Role of biomarkers in the diagnosis and prognosis of acute kidney injury in patients with cardiorenal syndrome

Calcium-Sensing Receptor (CaSR)-Mediated Intracellular Communication in Cardiovascular Diseases

The calcium-sensing receptor (CaSR), a G-protein-coupled receptor (GPCR), is a cell-surface-located receptor that can induce highly diffusible messengers (IP3, Ca²⁺, cAMP) in the cytoplasm to activate various cellular responses. Recently, it has also been suggested that the CaSR mediates the intracellular communications between the endoplasmic reticulum (ER), mitochondria, nucleus, protease/proteasome, and autophagy-lysosome, which are involved in related cardiovascular diseases. The complex intracellular signaling of this receptor challenges it as a valuable therapeutic target. It is, therefore, necessary to understand the mechanisms behind the signaling characteristics of this receptor in intracellular communication. This review provides an overview of the recent research progress on the various regulatory mechanisms of the CaSR in related cardiovascular diseases and the heart-kidney interaction; the associated common causes are also discussed.

Deciphering key genes in cardio-renal syndrome using network analysis

Cardio-renal syndrome (CRS) is a rapidly recognized clinical entity which refers to the inextricably connection between heart and renal impairment, whereby abnormality to one organ directly promotes deterioration of the other one. Biological markers help to gain insight into the pathological processes for early diagnosis with higher accuracy of CRS using known clinical findings. Therefore, it is of interest to identify target genes in associated pathways implicated linked to CRS. Hence, 119 CRS genes were extracted from the literature to construct the PPIN network. We used the MCODE tool to generate modules from network so as to select the top 10 modules from 23 available modules. The modules were further analyzed to identify 12 essential genes in the network. These biomarkers are potential emerging tools for understanding the pathophysiologic mechanisms for the early diagnosis of CRS. Ontological analysis shows that they are rich in MF protease binding and endo-peptidase inhibitor activity. Thus, this data help increase our knowledge on CRS to improve clinical management of the disease.

Prognostic significance of acute kidney injury and small increases in creatinine concentration during acute decompensation of heart failure

BACKGROUND

Diagnosis of acute kidney injury (AKI) during acute decompensations of heart failure (ADHF) remain challenging. We analysed the incidence and prognosis of AKI, and the significance of small increases of creatinine, during ADHF and after stabilization.

PATIENTS AND METHODS

Patients admitted for ADHF were prospectively included. Creatinine was measured at admission, 48h thereafter and 24h before discharge. AKI was diagnosed when creatinine increased≥50% in 7 days (RIFLE criteria) or≥0.3mg/dL in 48h (AKIN criteria) during admission. Changes between baseline creatinine (measured within 3-month before admission) and one month after discharge were assessed, to seek for residual impairment of renal function and its significance.

RESULTS

Two hundred and four patients were included. Incidence of AKI was 28.4% (n=58). Creatinine peaked by day 5 in patients with AKI vs. non-AKI (1.9 vs. 1.1mg/dL; P<.000) and remained significantly higher among patients with AKI 3 months after discharge (increase of 20 vs. 4%; P=.013). Twelve-months mortality was associated with increases in cystatin C, NT-proBNP and AKI (15.5 vs. 44.8%, P<.000), being the latter the most powerful independent predictor of death ?Exp(B)=5.34; P=.009?. Minor increases in creatinine (20% or 0.2mg/dL) during admission associated lesser 12-months survival (P=.033 and P=.019, respectively). Increases in creatinine≥10% between baseline and one month after discharge are associated with higher mortality (12.6 vs. 22.5%, P=.044).

CONCLUSIONS

AKI is a strong predictor of mortality after ADHF. Minor increments in creatinine concentrations, below the accepted threshold for AKI definition, are prognostically meaningful.

Elevated admission urinary N-acetyl-β-D-glucosamidase level is associated with worse long-term clinical outcomes in patients with acute heart failure

Background:

The prognostic significance of urinary N-acetyl-β-D-glucosamidase in acute heart failure has not been fully elucidated. Accordingly, this study investigated whether urinary N-acetyl-β-D-glucosamidase could be associated with subsequent adverse events in acute heart failure patients.

