Prospective Comparison of Urinary Measured Creatinine Clearance With eGFR and Cystatin C Based Cis-eGFR, Including Kinetic eGFR in the Immediate Post-transplant Period With Prompt Allograft Function

BACKGROUND

The estimated glomerular filtration rate (eGFR) and kinetic estimated glomerular filtration rate (KeGFR) have not been compared, with urinary measured creatinine clearance (mCrCl) or serum cystatin C (CysC) eGFR, soon after kidney transplantation (KTx) with prompt primary function. This study aims to compare post-KTx, urinary mCrCl, and eGFR CysC with eGFR and KeGFR.

METHODS

Post-KTx, urine was collected every 12 hours from 25 of the 34 consenting subjects to calculate mCrCl and compare with Modification of Diet in Renal Disease (MDRD)-4, Jelliffe eGFR, Cockcroft-Gault creatinine clearance (CrCl), and KeGFR by Chen and Brater formulae. Serum CysC levels were also measured in the last 14 subjects to compare with creatinine, mCrCl, and eGFR CysC. RESULTS: At 12 to 96 hours post-KTx (n = 25), mCrCl was 55.8% to 13.6% higher than MDRD-4 eGFR. The mean CysC level (n = 14) was 58% to 14% lower than creatinine for up to 3.0 days post-KTx, with higher MDRD-4 eGFR CysC. Chen and Brater KeGFR were significantly lower than mCrCl and eGFR (Fig 1B, Table 1). Within 3 days post-KTx, a 50% decrease in creatinine provided ≥ 50 mL/min CrCl in 90% of cases (mean mCrCl 61.7 ± 22.8). This difference was greater when the initial creatinine was higher with the rapid decrease in creatinine.

CONCLUSIONS

(1) Post-KTx eGFR/KeGFR formulae underestimated mCrCl. (2) Serum CysC levels were lower than creatinine, corresponding with higher eGFR CysC. (3) A 50% decrease from initial serum creatinine; mean mCrCl was 61.7 ± 22.8 mL/min, and 90% of them have mCrCl > 50 mL/min. Post-KTx, until creatinine is stabilized, recipients are often receiving subtherapeutic dosing of renally adjusted medications. More prospective studies are necessary, including radioisotope clearance.

The clinical utility of cystatin C based eGFR in assessing renal function among HIV/AIDs patients on ART at Mildmay Uganda

BACKGROUND

In clinical practice, Measurement of estimated glomerular filtration rates (eGFR) is the gold standard assessing renal function the glomerular filtration rate often estimated from plasma creatinine. Several studies have shown Cystatin C based eGFR (Cys C) to be a better parameter for the diagnosis of impaired renal function. Cystatin C based eGFR has been proposed as a potential renal function marker but its use in HIV&AIDS patients has not been well evaluated.

METHODS

A cross sectional study was carried out on 914 HIV&AIDS patients on antiretroviral therapy (ART) attending Mildmay Uganda for care and treatment between January to March 2015. Serum Cystatin C based eGFR was measured using the particle enhanced immunoturbidimetric assay. Creatinine was analyzed using enzymatic Creatinine PAP method and creatinine clearance was calculated according to C&G.

RESULTS

The sensitivity of Cystatin C based eGFR was 15.1% (95% CI = 8.4, 24) with specificity 99.3% (95% CI = 98- 99.7). The positive and negative predictive values were 70.0% (95% CI 45.7-88.1) and 91.2% (95% CI 98.11-92.94) respectively. The positive likelihood ratio was 18.81 and negative likelihood ratio was 0.85. Cystatin C based eGFR had diagnostic accuracy of 90.7 and area under curve was 0.768.

CONCLUSION

Cystatin C based eGFR exhibited a high specificity and a high positive likelihood ratio in diagnosis of kidney disease among HIV&AIDS patients. Cystatin C based eGFR can be used as a confirmatory test.

Kidney manifestations of sarcoidosis

Renal involvement is a clinically relevant organ manifestation of sarcoidosis, leading to increased morbidity and complications. Although the exact incidence remains unknown, renal disease is likely to occur in up to one third of all sarcoidosis patients. Every patient with newly diagnosed sarcoidosis should receive a renal work-up and screening for disrupted calcium metabolism. Amid various forms of glomerulonephritis, granulomatous interstitial nephritis is the most common one, but it rarely leads to renal impairment. Histologically, granulomas can be absent. Nephrocalcinosis and nephrolithiasis are frequent forms when hypercalcaemia or hypercalciuria occur. Drugs used for treatment of systemic sarcoidosis can also cause renal damage. Due to its high heterogeneity, renal sarcoidosis can be difficult to treat. Glucocorticoids and various immunosuppressive treatments have been proven to be effective based on case series, but clinical trials are lacking. A treatment guideline for renal sarcoidosis is urgently needed. In this review article, we present an overview of the different forms of renal sarcoidosis and the diagnostic steps to confirm renal involvement; in addition, we provide insights on the management and available treatments. A better understanding regarding the pathogenesis of sarcoidosis is the key for the development of more specific, targeted therapies.

Cystatin C is associated with poor survival in amyotrophic lateral sclerosis patients

Background

Cystatin C (CysC) levels in amyotrophic lateral sclerosis (ALS) have been found changes, however, the associations between serum CysC levels and the progression and survival of ALS remain largely unknown.

Methods

A total of 1,086 ALS patients and 1,026 sex-age matched healthy controls (HCs) were enrolled in this study. Serum CysC, other renal function, and metabolic parameters were measured. Correlation analysis and binary logistic regression were used to explore the factors related to serum CysC. Kaplan-Meier curve and Cox regression model were used for survival analysis.

Results

CysC levels were significantly higher in ALS patients compared to HCs (0.94 vs. 0.85 mg/L, p < 0.001). Compared with ALS patients with lower CysC levels, those with higher CysC levels had an older age of onset, significantly lower ALSFRS-R scores (40.1 vs. 41.3, p < 0.001), a faster disease progression rate (0.75 vs. 0.67, p = 0.011), and lower frontal lobe function scores (15.8 vs. 16.1, p = 0.020). In the correlation analysis, CysC levels were significantly negatively correlated with ALSFRS-R scores (r = -0.16, p < 0.001). Additionally, ALS patients with higher CysC levels had significantly shorter survival time (40.0 vs. 51.8, p < 0.001) compared to patients with lower CysC levels. Higher CysC levels were associated with a higher risk of death in Cox analysis (HR: 1.204, 95% CI: 1.012-1.433). However, when treatment was included in the model, the result was no longer significant.

Conclusion

CysC levels in ALS patients were higher compared to HCs. Higher CysC levels were associated with greater disease severity, faster progression rate and shorter survival, needing early intervention.

A magnetic solid phase chemiluminescent immunoassay for quantification of Cystatin C in human serum

A chemiluminescent immunoassay for human serum Cystatin C (Cys C) was established using a direct-antibody sandwich model. The immunoassay kit uses magnetic separation technology, using magnetic particles as the reaction solid phase, alkaline phosphatase as the marker enzyme, and a new chemiluminescent substrate APLS as the substrate. It has the characteristics of high sensitivity and short reaction time. This product uses high-affinity antibodies, resulting in a high specificity. The established method showed good accuracy, uniformity, and stability. The limit of detection was 2.39 ng/mL. The intra-assay coefficient of variation (CV) was 3.36%-6.00%, the interassay CV was 4.12%-5.35%, and the recovery rate was 99.07%. The correlation coefficient (r) of Cys-C kit was 0.999388 ≥ 0.9900. The accuracy of the developed method was tested by automatic chemiluminescence instrument (P > 0.05). The lowest titer was 0.92500, and the highest was 1.10000. The developed method showed a good correlation with the product from Roche by comparing these two kits in 240 clinical samples from China. In total, 1392 clinical patient from China samples were measured using the reagent kit developed in this study.

Discrepancies between Cystatin C-Based and Creatinine-Based eGFR

BACKGROUND

Recent guidance suggests clinicians increase use of cystatin C for the estimation of GFR. Discrepant levels of creatinine- versus cystatin C-based eGFR (eGFRcr versus eGFRcys) can occur and might signify inaccurate estimation of GFR using creatinine alone. This study sought to enhance the knowledge of the risk factors and clinical implications of having a large eGFR discrepancy.

METHODS

Participants in the Atherosclerosis Risk in Communities Study, a prospective cohort study of US adults, were followed over 25 years. eGFR discrepancy was measured at five clinical visits and defined as eGFRcys either 30% lower or higher than eGFRcr, the current clinical standard of care. The associations between eGFR discrepancies and kidney-related laboratory parameters were assessed using linear and logistic regression and long-term adverse outcomes, including kidney failure, AKI, heart failure, and death, using Cox proportional hazards models.

