similar treatment 24h before surgery, while control patients were not subjected to preconditioning.

MEASUREMENTS

Serum neutrophil gelatinase-associated lipocalin (NGAL) and serum cystatin C (CysC) were evaluated before the induction of anesthesia (0h), 2h (2h) and 6h (6h) after surgery. Unilateral glomerular filtration rates (GFR) were assessed before and after surgery to evaluate overall renal function.

MAIN RESULTS

Serum NGAL and CysC were significantly lower in ERIPC and LRIPC groups at 2h post-operation (P<0.001), 6h post-operation (P<0.001). Additionally, The GFR were significantly lower in ERIPC and LRIPC groups than in CON group at the 3rd month after surgery (P=0.019; P<0.001). Moreover, compared to the ERIPC group, concentration of NGAL and CysC in LRIPC group decreased to a greater extent, while GFR and the percentage of decrement was significantly less in the LRIPC group (P=0.016; P<0.001).

CONCLUSIONS

Regardless of early-phase or late-phase intervention, limb remote ischemic preconditioning confers protection on renal ischemia-reperfusion injury in patients with laparoscopic partial nephrectomy, and the late-phase protection is more prominent.

Predictive value of serum cystatin C for acute kidney injury in adults: a meta-analysis of prospective cohort trials

The role of serum cystatin C (Scys) for the detection of acute kidney injury (AKI) has not been fully discussed. This meta-analysis was aimed to investigate the overall diagnostic accuracy of Scys for AKI in adults, and further identify factors affecting its performance. Studies before Sept. 2016 were retrieved from PubMed, Embase, Web of Science and the Cochrane Library. A total of 30 prospective cohort studies (involving 4247 adults from 15 countries, 982 patients occurring AKI) were included. The revised Quality Assessment for Studies of Diagnostic Accuracy (QUADAS-2) tools demonstrated no significant bias had influenced the methodological quality of the included studies. Scys showed a high predictive power for all-cause AKI, that the area under the receiver operating characteristic curve was 0.89. The detailed assessment parameters, such as sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and diagnostic odds ratio for Scys were 0.82, 0.82, 4.6, 0.22 and 21, respectively. Although Scys could be slightly influenced by the following factors: settings, AKI diagnostic criteria, ethnicity, determination method, age and gender, these factors above did not reach statistically significance. In conclusion, Scys could be a vital promising marker to screen out AKI.

Biomarkers in critical illness: have we made progress?

Biomarkers have emerged as exemplary key players in translational medicine. Many have been assessed for timely recognition, early treatment, and adequate follow-up for a variety of pathologies. Biomarker sensitivity has improved considerably over the last years but specificity remains poor, in particular when two “marker-sensitive” conditions overlap in one patient. Biomarker research holds an enormous potential for diagnostic and prognostic purposes in postoperative and critically ill patients who present varying degrees of inflammation, infection, and concomitant (sub)acute organ dysfunction or failure. Despite a remarkable progress in development and testing, biomarkers are not yet ready for routine use at the bedside.