Methods:

We studied 708 consecutive acute heart failure patients who had accessible N-acetyl-β-D-glucosamidase data on admission from the National Cerebral and Cardiovascular Center Acute Decompensated Heart Failure registry. We assessed the relationship between the admission N-acetyl-β-D-glucosamidase level and the combined endpoint of all-cause death and worsening heart failure. Worsening heart failure was defined as worsening symptoms and signs of heart failure requiring intensification of intravenous therapy such as diuretics, vasodilators and inotropes or initiation of mechanical support after stabilisation with initial treatment during hospitalisation, or readmission due to heart failure after discharge.

Results:

During a median follow-up period of 763 (interquartile range 431–1028) days, higher urinary N-acetyl-β-D-glucosamidase was significantly related to increased events of all-cause death and worsening heart failure. In addition, patients with higher urinary N-acetyl-β-D-glucosamidase and lower estimated glomerular filtration rate on admission had the worst clinical outcomes. In multivariable Cox regression, urinary N-acetyl-β-D-glucosamidase on admission was independently associated with adverse events (hazard ratio 1.19, 95% confidence interval 1.04–1.35) even after adjustment by covariates including the baseline estimated glomerular filtration rate.

Conclusions:

Higher urinary N-acetyl-β-D-glucosamidase level on admission was independently associated with worse clinical outcomes. Our findings indicate the potential value of assessing urinary N-acetyl-β-D-glucosamidase on admission for further risk stratification in patients with acute heart failure.

Tubular and Glomerular Biomarkers of Acute Kidney Injury in Newborns

BACKGROUND

Acute Kidney Injury (AKI) is a sudden decrease in kidney function. In the early period, the highest percentage of AKI occurs among newborns hospitalized in the neonatal intensive care units, especially premature neonates. The prognosis of AKI depends on the type and severity of the cause of an injury, the accuracy and the time of diagnosis and treatment. The concentration of serum creatinine is still the main diagnostic test, although it changes in the course of AKI later than glomerular filtration rate GFR. In addition, the reliability of the determination of creatinine level is limited because it depends on many factors. New studies have presented other, more useful laboratory markers of renal function that can be measured in serum and/or in urine.

OBJECTIVE

The aim of the work was to present the latest data about tubular and glomerular biomarkers of acute kidney injury in newborns.

METHODS

We undertook a structured search of bibliographic databases for peer-reviewed research literature by using focused review topics. According to the conceptual framework, the main idea of research literature has been summarized and presented in this study.

RESULTS

The concentrations of some novel biomarkers are higher in serum and/or urine of term and preterm newborns with AKI, especially in the course of perinatal asphyxia.

CONCLUSION

In this systematic review of the literature, we have highlighted the usefulness of biomarkers in predicting tubular and/or glomerular injury in newborns. However, novel biomarkers need to prove their clinical applicability, accuracy, and cost-effectiveness prior to their implementation in clinical practice.

Comparative analysis of obesity-related cardiometabolic and renal biomarkers in human plasma and serum

The search for biomarkers associated with obesity-related diseases is ongoing, but it is not clear whether plasma and serum can be used interchangeably in this process. Here we used high-throughput screening to analyze 358 proteins and 76 lipids, selected because of their relevance to obesity-associated diseases, in plasma and serum from age- and sex-matched lean and obese humans. Most of the proteins/lipids had similar concentrations in plasma and serum, but a subset showed significant differences. Notably, a key marker of cardiovascular disease PAI-1 showed a difference in concentration between the obese and lean groups only in plasma. Furthermore, some biomarkers showed poor correlations between plasma and serum, including PCSK9, an important regulator of cholesterol homeostasis. Collectively, our results show that the choice of biofluid may impact study outcome when screening for obesity-related biomarkers and we identify several markers where this will be the case.