RESULTS

Among 13,197 individuals (mean age 57 [SD 6] years, 56% women, 25% Black race), 7% had eGFRcys 30% lower than eGFRcr at visit 2 (1990-1992), and this proportion increased over time to 23% by visit 6 (2016-2017). By contrast, the percent with eGFRcys 30% higher than eGFRcr was relatively stable (3%-1%). Independent risk factors for having eGFRcys 30% lower than eGFRcr included older age, female sex, non-Black race, higher eGFRcr, higher body mass index, weight loss, and current smoking. Those with eGFRcys 30% lower than eGFRcr had more anemia and higher uric acid, fibroblast growth factor 23, and phosphate levels as well as higher risk of subsequent mortality, kidney failure, AKI, and heart failure compared with those with similar eGFRcr and eGFRcys values.

CONCLUSIONS

Having eGFRcys lower than eGFRcr was associated with worse kidney-related laboratory derangements and a higher risk of adverse health outcomes.

PODCAST

This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/CJASN/2023_09_08_CJN0000000000000217.mp3.

Assessment of Renal Function of Bodybuilders Using Anabolic Androgenic Steroids and Diet Supplements

Introduction Anabolic androgenic steroids (AAS) and diet supplements (DS) are frequently used by bodybuilders. In this specific group, increased muscle mass, the acute effects of exercise, and the use of creatine may affect the creatinine-based estimated glomerular filtration rate (eGFRcr), potentially leading to an underestimation of the GFR. Cystatin C equations offer a more accurate prediction of GFR that is independent of muscle mass. We aimed to assess the renal functions of bodybuilders who use both AAS+DS, as well as those who only use DS, by calculating the GFR based on cystatin C (eGFRcys) and also using a combination of cystatin C and creatinine (eGFRcys/cr). Methods The study included 12 bodybuilders using AAS+DS and 12 bodybuilders using DS. In both groups, serum cystatin C levels, eGFRcys, eGFRcys/cr, urine albumin excretion rates, urine protein excretion rates, and routine tests were examined. Results In AAS+DS users, the average duration of AAS use was 3.08±2.02 years, while for DS users, the duration of supplement use was 3.67±2.49 years. The spot urine albumin/creatinine and protein/creatinine ratios were higher in AAS+DS users (p<0.001 and p=0.006, respectively). Although eGFRcr was found to be similar in the AAS+DS and DS groups (119.67 ± 24.12 ml/min and 122.08 ± 18.03 ml/min, respectively; p=0.426), eGFRcys and the eGFRcys/cr ratio were significantly lower in the AAS+DS group compared to the DS group (eGFRcys: 120.67 ± 19.48 ml/min vs. 122.08 ± 18.03 ml/min, p=0.039; eGFRcys/cr: 121.83 ± 20.62 ml/min vs. 126.33 ± 21.163 ml/min, p= 0.036, respectively). Conclusion Cystatin-based GFR values were found to be significantly lower in AAS+DS users, and urinary albumin and protein excretion were considerably higher compared to DS users. Although these findings suggest a potential link between early kidney damage and the direct use of AAS, the topic requires further investigation.

Update on Assessment of Estimated Glomerular Filtration Rate in Patients With Cirrhosis

Kidney disease is associated with adverse outcomes in patients with cirrhosis including increased post-liver transplantation (LT) mortality. Therefore, diagnosis and staging of kidney disease are critical to timely implementation of treatment and have important implications for transplant eligibility. Serum creatinine (sCr) is a key component of the Model for End-Stage Liver Disease score in LT candidates, and sCr-based estimated glomerular filtration rate (eGFR) values play an important role in determining medical urgency for LT. However, the use of sCr to assess kidney function may be limited in the cirrhotic milieu due to decreased creatinine production, interference of bilirubin with some laboratory assays for sCr, and expansion of the volume of distribution of creatinine. Therefore, conventional eGFR equations perform poorly in patients with cirrhosis and may overestimate kidney function leading to delayed diagnosis of acute kidney injury or lower priority for LT in patients with a truly low glomerular filtration rate. In this review, we will provide an update on the use of sCr for diagnosis and staging of kidney disease in patients with cirrhosis, discuss the limitations of sCr-based eGFR equations, and discuss novel eGFR equations that have been developed in patients with cirrhosis.

Associations of prematurity and low birth weight with blood pressure and kidney function in middle-aged participants of the Brazilian Longitudinal Study of Adult Health: ELSA-Brasil

BACKGROUND

An adverse intrauterine environment reflected by low birth weight (LBW) and prematurity may induce fetal programming that favors kidney dysfunction in adulthood. We examined the association of LBW and prematurity with blood pressure (BP) and kidney function markers in non-diabetic, middle-aged adults without kidney disease from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

METHODS

A cross-sectional analysis of 768 subjects aged 35-54 years was conducted. Comparisons were performed according to self-reported birth weight: LBW (< 2.5 kg) or normal birth weight (2.5-4.0 kg). Associations of LBW and prematurity with BP levels and kidney function markers "(estimated glomerular filtration rate [eGFR], albumin-creatinine ratio [ACR] and serum cystatin-C) were tested by multiple linear regression using adjustments based on Directed Acyclic Graphs. Propensity score matching was applied to control imbalances.

RESULTS

Mean age of participants was 45.5 ± 4.6 years and 56.8% were female; 64 (8.3%) participants reported LBW and 39 (5.0%) prematurity. The LBW group had higher systolic (p = 0.015) and diastolic BP (p = 0.014) and ACR values (p = 0.031) and lower eGFR (p = 0.015) than the normal birth weight group, but no group difference for cystatin-C was found. The preterm group had higher mean levels of systolic and diastolic BP, but no difference in kidney function markers was evident. In a regression model adjusted for sex, skin color and family history of hypertension, both systolic and diastolic BP levels were associated with LBW, but this association disappeared after adding for prematurity, which remained associated with BP (p = 0.017). Having applied a propensity score matching, LBW was associated with ACR values (p = 0.003), but not with eGFR or BP levels.

CONCLUSION

The study findings of independent associations of prematurity with higher BP levels, and of LBW with markers of kidney function in adulthood, support that early life events may predict risk for hypertension and kidney dysfunction in adulthood. The study design precluded the inferring of causality, and prospective studies are needed to further investigate this hypothesis.

A comprehensive review of acute cardio-renal syndrome: need for novel biomarkers

Cardiorenal syndrome represents a wide-spectrum disorder involving the heart and kidneys as the primary affected organs. India has an increasingly high burden of acute CRS, coinciding with the rise in global statistics. Up to 2022, approximately 46.1% of all cardiorenal patients have been diagnosed with acute CRS in India. Acute CRS involves a sudden deterioration of kidney functionalities, referred to as acute kidney injury (AKI) in acute heart failure patients. The pathophysiology of CRS involves hyperactivation of the sympathetic nervous system (SNS) and the renin-angiotensin-aldosterone system (RAAS) following acute myocardial stress. The pathological phenotype of acute CRS is associated with perturbed inflammatory, cellular, and neurohormonal markers in circulation. These complications increase the risk of mortality in clinically diagnosed acute CRS patients, making it a worldwide healthcare burden. Hence, effective diagnosis and early prevention are crucial to prevent the progression of CRS in AHF patients. Present biomarkers, such as serum creatinine (sCr), cystatin C (CysC), glomerular filtration rate (GFR), blood urea nitrogen (BUN), serum and/or urine neutrophil gelatinase-associated lipocalin (NGAL), B-type natriuretic peptide (BNP), and NT-proBNP, are clinically used to diagnose AKI stages in CRS patients but are limitedly sensitive to the early detection of the pathology. Therefore, the need for protein biomarkers is emerging for early intervention in CRS progression. Here, we summarized the cardio-renal nexus in acute CRS, with an emphasis on the present clinicopathological biomarkers and their limitations. The objective of this review is to highlight the need for novel proteomic biomarkers that will curb the burgeoning concern and direct future research trials.

Hemolysis scavenger proteins and renal function marker in children with sickle cell disease at steady state: A cross-sectional study

Background and Aims

Hemolysis is a fundamental feature of sickle cell disease (SCD) contributing to the vaso-occlusive crisis of patients. The objectives of the study were to assess the link between hemolysis proteins and hematological parameters, and to validate cystatin C (CYS C) as a potent renal marker in diagnoising SCD.

Method

Here, a cross-sectional study carried out at the pediatric SCD clinic of the Komfo Anokye Teaching Hospital comprised 90 SCD children (HbSC, HbSF, and HbSS). ANOVA, t-test, and Spearman's rank correlation analysis were done. Elevated proteins levels were compared to standard values; alpha-1 microglobulin (A1M) (1.8-65 µg/L), CYS C (0.1-4.5 µmol/L), and haemopexin (HPX) (500-1500 µg/mL).

Results

The mean (standard deviation) age of participants was 9.830 (±0.3217) years, and 46% of them were males. From simple descriptive analysis, we observed that all but one patient had their HPX level below the reference range (<500 µg/mL). Here, A1M levels were shown to be within the appropriate reference range for all the patients except few patients. CYS C levels were also all within the required reference values. A Spearman's rank correlation test between full blood count and HPX generally suggested a weak but positive correlation; RBC (coef. = 0.2448; p = 0.0248), HGB (coef. = 0.2310; p = 0.030), hematocrit (coef. = 0.2509; p = 0.020), and platelet (coef. = 0.1545; p = 0.160). Mean corpuscular volume (coef. = -0.5645; p = 0.610) had a stronger but negative correlation with HPX. This study depicts a positive and stronger association between CYS C and HPX levels (coef. = 0.9996; p < 0.0001), validating the use of CYS C as a useful marker of renal function in persons with SCDs.

Conclusion

In the present study, we show that A1M levels were normal for most of the patients, hence CYS C levels are not alarming in this study. Further, there exists a correlation between hemolysis scavenger proteins and hematological parameters.

Recent Developments in the Evaluation and Management of Cardiorenal Syndrome: A Comprehensive Review

Cardiorenal syndrome (CRS) is an increasingly recognized diagnostic entity associated with high morbidity and mortality among acutely ill heart failure (HF) patients with acute and/ or chronic kidney diseases (CKD). While traditionally viewed as a state of decline in glomerular filtration rate (GFR) due to decreased renal perfusion, mainly due to therapeutic interventions to relieve congestive in HF, recent insights into the underlying pathophysiologic mechanisms of CRS led to a broader definition and further classification of CRS into 5 distinct types. In this comprehensive review, we discuss the classification of CRS, highlighting the underlying common pathogenetic pathways of heart failure and kidney injury, including increased congestion, neurohormonal dysregulation, oxidative stress as well as inflammation, and cytokine storm that are particularly evident in COVID-19 patients with multiorgan failure and also in those with other disorders including sepsis, systemic lupus erythematosus and amyloidosis. In this review we also present the recent advances in the diagnostic strategies of CRS including cardiac and renal biomarkers as well as advanced cardiac and renal imaging techniques that are available to aid in the diagnosis as well as in the prognostication of this disorder. Finally, we discuss the various therapeutic options available to-date, including fluid optimization, hemofiltration, renal replacement therapy as well as the role of SGLT2 inhibitors in light of recent data from RCTs. It is important to note that, CRS population are either excluded or underrepresented, at best, in major RCTs and therefore, therapeutic recommendations are largely extrapolated from HF and CKD clinical trials.

Proenkephalin A as a marker for glomerular filtration rate in critically ill children: validation against gold standard iohexol GFR measurements

OBJECTIVES

Accurate determination of glomerular filtration rate (GFR) is important. Several endogenous biomarkers exist for estimating GFR, yet, they have limited accuracy, especially in the paediatric population. Proenkephalin A 119-159 (PENK) is a novel and promising GFR marker, but its relation with age in children remains unknown. Also, the value of PENK has never been validated against measured GFR (mGFR) in children when compared to traditional GFR markers including serum creatinine (SCr), SCr-based estimated GFR (eGFR) and cystatin C (cysC).

METHODS

Critically ill children and term-born neonates were included in this single-centre, prospective study. Iohexol-based mGFR, SCr, and cysC were determined in each patient. eGFR was calculated using the bedside Schwartz equation, incorporating SCr and height. Spearman correlation coefficients were calculated to determine the correlation between mGFR and PENK, SCr, cysC and eGFR.

RESULTS

For 97 patients (56 children and 41 neonates), mGFR, SCr, cysC and PENK levels were available. PENK levels were higher in young children and decreased to adult PENK reference values around two years of age. PENK levels were highly correlated with mGFR (ρ=-0.88, p<0.001), and similar to mGFR-eGFR correlation (ρ=-0.87, p<0.001). For cysC and SCr the correlation with mGFR was lower (ρ=-0.77 and ρ=-0.46, respectively. Both p<0.001).

CONCLUSIONS

The correlation of PENK with mGFR was as good as SCr-based eGFR-mGFR correlation. To determine the added value of PENK in paediatric clinical care and prior to implementation, PENK reference values are needed and the development and validation of a paediatric PENK-based eGFR equation is necessary.

Comparison of 24-hour urinary creatinine clearance and estimated glomerular filtration rate based on a panel of filtration markers in patients with chronic kidney disease

Diagnosis and management of chronic kidney disease (CKD) requires accurate assessment of glomerular filtration rate (GFR). In practice, GFR is typically estimated by equations based on creatinine concentration in blood, but creatinine is affected by non-GFR factors such as age and sex. Alternative filtration markers such as cystatin C, beta-trace protein (BTP), and beta-2 microglobulin (B2M) may be less dependent on age and sex, but equations combining these markers have not been investigated in patients with chronic kidney disease (CKD). In this cross-sectional study of 50 patients with CKD stage 3-4, we compared kidney function estimates based on creatinine, cystatin C, BTP, B2M, or a combination of markers. Compared to the creatinine/cystatin C combination equation, the panel equation yielded a mean difference of only 2.8 ml/min/1.73 m2 , indicating that switching to the panel equation would be unlikely to affect management.

Serum Orotidine: A Novel Biomarker of Increased CVD Risk in Type 2 Diabetes Discovered Through Metabolomics Studies

OBJECTIVE

To identify novel biomarkers of cardiovascular disease (CVD) risk in type 2 diabetes (T2D) via a hypothesis-free global metabolomics study, while taking into account renal function, an important confounder often overlooked in previous metabolomics studies of CVD.

RESEARCH DESIGN AND METHODS

We conducted a global serum metabolomics analysis using the Metabolon platform in a discovery set from the Joslin Kidney Study having a nested case-control design comprising 409 individuals with T2D. Logistic regression was applied to evaluate the association between incident CVD events and each of the 671 metabolites detected by the Metabolon platform, before and after adjustment for renal function and other CVD risk factors. Significant metabolites were followed up with absolute quantification assays in a validation set from the Joslin Heart Study including 599 individuals with T2D with and without clinical evidence of significant coronary heart disease (CHD).

RESULTS

In the discovery set, serum orotidine and 2-piperidinone were significantly associated with increased odds of incident CVD after adjustment for glomerular filtration rate (GFR) (odds ratio [OR] per SD increment 1.94 [95% CI 1.39-2.72], P = 0.0001, and 1.62 [1.26-2.08], P = 0.0001, respectively). Orotidine was also associated with increased odds of CHD in the validation set (OR 1.39 [1.11-1.75]), while 2-piperidinone did not replicate. Furthermore, orotidine, being inversely associated with GFR, mediated 60% of the effects of declining renal function on CVD risk. Addition of orotidine to established clinical predictors improved (P < 0.05) C statistics and discrimination indices for CVD risk (ΔAUC 0.053, rIDI 0.48, NRI 0.42) compared with the clinical predictors alone.

CONCLUSIONS

Through a robust metabolomics approach, with independent validation, we have discovered serum orotidine as a novel biomarker of increased odds of CVD in T2D, independent of renal function. Additionally, orotidine may be a biological mediator of the increased CVD risk associated with poor kidney function and may help improve CVD risk prediction in T2D.

Higher cystatin C level increases the risk of delayed cerebral ischemia after endovascular treatment of aneurysmal subarachnoid hemorrhage: a case-control study

Cystatin C (CysC) has been found to be associated with hemorrhagic and ischemic stroke in many studies. However, the association between CysC level and the risk of delayed cerebral ischemia after endovascular treatment of aneurysmal subarachnoid hemorrhage has been reported rarely. Our study was proposed to explore this association. Consecutive patients from June 2015 to February 2021 in this single-center retrospective study were selected. Univariate and multivariate analyses were used to identify potential prognostic risk factors for delayed cerebral ischemia, and the stability of the association was demonstrated by several statistical methods, such as subgroup analysis, interaction testing, generalized linear models, and propensity score matching. A total of 424 patients were included in the analysis. Cystatin C was independently associated with delayed cerebral ischemia. The independent effects of CysC on delayed cerebral ischemia were shown in generalized linear models with a logit link, and the results were relatively stable in crude, partial, and full models with ORs (95% CIs) for delayed cerebral ischemia. Subgroup analysis showed no significant subgroup differences in the effect of CysC on delayed cerebral ischemia. There was also no interaction effect between CysC and other confounders. Patients in the high CysC group had a higher risk of delayed cerebral ischemia than those in the low CysC group before and after propensity score matching. CysC level could be an independent predictor for the risk of delayed cerebral ischemia after endovascular treatment of aneurysmal subarachnoid hemorrhage.

Urinary cystatin C: pediatric reference intervals and comparative assessment as a biomarker of renal injury among children in the regions with high burden of CKDu in Sri Lanka

BACKGROUND

Cystatin C (Cys-C) is an emerging biomarker of renal diseases and its clinical use, particularly for screening the communities affected by chronic kidney disease of unknown etiology (CKDu), is hindered due to the lack of reference intervals (RIs) for diverse ethnic and age groups. The present study aimed to define RIs for urinary Cys-C (uCys-C) for a healthy pediatric population in Sri Lanka and in turn compare the renal function of the residential children in CKDu endemic and non-endemic regions in Sri Lanka.