External Validation of a Pretransplant Biomarker Model (REVERSE) Predictive of Renal Recovery After Liver Transplantation

In patients with end-stage liver disease, the ability to predict recovery of renal function following liver transplantation (LT) remains elusive. However, several important clinical decisions depend on whether renal dysfunction is recoverable after LT. We used a cohort of patients undergoing LT to independently validate a published pre-LT model predictive of post-transplant renal recovery (Renal Recovery Assessment at Liver Transplant [REVERSE]: high osteopontin [OPN] and tissue inhibitor of metalloproteinases-1 [TIMP-1] levels, age < 57, no diabetes). Serum samples pre-LT and 4-12 weeks post-LT (n = 117) were analyzed for kidney injury proteins from three groups of recipients: (1) estimated glomerular filtration rate (eGFR) < 30 mL/minute/1.73 m² prior to and after LT (irreversible acute kidney injury [AKI]), (2) eGFR < 30 mL/minute/1.73 m² prior to LT and >50 mL/minute/1.73 m² after LT (reversible AKI [rAKI]) (3) eGFR > 50 mL/minute/1.73 m² prior to and after LT (no AKI). In patients with elevated pre-LT serum levels of OPN and TIMP-1, recovery of renal function correlated with decreases in the level of both proteins. At 4 weeks post-LT (n = 77 subset), the largest decline in OPN and TIMP-1 was seen in the rAKI group. Validation of the REVERSE model in this independent data set had high area under the curve (0.78) in predicting full post-LT renal recovery (sensitivity 0.86, specificity 0.6, positive predictive value 0.81, negative predictive value 0.69). Our eGFR findings were confirmed using measured GFR. Conclusion: The REVERSE model, derived from an initial training set combining plasma biomarkers and clinical characteristics, demonstrated excellent external validation performance characteristics in an independent patient cohort using serum samples. Among patients with kidney injury pre-LT, the predictive ability of this model may prove beneficial in clinical decision-making both prior to and following transplantation.

Deregulated renal magnesium transport during lipopolysaccharide-induced acute kidney injury in mice

Magnesium (Mg²⁺) abnormalities during sepsis have been reported, but the underlying mechanisms during acute inflammation are poorly understood. We hypothesized that a decrease in GFR and/or changes in transporters or channels for Mg²⁺ could be responsible for the observed Mg²⁺ abnormalities. Therefore, we studied the metabolism of Mg²⁺ in a murine model of endotoxemia. LPS-induced hypermagnesemia was paralleled by a decrease in creatinine clearance and an increase in the fractional excretion of Mg²⁺. In agreement with an altered renal Mg²⁺ handling, endotoxemia decreased the renal expression of claudin (Cldn) 10b, Cldn16, Cldn19, parvalbumin, and of the solute carrier family (Slc) 41a3. Further, LPS increased the renal expression of Cldn14 and Slc41a1. The renal expression of the transient receptor potential melastin (Trpm) 6, Trpm7, and of cyclin M (Cnnm) 2 was unaltered in response to LPS. In vitro studies support a direct effect on the expression of Cldn10b, Cldn14, Cldn16, and Cldn19. Further, endotoxemia increased the fractional excretion of sodium, which was paralleled by a decrease of important renal sodium transporters. In the large intestine, the expression of Trpm7 was increased in response to LPS, whereas the expression of Trpm6 was decreased. Cnnm4 mRNA levels were unchanged in the large intestine. Further, Cldn12 and Na⁺-H⁺ exchanger 3 (Slc9a3) expressions were decreased in the small intestine in response to LPS. Our findings indicate that endotoxemia is associated with hypermagnesemia and a disturbed Mg²⁺ handling. It seems likely that LPS-induced hypermagnesemia is due to the decrease in renal function in response to LPS.

Impact of renal dysfunction on the management and outcome of acute heart failure: results from the French prospective, multicentre, DeFSSICA survey

OBJECTIVES

Cardiorenal syndrome (CRS) is the combination of acute heart failure syndrome (AHF) and renal dysfunction (creatinine clearance (CrCl) ≤60 mL/min). Real-life data were used to compare the management and outcome of AHF with and without renal dysfunction.

DESIGN

Prospective, multicentre.

SETTING

Twenty-six academic, community and regional hospitals in France.

PARTICIPANTS

507 patients with AHF were assessed in two groups according to renal function: group 1 (patients with CRS (CrCl ≤60 mL/min): n=335) and group 2 (patients with AHF with normal renal function (CrCl >60 mL/min): n=172).