METHODS

A cross-sectional study was conducted with 850 healthy children (10-17 years) from selected locations for reference interval establishment, while a total of 892 children were recruited for the comparative study. Urine samples were collected and analyzed for Cys-C, creatinine (Cr) and albumin. Cr-adjusted uCys-C levels were partitioned by age, and RIs were determined with quantile regression (2.5th, 50th and 97.5th quantiles) at 90% confidence interval.

RESULTS

The range of median RIs for uCys-C in healthy children was 45.94-64.44 ng/mg Cr for boys and 53.58-69.97 ng/mg Cr for girls. The median (interquartile range) uCys-C levels of children in the CKDu endemic and non-endemic regions were 58.18 (21.8-141.9) and 58.31 (23.9-155.3) ng/mg Cr with no significant difference (P = 0.781). A significant variation of uCys-C was noted in the children across age.

CONCLUSIONS

Notably high uCys-C levels were observed in children with elevated proteinuria. Thus, uCys-C could be a potential biomarker in identifying communities at high risk of CKDu susceptibility.

Biomarkers of acute kidney injury in pediatric cardiac surgery

Acute kidney injury (AKI) is characterized by a sudden decrease in kidney function. Children with congenital heart disease are a special group at risk of developing AKI. We performed a systematic review of the literature to search for studies reporting the usefulness of novel urine, serum, and plasma biomarkers in the diagnosis and progression of AKI and their association with clinical outcomes in children undergoing pediatric cardiac surgery. In thirty studies, we analyzed the capacity to predict AKI and poor outcomes of five biomarkers: Cystatin C, Neutrophil gelatinase-associated lipocalin, Interleukin-18, Kidney injury molecule-1, and Liver fatty acid-binding protein. In conclusion, we suggest the need for further meta-analyses with the availability of additional studies.

OUP accepted manuscript

Background

Methods

Results

Conclusions

The Effect of Mild Renal Dysfunction on the Assessment of Plasma Amino Acid Concentration and Insulin Resistance in Patients with Type 2 Diabetes Mellitus

BACKGROUND

An increase in the levels of branched-chain amino acids (BCAAs) and certain aromatic amino acids, such as alanine, in plasma is correlated with insulin resistance (IR) in type 2 diabetes mellitus (T2DM). T2DM is a leading risk factor for chronic kidney disease. Meanwhile, renal dysfunction causes changes in plasma amino acid levels. To date, no study has examined how mild renal dysfunction and IR interact with plasma amino acid levels. This study examines the effects of IR and renal dysfunction on plasma amino acid concentrations in T2DM.

METHODS

Data were collected from healthy male participants (controls) and male patients with T2DM between May 2018 and February 2022. Blood samples were collected after overnight fasting. IR and renal function were evaluated using the homeostasis model assessment of IR (HOMA-IR) and serum cystatin C (CysC), respectively.

RESULTS

A total of 49 and 93 participants were included in the control and T2DM groups, respectively. In the T2DM group, eight amino acids (alanine, glutamic acid, glutamine, glycine, isoleucine, leucine, tyrosine, and valine) and total BCAA showed a significant correlation with HOMA-IR (p < 0.01), whereas six amino acids (γ-aminobutyric acid, citrulline, cysteine, glycine, methionine, and valine) and total BCAA showed a significant correlation with 1/CysC (p < 0.02). However, only alanine, glutamic acid, and each BCAA showed significant differences between the control group and the IR T2DM subgroup. Increases in the BCAA levels with T2DM were canceled by renal dysfunction (CysC ≥ 0.93) in patients with intermediate IR.

CONCLUSION

To use plasma BCAA concentration as a marker of IR, renal function must be considered, even in mild renal dysfunction. Increased alanine and glutamic acid levels indicate IR, regardless of mild renal dysfunction.

Association Between Serum Cystatin C and Thyroid Diseases: A Systematic Review and Meta-Analysis

Background

Cystatin C (CysC) is often used to diagnose and monitor renal diseases. Although some studies have investigated the association between serum CysC levels and thyroid diseases, their reported results were inconsistent. Therefore, the relationship between CysC levels and thyroid diseases remains controversial.

Aim

This meta-analysis aimed to statistically evaluate serum CysC levels in patients with thyroid diseases.

Methods

A literature search was conducted using the PubMed, Web of Science, Embase, EBSCO, and Wiley Online Library databases. The following search terms were used for the title or abstract: "Cystatin C" or "CysC" in combination with the terms "thyroid disease", "thyroid function", "hypothyroidism", or "hyperthyroidism". The results of the systematic analysis were presented as standardized mean differences (SMDs) with corresponding 95% confidence intervals (CIs).

Results

Eleven articles (1,265 cases and 894 controls) were included in the meta-analysis. The results of the meta-analysis showed that the serum CysC levels of patients with hyperthyroidism were significantly higher than those of the controls (SMD: 1.79, 95% CI [1.34, 2.25]), and the serum CysC levels of patients with hypothyroidism were significantly lower than those of the controls (SMD -0.59, 95% CI [-0.82, -0.36]). Moreover, the treatment of thyroid diseases significantly affected serum CysC levels.

Conclusions

To the best of our knowledge, this meta-analysis is the first to evaluate serum CysC levels in patients with thyroid diseases. Our findings suggest that thyroid function affects serum CysC levels and that serum CysC may be an effective marker for monitoring thyroid diseases.

Systematic Review Registration

PROSPERO [https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=258022], identifier CRD42021258022].

Rat Model Investigation on the Role of Biomarkers in Hepatic Ischemia-Reperfusion Injury

OBJECTIVES

Liver function is affected by ischemiareperfusion. Ischemia-reperfusion injury to the liver often follows hepatobiliary surgery. Here, we investigated biomarkers of liver ischemia-reperfusion injury using an animal model.

MATERIALS AND METHODS

For this study, 24 male Sprague Dawley rats (146-188 g) were divided into 4 groups: group A was the control group, group B was the partial hepatic ischemia-reperfusion group, group C was the total hepatic ischemia-reperfusion group, and group D was the intermittent total hepatic ischemiareperfusion group. Laboratory liver function levels were measured before ischemia, after ischemia, and after reperfusion. We used liver and renal biopsies for histopathological examination at the end of the study.

RESULTS

After clamping and reperfusion, alanine aminotransferase and cystatin C levels in groups B, C, and D were significantly higher than levels in group A. In group B, after clamping, neutrophil gelatinaseassociated lipocalin levels were higher than in groups A and D, with significantly higher level than in group D after reperfusion. Neutrophil gelatinase-associated lipocalin levels decreased significantly in groups B, C, and D after reperfusion. There was significantly greater hepatic damage in groups B, C, and D compared with group A but no significant differences in renal injury scores among the groups. There was a significant positive correlation between hepatic damage and renal injury. With regard to histopathological examination versus laboratory results, a statistically significant positive correlation was shown between grade of hepatic damage and serum alanine aminotransferase and cystatin C levels. Similarly, there was a positive correlation between renal damage score and alanine aminotransferase level.

CONCLUSIONS

In our animal model, alanine amino - transferase and cystatin C levels tended to increase with ischemia-reperfusion injury levels but neutrophil gelatinase-associated lipocalin decreased during reperfusion. In liver ischemia, we suggest that neutrophil gelatinase-associated lipocalin may be an important biomarker for distinguishing the reperfusion phase.

Superiority of Cystatin C over Creatinine for Early Diagnosis of Acute Kidney Injury in Pediatric Acute Lymphoblastic Leukemia/Lymphoblastic Lymphoma

The exact incidence of acute kidney injury (AKI) during chemotherapy for acute lymphoblastic leukemia (ALL)/lymphoblastic lymphoma (LBL) is unknown. Furthermore, childhood cancer survivors are at risk of AKI-chronic kidney disease transition. Thus, early diagnosis of AKI is crucial. This study aimed to elucidate the incidence of AKI in patients undergoing chemotherapy for pediatric ALL/LBL and to compare the usefulness of serum cystatin C (CysC)- and creatinine (Cr)-based estimated glomerular filtration rate (eGFR) as diagnostic measures. Data of 16 patients with ALL/LBL treated with a total of 75 courses of chemotherapy were retrospectively analyzed. CysC- and Cr-based eGFR were measured before and three times per week during therapy. To calculate the eGFR, an equation for Japanese children was used. AKI was diagnosed when eGFR dropped by ≥ 25% from the highest eGFR value obtained during the latest 2 weeks since the start of chemotherapy. AKI was graded based on the pediatric Risk, Injury, Failure, Loss, End Stage Renal Disease scale. All patients developed AKI during chemotherapy; however, more than 90% of the cases were mild and eventually recovered. No significant differences were found in the incidence of AKI between CysC- and Cr-based eGFR (p = 0.104). The median time to AKI diagnosis was significantly shorter in the CysC-based eGFR than in the Cr-based eGFR (8 vs. 17 days, p < 0.001). In this study, all patients with pediatric ALL/LBL could develop mild AKI during treatment. CysC-based eGFR is a more effective measure than Cr-based eGFR for the early diagnosis of AKI.

The role of cystatin C, neutrophil-lymphocyte ratio and platelet-lymphocyte ratio in the evaluation of kidney function in women with preeclampsia

OBJECTIVE

We aimed to compare the diagnostic efficiency of cystatin C with traditional kidney markers in preeclampsia and to evaluate the relationship of these markers with neutrophil-lymphocyte and thrombocyte-lymphocyte ratios.

MATERIALS AND METHODS

14 severe preeclampsia, 48 mild preeclampsia and 79 patients with healthy pregnancy who presented to our obstetrics and gynecology clinic within one year were compared. These three groups were compared in terms of demographic characteristics, physical findings, serum urea, creatinine, cystatin C levels, and neutrophil-lymphocyte and platelet-lymphocyte ratios.

RESULTS

The mean serum cystatin C, creatinine and uric acid levels were higher in the severe preeclampsia group compared with the mild preeclamptic and healthy pregnancies (p < 0.001). While cystatin C values increased as the week of gestation increased in the mild preeclampsia group, there was no relation with the gestational week in the control group and the severe preeclampsia group. However, the highest cystatin C values were in the severe preeclampsia group, regardless of the week (p < 0.05). The area under the ROC curve was statistically significant for cystatin C, uric acid and creatinine, but of these three values, cystatin C had the highest sensitivity and specificity. Neutrophil-lymphocyte ratio (NLR) was significantly higher in the severe preeclampsia group than healthy pregnancies, but the level was not significant compared to mild preeclampsia. There was no difference between the groups in terms of platelet-lymphocyte ratio.

CONCLUSION

It can be suggested that cystatin C level reflects renal functions better than uric acid and creatinine in preeclampsia. Cystatin C can be used as a prognostic marker in preeclamptic pregnancies, and rising levels may be valuable for predicting severe preeclampsia. Especially with advancing gestational week, the increase in cystatin C level may indicate an association with the development of preeclampsia. NLR levels may be a parameter correlating with severity in severe preeclampsia.

Role of biomarkers of cardiac remodeling, myofibrosis, and inflammation in assessment of disease severity in euvolemic patients with chronic stable heart failure

OBJECTIVE

This study aimed to determine the importance of biomarkers of chronic heart failure (CHF) for assessing disease severity in euvolemic stable patients.

PATIENTS AND METHODS

N-terminal pro-B-type natriuretic peptide (NT-proBNP), growth differentiation factor (GDF)-15, galectin-3, cystatin-C, soluble suppression of tumorigenicity 2 (sST2), tissue type inhibitor of matrix metalloproteinase (TIMP)-1, and ceruloplasmin levels were measured in euvolemic patients with stable CHF. Severity of CHF was defined by echocardiographic and biochemical parameters.

RESULTS

In 160 patients (123 men and 37 women, mean age: 65.8±12.2 years), we found strong associations between NT-proBNP and bilirubin levels (r = 0.434) and the estimated glomerular filtration rate (r = -0.321). GDF-15 and cystatin-C levels were significantly correlated with parameters of kidney function. In multivariable regression analysis, NT-proBNP levels were associated with the left ventricular ejection fraction and left ventricular end-systolic volume (coefficient of determination R² = 0.777). Additionally, GDF-15 levels were correlated with urea levels (R² = 0.742), and cystatin C levels were correlated with urea and bilirubin levels (R² = 0.732).

CONCLUSION

Besides NT-proBNP, GDF-15 and cystatin C are promising biomarkers for establishing the severity of disease in euvolemic patients with stable CHF.

Factors contributing to discrepant estimated glomerular filtration values measured by creatinine and cystatin C in patients with rheumatoid arthritis

This study aimed to clarify the factors underlying the discrepancy that has been noted between estimated glomerular filtration ratio (eGFR) measured using serum creatinine (Cr) and eGFR using serum cystatin C (CysC) in patients with rheumatoid arthritis (RA) and to identify those patients whose renal function should be evaluated using CysC. We retrospectively evaluated clinical features, disease activity, Steinbrocker radiological staging, and co-morbidities (diabetes mellitus, hypertension, dyslipidemia) in 238 RA patients. eGFR using serum creatinine (eGFR-Cr) and eGFR using serum cystatin C (eGFR-CysC) were calculated using the new Japanese coefficient-modified Modification of Diet in Renal Disease study equation. To clarify the cause(s) of differences of 20% or more between the two eGFRs, we divided our RA patients into Group A (eGFR-Cr/eGFR-CysC ≥ 1.2) and Group B (eGFR-Cr/eGFR-CysC < 1.2), and searched for factors independently related to Group A. Forty-five patients (18.9%) were assigned to Group A, and 193 (81.1%) to Group B. BMI (Odds Ratio [OR] 0.820, 95% confidence interval [CI] 0.675–0.996), Hb (OR 0.633, 95% CI 0.433–0.926), CK (OR 0.773 per 10 units, 95% CI 0.644–0.933), NSAID use (OR 0.099, 95% CI 0.020–0.494), diabetes mellitus (OR 6.024, 95% CI 1.508–24.390) and stage 4 Steinbrocker radiological stage (OR 10.309, 95% CI 2.994–35.714) were identified as independent relevant factors for Group A by a multifactorial analysis. Renal function in RA patients with low BMI, diabetes, anemia and low CK may be overestimated using eGFR-Cr alone, and such patients need to be evaluated using eGFR-CysC.

Is trimethoprim/sulfamethoxazole-associated increase in serum creatinine a pseudo-elevation or true nephrotoxicity?

INTRODUCTION

The aim of this study was to determine the rates of trimethoprim/sulfamethoxazole (TMP/SMX)-associated pseudo-elevation and true nephrotoxicity by comparison of creatinine-estimated and cystatin C-estimated GFRs (glomerular filtration rates) before and after TMP/SMX administrations.

METHODS

Patients in whom serum creatinine and cystatin C were simultaneously measured are the cohort of this study. A decreasing of creatinine-estimated GFR posterior to TMP/SMX by ≥ 20% and a decreasing of cystatine C-estimated GFR posterior to TMP/SMX by ≥ 20% were defined as true nephrotoxicity. A decreasing of creatinine-estimated GFR posterior to TMP/SMX by ≥ 20% and a decreasing of cystatine C-estimated GFR posterior to TMP/SMX by < 20% were defined as pseudo-elevation.

RESULTS

A total of 66 patients were enrolled. Within the 19 patients in whom serum creatinine and cystatin C were measured simultaneously both before and after TMP/SMX administrations, 10 patients (52.6%) had nephrotoxicity. Fewer random error and systematic bias between creatinine- and cystatine C-estimated GFR were observed after TMP/SMX than before TMP/SMX by Bland-Altman analysis.

CONCLUSIONS

Using cystatin C, we reveled TMP/SMX-associated nephrotoxicity is not uncommon. We should equally pay attention to TMP/SMX-associated nephrotoxicity and pseudo-elevation. In spite of pseudo-elevation, creatinine-estimated GFR after receiving TMP/SMX is ironically reliable as surrogate maker for renal clearance.

Acute kidney damage by PM2.5 exposure in a rat model

PM2.5 exposure is associated with a glomerular filtration rate (GFR) reduction, and renal tissue damage. The goal of this study was demonstrate the acute effect of PM2.5 on the kidney. Male rats were acutely exposed to PM2.5 or filtered air. Blood pressure was mesure and early kidney biomarkers were evaluated in serum and urine samples, and also IL-1β, IL-6 and TNFα were determined. Oxidative biomarkers, angiotensin/bradykinin-related proteins, KIM-1, IL-6 and histology were determined. Blood pressure, GFR, and early kidney damage biomarkers increase together with oxidative biomarkers and angiotensin/bradykinin endocrine-related proteins increased after exposure to PM2.5. Urinary IL-6 increased after exposure to PM2.5, whereas in kidney cortex decreased. Histological changes were observed and accompanied by the induction of KIM-1. Acute exposure to PM2.5 not decline kidney function. However, it can induce early kidney damage biomarkers, oxidative stress, inflammation and angiotensin mediators, which perhabs culminates in a lose of renal function.

Week 96 subgroup analyses of the phase 3, randomized AMBER and EMERALD trials evaluating the efficacy and safety of the once daily darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) single-tablet regimen in antiretroviral treatment (ART)-naïve and -experienced, virologically-suppressed adults living with HIV-1

BACKGROUND

Darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) 800/150/200/10 mg was investigated in AMBER (treatment-naïve adults; NCT02431247) and EMERALD (treatment-experienced, virologically-suppressed adults; NCT02269917).