RESULTS

Differences were observed (group 1 vs group 2) at admission for the incidence of chronic heart failure (56.42% vs 47.67%), use of furosemide (60.9% vs 52.91%), insulin (15.52% vs 9.3%) and amiodarone (14.33% vs 4.65%); additionally, more patients in group 1 carried a defibrillator (4.78% vs 0%), had ≥2 hospitalisations in the last year (15.52% vs 5.81%) and were under the care of a cardiologist (72.24% vs 61.63%). Clinical signs were broadly similar in each group. Brain-type natriuretic peptide (BNP) and BNP prohormone were higher in group 1 than group 2 (1157.5 vs 534 ng/L and 5120 vs 2513 ng/mL), and more patients in group 1 were positive for troponin (58.2% vs 44.19%), had cardiomegaly (51.04% vs 37.21%) and interstitial opacities (60.3% vs 47.67%). The only difference in emergency treatment was the use of nitrates, (higher in group 1 (21.9% vs 12.21%)). In-hospital mortality and the percentage of patients still hospitalised after 30 days were similar between groups, but the median stay was longer in group 1 (8 days vs 6 days).

CONCLUSIONS

Renal impairment in AHF should not limit the use of loop diuretics and/or vasodilators, but early assessment of pulmonary congestion and close monitoring of the efficacy of conventional therapies is encouraged to allow rapid and appropriate implementation of alternative therapies if necessary.

A clinical, proteomics, and artificial intelligence-driven model to predict acute kidney injury in patients undergoing coronary angiography

Background

Standard measures of kidney function are only modestly useful for accurate prediction of risk for acute kidney injury (AKI).

Hypothesis

Clinical and biomarker data can predict AKI more accurately.

Methods

Using Luminex xMAP technology, we measured 109 biomarkers in blood from 889 patients prior to undergoing coronary angiography. Procedural AKI was defined as an absolute increase in serum creatinine of ≥0.3 mg/dL, a percentage increase in serum creatinine of ≥50%, or a reduction in urine output (documented oliguria of <0.5 mL/kg per hour for >6 hours) within 7 days after contrast exposure. Clinical and biomarker predictors of AKI were identified using machine learning and a final prognostic model was developed with least absolute shrinkage and selection operator (LASSO).

Results

Forty‐three (4.8%) patients developed procedural AKI. Six predictors were present in the final model: four (history of diabetes, blood urea nitrogen to creatinine ratio, C‐reactive protein, and osteopontin) had a positive association with AKI risk, while two (CD5 antigen‐like and Factor VII) had a negative association with AKI risk. The final model had a cross‐validated area under the receiver operating characteristic curve (AUC) of 0.79 for predicting procedural AKI, and an in‐sample AUC of 0.82 (P < 0.001). The optimal score cutoff had 77% sensitivity, 75% specificity, and a negative predictive value of 98% for procedural AKI. An elevated score was predictive of procedural AKI in all subjects (odds ratio = 9.87; P < 0.001).

Conclusions

We describe a clinical and proteomics‐supported biomarker model with high accuracy for predicting procedural AKI in patients undergoing coronary angiography.

Stem cells transplantation positively modulates the heart-kidney cross talk in cardiorenal syndrome type II

INTRODUCTION

We investigated the effects of human amniotic fluid stem cells (hAFS) and rat adipose tissue stromal vascular fraction GFP-positive cells (rSVC-GFP) in a model of cardio-renal syndrome type II (CRSII).

METHODS AND RESULTS

RHF was induced by monocrotaline (MCT) in 28 Sprague-Dawley rats. Three weeks later, four million hAFS or rSVC-GFP cells were injected via tail vein. BNP, sCreatinine, kidney and heart NGAL and MMP9, sCytokines, kidney and heart apoptosis and cells (Cs) engraftment were evaluated. Cell-treated rats showed a significant reduction of serum NGAL and Creatinine compared to CRSII. In both hAFS and rSVC-GFP group, kidney protein expression of NGAL was significantly lower than in CRSII (hAFS p = 0.036 and rSVC-GFP p < 0.0001) and similar to that of controls. In both hAFS and rSVC-GFP treated rats, we observed cell engraftment in the medulla and differentiation into tubular, endothelial and SMCs cells. Apoptosis was significantly decreased in cell-treated rats (hAFS 14.07 ± 1.38 and rSVC-GFP 12.67 ± 2.96 cells/mm²) and similar to controls (9.85 ± 2.1 cell/mm²). TUNEL-positive cells were mainly located in the kidney medulla. Pro-inflammatory cytokines were down regulated in cell-treated groups and similar to controls. In cell-treated rats, kidney and heart tissue NGAL was not complexed with MMP9 as in CRSII group, suggesting inhibition of MMPs activity.