OBJECTIVE

To describe a Week 96 pre-planned subgroup analysis of D/C/F/TAF arms by demographic characteristics (age ≤/>50 years, gender, black/non-black race), and baseline clinical characteristics (AMBER: viral load [VL], CD4⁺ count, WHO clinical stage, HIV-1 subtype and antiretroviral resistance; EMERALD: prior virologic failure [VF], antiretroviral experience, screening boosted protease inhibitor [PI], and boosting agent).

METHODS

Patients in D/C/F/TAF and control arms could continue on/switch to D/C/F/TAF in a single-arm, open-label extension phase after Week 48 until Week 96. Efficacy endpoints were percentage cumulative confirmed VL ≥50 copies/mL (virologic rebound; EMERALD), and VL <50 (virologic response), or ≥50 copies/mL (VF) (FDA snapshot; both trials).

RESULTS

D/C/F/TAF demonstrated high Week 96 virologic responses (AMBER: 85% [308/362]; EMERALD: 91% [692/763]) and low VF rates (AMBER: 6% [20/362]; EMERALD: 1% [9/763]). In EMERALD, D/C/F/TAF showed low virologic rebound cumulative through Week 96 (3% [24/763]). Results were consistent across subgroups, including prior antiretroviral experience in EMERALD. No darunavir, primary PI, or tenofovir resistance-associated mutations were observed post-baseline. Study-drug-related serious adverse events (AEs) and AE-related discontinuations were <1% and 2%, respectively (both D/C/F/TAF arms), and similar across subgroups. eGFR_cyst and bone mineral density improved or were stable and lipids increased through Week 96 across demographic subgroups, with small changes in total-cholesterol/HDL-cholesterol ratio.

CONCLUSIONS

D/C/F/TAF was effective with a high barrier to resistance and bone/renal safety benefits, regardless of demographic or clinical characteristics for treatment-naïve and treatment-experienced, virologically-suppressed adults.

The effect of six months aerobic exercise during dialysis on liver enzymes, cystatin C and quality of life of hemodialysis patients

BACKGROUND

The purpose of this study was to investigate the effect of six-month aerobic exercise during dialysis on hepatic enzymes, cystatin c, glomerular filtration factors and the quality of life of hemodialysis patients.

METHODS

The subjects of this study were 30 subjects randomly divided into two groups including experimental groups (N.=15) and control (N.=15). The aerobic exercise program consisted of six months of aerobic exercise, 3 sessions per week, and each session for 30 to 45 minutes with a maximum intensity of 50-70% of the maximum heart rate stored on the minibike. Paired sample t-test and repeated measures (ANOVA) were used to compare between- and within-group variance changes. Significance level was considered less than 0.05.

RESULTS

Mass loss, Body Mass Index, body fat percentage, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, cystatin C significantly decreased while the maximum oxygen consumption at the end of the period increased significantly. Changes in intragroup mean in physical, psychological, general health, vitality, social activity, physical function, emotional function, and life satisfaction in the group of men with kidney disease increased significantly at the end of the training period. Phosphorus, calcium, sodium, potassium, urea, creatinine and bilirubin levels decreased significantly.

CONCLUSIONS

The results indicate the positive effects of using aerobic exercise as a noninvasive and non-pharmacological method with minimal side effects that can be effective in improving the renal function of these patients. Therefore, due to this, this method can probably be used to improve the condition of patients under hemodialysis.

Prognostic role of plasma galectin-3 levels in acute coronary syndrome

Aim:

Cystatin C, neutrophil gelatinase-associated lipocalin and galectin-3 have emerged as biomarker candidates to predict cardiovascular outcomes and mortality in the general population as well as in patients with coronary artery or renal disease. However, their predictive role and clinical utility in patients with acute coronary syndromes alone or in combination beyond currently used risk scores remains to be determined.

Methods and results:

Cystatin C, neutrophil gelatinase-associated lipocalin, and galectin-3 were measured in plasmas of 1832 patients at the time of presentation with acute coronary syndromes requiring percutaneous coronary intervention or coronary artery bypass grafting. The primary outcomes were major adverse cardiac and cerebrovascular events (defined as the composite of all-cause mortality, cerebrovascular events, any repeat revascularization or myocardial infarction) and all-cause mortality after 1 year and occurred in 192 (10.5%) and 78 (4.3%) of patients, respectively. All three biomarkers were increased in those with major adverse cardiac and cerebrovascular events compared with those without (p&lt;0.001). However, only galectin-3 (all-cause mortality: hazard ratio=1.027 (95% confidence interval (1.011–1.043); p=0.001), major adverse cardiac and cerebrovascular events: hazard ratio=1.025 (95% confidence interval (1.012–1.037); p&lt;0.001)) but not cystatin C nor neutrophil gelatinase-associated lipocalin emerged as independent predictors of both major adverse cardiac and cerebrovascular events and death. The risks were particularly high in the highest quartile of galectin-3. The integration of galectin-3 into the global registry of acute coronary events (GRACE) score improved the prediction of major adverse cardiac and cerebrovascular events and all-cause mortality significantly. The areas under the receiver operator characteristics curves increased from 0.6701 to 0.6932 for major adverse cardiac and cerebrovascular events (p=0.0474) and from 0.804 to 0.8199 for all-cause mortality (p=0.0197). Finally, we applied net reclassification improvement index using different cut-offs for major adverse cardiac and cerebrovascular events which showed negative results (for the cut-offs of 5% and 15%, net reclassification improvement index 0.028, p=0.586, for the cut-offs of 10% and 20%, net reclassification improvement index 0.072, p=0.1132 and for the cut-offs of 10% and 30% the net reclassification improvement index is 0.0843, p=0.077).

Conclusion:

In acute coronary syndromes patients, galectin-3 has moderate prognostic accuracy, provides statistically significant incremental value in some, but not all models, and that the magnitude of any improvement would seem of questionable clinical value.

Relationship between serum cystatin C and prognosis of nondiabetic peritoneal dialysis patients

We investigated whether serum cystatin C predicted treatment failure and mortality in nondiabetic peritoneal dialysis (PD) patients. We studied 163 new-onset, nondiabetic PD patients between January 2010 and January 2019. Patients were followed up until death or 1 July 2019. Serum cystatin C was measured within 1 week before PD. Basic demographic and laboratory test data were collected. Patients were divided into low (<5.54 mg/L) and high (≥5.54 mg/L) serum cystatin C groups. The Kaplan-Meier method and log-rank test showed that the technical survival rate of the low cystatin C group was higher than that of the high cystatin C group. There was no difference in overall survival between the two groups. Multivariate Cox model showed that serum cystatin C was an independent risk factor for PD failure. Serum cystatin C could predict PD failure but was not associated with mortality in nondiabetic PD patients.

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.

Formulas Estimating Glomerular Filtration Rate in the Evaluation of Living Kidney Donor Candidates: Comparison of Different Formulas With Scintigraphy-Measured Glomerular Filtration Rate

INTRODUCTION

Estimation of kidney function is crucial in the evaluation of living kidney donor candidates. Despite the multitude of glomerular filtration rate (GFR) formulas, no equation is universal, and none were validated in the population of kidney donors. Novel biomarkers, including beta trace protein (BTP) and cystatin C, are studied to help estimate GFR and improve the safe qualification of living kidney donors.

AIM

This study compares the accuracy of different formulas that estimate GFR with reference scintigraphy-measured GFR in the population of living kidney donor candidates.

MATERIAL AND METHODS

This study enrolled 30 healthy living kidney donor candidates. GFR was measured using the following 11 different formulas. For reference, GFR was assessed using 99m-Technetium-diethylenetriaminepentaacetic acid.

RESULTS

The accuracy of estimation was generally low in all formulas. The strongest correlation between measured GFR (mGFR) and estimated GFR (eGFR) was achieved by the Nankivell formula (R = 0.47, P = .009); however, in the group of patients with a body mass index of >25 kg/m², only the equations based on BTP had a statistically significant correlation with mGFR: White (R = 0.59; P = .016) and Poge (R = 0.53; P = .035). Bland-Altman plots revealed wide limits of agreement between eGFRs and mGFR in all groups of patients.

CONCLUSION

In living kidney donor candidates, GFR estimation formulas should be chosen individually. White formula, which is based on BTP, may be a promising tool in estimating GFR in overweight potential living kidney donor candidates. More than 1 formula and personalized choice of GFR estimation method regarding the given patient should be performed in qualification of kidney donors.

Biomarkers to predict the response to cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is an established non-pharmacological treatment for selected heart failure patients with wide QRS duration. However, there is a persistent number of non-responders throughout. The prediction of the CRT response is paramount to adequately select the correct patients for CRT. One of the expanding fields of research is the development of biomarkers that predict the response to CRT. A review of the available literature on biomarkers in CRT patients has been performed to formulate a critical appraisal of the available data. The main conclusion of our review is that biomarker research in this patient population is very fragmented and broad. This results in the use of non-uniform endpoints to define the CRT response, which precludes an in-depth comparison of the available data. To improve research development in this field, a uniform definition of the CRT response and relevant endpoints is necessary to better predict the CRT response.