CONCLUSION

Cell therapy produced improvement in kidney function in rats with CRSII. This was the result of interstitial, vessel and tubular cell engraftment leading to tubular and vessel regeneration, decreased tubular cells apoptosis and mitigated pro-inflammatory milieu. Reduction of NGLA-MMP9 complexes mainly due to decrease MMPs activity prevented further negative heart remodeling.

Circulating Biomarkers in Heart Failure

Biological markers have served for diagnosis, risk stratification and guided therapy of heart failure (HF). Our knowledge regarding abilities of biomarkers to relate to several pathways of HF pathogenesis and reflect clinical worsening or improvement in the disease is steadily expanding. Although there are numerous clinical guidelines, which clearly diagnosis, prevention and evidence-based treatment of HF, a strategy regarding exclusion of HF, as well as risk stratification of HF, nature evolution of disease is not well established and requires more development. The aim of the chapter is to discuss a role of biomarker-based approaches for more accurate diagnosis, in-depth risk stratification and individual targeting in treatment of patients with HF.

Biomarkers and echocardiography for evaluating the improvement of the ventricular diastolic function after surgical relief of hydronephrosis

The pathophysiology of cardio-renal syndrome (CRS) is complex. Hydronephrosis caused by urolithiasis may cause cytokine release and lead to cardiac dysfunction. The aim of this study was to evaluate cardiac function changes observed in patients who received double J placement using feasible biomarkers and echocardiography. This was a prospective, single-center study. Eighty-seven patients who presented with acute unilateral hydronephrosis and received ureteroscope stone manipulation were enrolled. Echocardiography and cytokines were measured on the day of the operation and 24 hours after the procedure. Changes before and after surgery were assessed by the paired t-test and Wilcoxon test. Correlation analyses between echocardiographic diastolic indices and cytokine levels were performed using Pearson’s correlation coefficients. Patients with hydronephrosis showed a higher left atrium volume index (LAVI), decreased E', and increased E/ E' ratio, which indicated diastolic dysfunction. Patients with hydronephrosis also exhibited decreased global strain rates during isovolumetric relaxation (SR_IVR) and E/ SR_IVR, which confirmed the diastolic dysfunction. Significant reductions in LAVI, increases in SR_IVR and decreases in E/ SR_IVR were observed after the operation. Biomarkers, such as TGF-β and serum NT-proBNP, were significantly decreased after surgery. In addition, a significant correlation was observed between the post-surgical decrease in TGF-β1 and increase in SR_IVR. Unilateral hydronephrosis causes cardiac diastolic dysfunction, and relieving hydronephrosis could improve diastolic function. Improvements in cardiac dysfunction can be evaluated by echocardiography and measuring cytokine levels. The results of this study will inform efforts to improve the early diagnosis of CRS and prevent further deterioration of cardiac function when treating patients with hydronephrosis.

Renocardiovascular Biomarkers: from the Perspective of Managing Chronic Kidney Disease and Cardiovascular Disease

Mortality among the patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD) remains high because of the very high incidence of cardiovascular disease (CVD) such as coronary artery disease, cardiac hypertrophy, and heart failure. Identifying CVD in patients with CKD/ESRD remains a significant hurdle and the early diagnosis and therapy for CVD is crucial in these patients. Therefore, it is necessary for the better management to identify and utilize cardiovascular (CV) biomarkers in profiling CVD risk and enabling stratification of early mortality. This review summarizes current evidence about renocardiovascular biomarkers: CV biomarkers in patients with CKD as well as with ESRD, emphasizing on the emerging biomarkers: B-type natriuretic peptide, cardiac troponins, copeptin, the biomarker of renal injury (neutrophil gelatinase-associated lipocalin), and the mineral and bone disorder hormone/marker (fibroblast growth factor-23). Furthermore, it discusses their potential roles especially in ESRD and in future diagnostic and therapeutic strategies for CVD in the context of managing cardiorenal syndrome.

Serelaxin in clinical development: past, present and future

The availability of highly purified recombinant human relaxin, serelaxin, has allowed clinical trials to be conducted in several indications and the elucidation of its pharmacology in human subjects. These studies have demonstrated that serelaxin has unique haemodynamic properties that are likely to contribute to organ protection and long-term outcome benefits in acute heart failure. Clinical observations support its consideration for therapeutic use in other patient populations, including those with chronic heart failure, coronary artery disease, portal hypertension and acute renal failure.