Association of Different Estimates of Renal Function With Cardiovascular Mortality and Bleeding in Atrial Fibrillation

Background

We compared different methods of estimated glomerular filtration rate (eGFR) and their association with cardiovascular death and major bleeding in 14 980 patients with atrial fibrillation in the ARISTOTLE (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation) trial.

Methods and Results

eGFR was calculated using equations based on creatinine (Cockcroft‐Gault, Modification of Diet in Renal Disease, and Chronic Kidney Disease Epidemiology Collaboration [CKD‐EPI]) and/or cystatin C (CKD‐EPI_CysC and CKD‐EPI_{CysC+Creatinine}). These 5 eGFR equations, as well as the individual variables that are used in these equations, were assessed for correlation and discriminatory ability for cardiovascular death and major bleeding. The median age was 70.0 years, and 35.6% were women. The median eGFR was highest with Cockcroft‐Gault (74.1 mL/min) and CKD‐EPI_CysC (74.2 mL/min), and lowest with Modification of Diet in Renal Disease (66.5 mL/min). Correlation between methods ranged from 0.49 (Cockroft‐Gault and CKD‐EPI_CysC) to 0.99 (Modification of Diet in Renal Disease and CKD‐EPI). Among the eGFR equations, those based on cystatin C yielded the highest C indices for cardiovascular death and major bleeding: 0.628 (CKD‐EPI_CysC) and 0.612 (CKD‐EPI_{CysC+Creatinine}), respectively. A model based on the variables within the different eGFR equations (age, sex, weight, creatinine, and cystatin C) yielded the highest discriminatory value for both outcomes, with a C index of 0.673 and 0.656, respectively.

Conclusions

In patients with atrial fibrillation on anticoagulation, correlation between eGFR calculated using different methods varied substantially. Cystatin C–based eGFRs seem to provide the most robust information for predicting death and bleeding. A model based on the individual variables within the eGFR equations, however, provided the highest discriminatory value. Our findings may help refine risk stratification in patients with atrial fibrillation and define how renal function should be determined in future atrial fibrillation studies.

Registration

URL: https://www.clini​caltr​ials.gov; Unique identifier: NCT00412984.

Cystatin C, a Controversial Biomarker in Hypothyroid Patients under Levothyroxine Therapy: THYRenal, a Pilot Cohort Observational Study

BACKGROUND

Cystatin C (Cys-C) is recognized as one of the most reliable renal function parameters in the general population, although it might be biased by thyroid status. Herein, we tested Cys-C and conventional renal parameters in a cohort of hypothyroid patients treated with Levothyroxine.

METHODS

Eighty-four hypothyroid patients were recruited and subgrouped according to their serum thyroid-stimulating hormone (TSH) values as a paradigm for therapeutic targeting (n = 54, optimal TSH range = 0.5-2 µIU/mL; n = 30, TSH > 2µIU/mL). Serum Cys-C, creatinine, measured and estimated glomerular filtration rates (mGFR and eGFR) were assessed. Results-mGFR and eGFR were comparable among the two subgroups, whereas Cys-C was significantly higher in patients with suboptimal TSH values (>2 µIU/mL) (p < 0.0001). TSH significantly correlated with Cys-C in the overall patient group, and in the subgroup with TSH above the target value (>2 µIU/mL). Out of 20 patients with abnormal Cys-C, 19 had suboptimal TSH levels. Receiver operating characteristic (ROC) analysis indicated Cys-C as a moderately accurate diagnostic tool (AUC = 0.871) to assess Levothyroxine replacement efficacy in hypothyroid patients (63% sensitivity, and 98% specificity).

CONCLUSIONS

The observation of increased serum Cys-C in patients with suboptimal TSH would suggest the importance of a careful interpretation by clinicians of this biomarker in the case of hypothyroid patients.

Comprehensive Characterization of the Vascular Effects of Cisplatin-Based Chemotherapy in Patients With Testicular Cancer

Background

Cisplatin-based chemotherapy increases the risk of cardiovascular and renal disease.

Objectives

We aimed to define the time course, pathophysiology, and approaches to prevent cardiovascular disease associated with cisplatin-based chemotherapy.

Methods

Two cohorts of patients with a history of testicular cancer (n = 53) were recruited. Cohort 1 consisted of 27 men undergoing treatment with: 1) surveillance; 2) 1 to 2 cycles of bleomycin, etoposide, and cisplatin (BEP) chemotherapy (low-intensity cisplatin); or 3) 3 to 4 cycles of BEP (high-intensity cisplatin). Endothelial function (percentage flow-mediated dilatation) and cardiovascular biomarkers were assessed at 6 visits over 9 months. Cohort 2 consisted of 26 men previously treated 1 to 7 years ago with surveillance or 3 to 4 cycles BEP. Vasomotor and fibrinolytic responses to bradykinin, acetylcholine, and sodium nitroprusside were evaluated using forearm venous occlusion plethysmography.

Results

In cohort 1, the percentage flow-mediated dilatation decreased 24 h after the first cisplatin dose in patients managed with 3 to 4 cycles BEP (10.9 ± 0.9 vs. 16.7 ± 1.6; p < 0.01) but was unchanged from baseline thereafter. Six weeks after starting 3 to 4 cycles BEP, there were increased serum cholesterol levels (7.2 ± 0.5 mmol/l vs. 5.5 ± 0.2 mmol/l; p = 0.01), hemoglobin A1c (41.8 ± 2.0 mmol/l vs. 35.5 ± 1.2 mmol/l; p < 0.001), von Willebrand factor antigen (62.4 ± 5.4 mmol/l vs. 45.2 ± 2.8 mmol/l; p = 0.048) and cystatin C (0.91 ± 0.07 mmol/l vs. 0.65 ± 0.09 mmol/l; p < 0.01). In cohort 2, intra-arterial bradykinin, acetylcholine, and sodium nitroprusside caused dose-dependent vasodilation (p < 0.0001). Vasomotor responses, endogenous fibrinolytic factor release, and cardiovascular biomarkers were not different in patients managed with 3 to 4 cycles of BEP versus surveillance.

Conclusions

Cisplatin-based chemotherapy induces acute and transient endothelial dysfunction, dyslipidemia, hyperglycemia, and nephrotoxicity in the early phases of treatment. Cardiovascular and renal protective strategies should target the early perichemotherapy period. (Clinical Characterisation of the Vascular Effects of Cis-platinum Based Chemotherapy in Patients With Testicular Cancer [VECTOR], NCT03557177; Intermediate and Long Term Vascular Effects of Cisplatin in Patients With Testicular Cancer [INTELLECT], NCT03557164)

Clinical Accuracy of Average Creatinine and Cystatin-C-Based Estimated GFR in Japanese Living Renal Transplantation Donors

OBJECTIVE

To evaluate the clinical accuracy of several estimated glomerular filtration rates (eGFR) using cystatin-C to measure renal function in Japanese renal donors.

METHODS

In total, 61 healthy, potential renal donors were assessed. The average age was 42.7 years (range: 27-67). We evaluated the GFR based on the 24-hour creatinine clearance (Ccr) using 24-hour urine collection, eGFR based on serum creatinine (eGFRcr), and cystatin-C (eGFRcys) levels using an equation developed by the Japanese Society of Nephrology, the average of the eGFRcr and eGFRcys (eGFRave) rates, and an eGFR based on a combination of serum creatinine and cystatin-C values using an equation developed by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI). The association between Ccr and each eGFR was evaluated using Pearson's r and the Bland-Altman plot.

RESULTS

Pearson's correlation coefficient analysis revealed a significant correlation between the Ccr and the eGFRcr (r = 0.62, P < .0001), eGFRave (r = 45, P = .0003), and eGFRcr-cys (r = 0.451, P = .0014). The Bland-Altman study suggested that each eGFR had a low level of agreement with the Ccr because the latter was higher than each eGFR. On the other hand, the eGFRave had the highest level of agreement with CCr × 0.715.

CONCLUSIONS

The eGFRave may provide a simple and useful method of evaluating renal function in living renal transplant donors.

Remote Ischemic Preconditioning Reduces the Risk of Contrast-Induced Nephropathy in Patients with Moderate Renal Impairment Undergoing Percutaneous Coronary Angiography: A Meta-Analysis

BACKGROUND/AIMS

This meta-analysis evaluated the effects of remote ischemic preconditioning (RIPC) on the risk of contrast-induced nephropathy (CIN) in patients undergoing percutaneous coronary intervention/coronary angiography (PCI/CA).

METHODS

PubMed, Embase, and the Cochrane Central Register of Controlled Trials databases were searched for randomized controlled trials (RCTs) that assessed the effect of RIPC on CIN in patients undergoing PCI/CA. The main outcomes of interest were the incidence of CIN 48-72 h after CA, the levels of serum creatinine, cystatin C, neutrophil gelatinase-associated lipocalin, and estimated glomerular filtration rate (eGFR), mortality, and requirement of hemodialysis and rehospitalization. The analysis was conducted using the random-effect model due to the expected heterogeneity among different studies.

RESULTS

In total, 16 trials covering 2,048 patients were identified. By assessing the methodological quality of the included studies through the Coch-rane risk of bias, we found that of the 16 RCTs, 3 had a low risk of bias, 6 a high, and 7 an unclear risk. The application of RIPC decreased the incidence of CIN (relative risk, RR, 0.50, 95% confidence interval, CI, 0.39-0.65; p < 0.001). Subgroup analyses showed that RIPC decreased the incidence of CIN in patients with eGFR <60 mL/min/1.73 m2 (RR 0.53, 95% CI 0.38-0.75; p < 0.001) but not in patients with eGRF ≥60 mL/min/1.73 m2 (RR 0.82, 95% CI 0.35-1.94; p = 0.66) at baseline. Furthermore, the increase in serum creatinine was significantly lower in patients with RIPC compared to control patients (standardized mean difference -1.41, 95% CI -2.46 to -0.35; p = 0.009).

CONCLUSIONS

Based on 16 RCTs, this meta-analysis shows that RIPC can reduce the risk of CIN in patients with moderate renal impairment undergoing PCI/CA. However, this needs to be confirmed by further high-quality evidence.

Strong Correlation of Renal Function with Choroidal Thickness in Patients with Type 2 Diabetes: Retrospective Cross-Sectional Study

The purpose of this study was to analyze the correlation between renal function and subfoveal choroidal thickness (SFChT) in treatment-naïve proliferative diabetic retinopathy (PDR) patients. This study included 85 eyes of 52 treatment-naïve PDR patients who underwent kidney function testing and urinalysis and 42 eyes of 33 age-matched controls. Treatment-naïve eyes with PDR were categorized into pachychoroid and leptochoroid groups based on the SFChT of the control group. Kidney function profiles were compared between pachychoroid and leptochoroid groups; the relationship between kidney function profile and SFChT was evaluated using regression analysis. Compared with the pachychoroid group, the leptochoroid group had significantly higher serum creatinine (p = 0.026), cystatin C (p = 0.004), and phosphorus (p < 0.001) levels and a lower estimated glomerular filtration rate (eGFR) (p < 0.001). Multivariate linear regression analyses showed that SFChT was positively correlated with eGFR (Cystatin C) (p = 0.007) and negatively correlated with serum phosphorus (p = 0.001). SFChT of patients with eGFR < 30 mL/min/1.73 m² and serum phosphorus level ≥4.0 mg/dL was less than that of patients with higher eGFR and lower serum phosphorus level. The choroidal thickness of treatment-naïve PDR patients is closely affected by renal function. Kidney function test should be considered if SFChT of patients with treatment-naïve PDR is reduced.

The association between cystatin C and COPD: a meta-analysis and systematic review

BACKGROUND

In recent years, many studies have discovered that cystatin C (Cys C) may play an important role in respiratory diseases, especially in chronic obstructive pulmonary disease (COPD). However, the findings of these studies were inconsistent. This systematic review and meta-analysis aimed to assess the relationship between serum Cys C and COPD.

METHODS

We conducted a systematic literature search in PubMed, Embase, Web of Science, Wanfang databases, and the China National Knowledge Infrastructure. The standardized mean difference (SMD), Fisher's Z-value and 95% confidence interval (CI) were calculated to investigate the effect sizes. Subgroup analyses were performed on disease status, ethnicity, assay method, and study design. Sensitivity was performed, and publication bias was assessed.

RESULTS

A total of 15 studies, including 4079 COPD patients and 5949 controls, were included in this meta-analysis. The results showed that serum Cys C levels in patients with COPD were significantly higher than those in controls (SMD = 0.99, 95% CI =0.62-1.37, P < 0.001), especially in AECOPD (SMD = 1.59, 95% CI =1.05-2.13, P < 0.001), and there were statistically different among AECOPD and SCOPD (SMD = 0.35, 95% CI =0.10-0.59, P = 0.005). The serum Cys C levels were negatively correlated with FEV1%pre (Z = - 0.45, 95%CI = -0.58--0.32, P = 0.011) and FEV1/FVC (Z = - 0.32, 95%CI = -0.50--0.14, P = 0.006). The serum Cys C levels were independent of ethnicity, assay method, and study design.

CONCLUSION

Serum Cys C levels were associated with COPD and COPD exacerbation, and they were inversely correlated with FEV1%pre and FEV1/FVC.

Overestimation of glomerular filtration rate calculated from serum creatinine as compared with cystatin C in patients with subclinical hypercortisolism: Hyogo Adrenal Metabolic Registry

The skeletal muscle mass are decreased in the patients with hypercortisolism. Glomerular filtration rate (eGFR) is not accurately evaluated by calculation from serum creatinine (eGFRcre) in these patients. However, it is not known whether it applies to patients with subclinical hypercortisolism. We investigated the dissociation between eGFRcre and eGFR calculated from cystatin C (eGFRcys) in patients with subclinical hypercortisolism and its association with the skeletal muscle mass. This cross-sectional study includes 23 patients with overt Cushing's syndrome (CS), 84 patients with possible autonomous cortisol secretion (pACS) and 232 patients with non-functioning adenomas (NFA). eGFRcre, eGFRcys, the ratio of eGFRcre to eGFRcys (eGFRcre/eGFRcys) were calculated. Skeletal muscle index (SMI) was measured by a direct segmental multi-frequency bioelectrical impedance body composition analyzer. eGFRcre/eGFRcys was significantly higher (p < 0.01) in pACS (mean ± standard error: 1.15 ± 0.02) than NFA (1.06 ± 0.01). In multiple linear regression analysis, the presence of pACS (β = 0.162, p < 0.01), and post 1 mg-DST cortisol levels (β = 0.190, p < 0.01) were significantly associated with eGFRcre/eGFRcys independent of age, gender, BMI and diabetes. eGFRcre/eGFRcys was significantly and inversely associated with SMI (r = -0.164, p = 0.02). Furthermore, post 1 mg-DST cortisol levels was significantly associated with SMI in simple (r = -0.177, p = 0.01) and multiple (β = -0.089, p = 0.01) regression analyses. In conclusion, dissociation between eGFRcre and eGFRcys was observed in patients with subclinical hypercortisolism at least partly explained by muscle mass. Our findings raise an important clinical point that eGFRcre value should be carefully evaluated even in the phase of subclinical hypercortisolism.

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.

[Factors Resulting Correlation and Differences in Renal Function Evaluation Index Using the Serum Cystatin C and Creatinine as Measured by an Enzymatic Method]

We previously reported the association of the estimated glomerular filtration rate (eGFR_creat) calculated from the serum creatinine level (S-Cr) measured using the Jaffe method with the GFR (eGFR_cys) estimated from the serum cystatin C level (CysC). However, few studies have compared the eGFR_creat using the enzymatic method with the eGFR_cys. It is unclear whether there are differences in the results of renal function assessment. The purpose of this study was to compare the eGFR_creat calculated from the S-Cr with the eGFR_cys calculated from the CysC in patients in whom the S-Cr and CysC were simultaneously measured using the enzymatic method, examine the correlations of respective parameters, and clarify physiological factors involved in differences among the parameters. The subjects were 1334 patients treated in 5 institutions. The mean values and correlation coefficient were statistically analyzed using Student's t-test and Pearson's test, respectively. Influential factors between formulae were analyzed using multiple regression analysis. The mean eGFR_creat was 67.0 mL/min/1.73 m², being significantly higher than the mean eGFR_cys (63.2). Multiple regression analysis showed that factors influencing differences in the S-Cr and CysC included the sex, age, serum albumin, and blood urea nitrogen BUN/S-Cr. Furthermore, factors involved in the overestimation of the eGFR_creat in comparison with the eGFR_cys included the serum albumin and BUN/S-Cr. The differences between the eGFR_creat calculated from the S-Cr and eGFR_cys were less marked than when adopting the Jaffe method in our previous study. However, the eGFR_creat were higher than the eGFR_cys in patients with malnutrition or dehydration.

GFR Measurement and Chemotherapy Dosing in Patients with Kidney Disease and Cancer

Chemotherapeutic agents require precise dosing to ensure optimal efficacy and minimize complications. For those agents that are removed from the body by the kidney, accurate knowledge of GFR is critical. In addition, GFR needs to be determined rapidly, easily, and, if possible, with little additional cost. The ability to easily measure GFR also allows for rapid detection of nephrotoxicity. Current methodologies include direct clearance measurement of an indicator substance or estimation of creatinine clearance or GFR through regression equations that use a serum marker, such as creatinine or cystatin C. These methodologies all have shortfalls and limitations, some of which are specific to the patient with cancer. Newer methodologies that directly measure GFR are in clinical trials and offer the ability to rapidly and noninvasively provide accurate estimates of drug clearance as well as detection of nephrotoxicity. These methods offer the opportunity to refine drug dosing and improve outcomes.