LINKED ARTICLES

This article is part of a themed section on Recent Progress in the Understanding of Relaxin Family Peptides and their Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.10/issuetoc.

Type 4 cardiorenal syndrome

The Acute Dialysis Quality Initiative consensus conference proposed a classification of cardiorenal syndrome (CRS), aiming for a better delineation of each subtype. Although the exact pathophysiology of type 4 CRS is not completely understood, the mechanisms involved are probably multifactorial. There is growing evidence that oxidative stress is a major connector in the development and progression of type 4 CRS. Giving its complexity, poor prognosis and increasing incidence, type 4 CRS is becoming a significant public health problem. Patients with chronic kidney disease are particularly predisposed to cardiac dysfunction, due to the high prevalence of traditional cardiovascular risk factors in this population, but the contribution of risk factors specific to chronic kidney disease should also be taken into account. Much remains to be elucidated about type 4 CRS: despite progress over the last decade, there are still significant questions regarding its pathophysiology and there is as yet no specific therapy. A better understanding of the mechanisms involved may provide potential targets for intervention. The present review will provide a brief description of the definition, epidemiology, diagnosis, prognosis, biomarkers and management strategies of type 4 CRS, and the pathophysiological mechanisms and risk factors presumably involved in its development will be particularly highlighted.

Early serum creatinine changes and outcomes in patients admitted for acute heart failure: the cardio-renal syndrome revisited

BACKGROUND

The changes in renal function that occurred in patients with acute decompensated heart failure (ADHF) are prevalent, and have multifactorial etiology and dissimilar prognosis. To what extent the prognostic role of such changes may vary according to the presence of renal insufficiency at admission is not clear. Accordingly, we sought to determine whether early creatinine changes (ΔCr) (admission to 48-72 hours) had an effect on 1-year mortality relative to the presence of renal insufficiency at admission.

METHODS

We included 705 consecutive patients admitted with the diagnosis of ADHF. Admission renal insufficiency was defined as serum creatinine ≥1.4mg/dl (A-RI_cr) or estimated glomerular filtration rate <60ml/min/1.73m² (A-RI_GFR). Appropriate survival regression techniques were used.

RESULTS

The mean age was 72.9±11.4 years and 51.2% were males. Patients with admission renal insufficiency (24.7% and 42.8% for A-RIcr and A-RIGFR, respectively) had higher prevalence of extreme values in ΔCr in either direction (increasing/decreasing). At 1-year follow-up, 114 (16.2%) deaths were registered. The multivariable analysis showed a significant interaction between admission renal insufficiency and ΔCr ( p=0.004 and p=0.019 for A-RIcr and A-RIGFR, respectively). In the presence of renal insufficiency, the continuum of ΔCr followed a positive and almost linear relationship with mortality risk. Conversely, in patients without renal insufficiency, those changes adopted a 'J-shape' trajectory with increased mortality at both ends of the curve distribution.

CONCLUSIONS

In patients with ADHF the effect of ΔCr on 1-year mortality varied according to its magnitude and the presence of admission renal insufficiency. There was a graded-association with mortality when renal insufficiency was present on admission.

Level of urinary liver-type fatty acid-binding protein is associated with cardiac markers and electrocardiographic abnormalities in type-2 diabetes with chronic kidney disease stage G1 and G2

Urinary liver-type fatty acid-binding protein (L-FABP) reflects the degree of stress in proximal tubules of the kidney. We examined the level of L-FABP in type-2 diabetes mellitus (T2DM) patients with chronic kidney disease (CKD) stage G1 and G2, and its relationship with cardiac markers and electrocardiographic (ECG) abnormalities. T2DM patients whose estimated glomerular filtration rate (eGFR) was ≥60 mL/min/1.73 m(2) were recruited [n = 276 (165 males), mean age 64 years]. The median level of urinary L-FABP was 6.6 μg/gCr. Urinary L-FABP showed significant correlation with urinary albumin-to-creatinine ratio (ACR) (r = 0.51, p < 0.0001). Median (25th-75th percentile) eGFR was 82 (72-95) mL/min/1.73 m2. We divided patients into four subgroups (group 1, L-FABP ≤8.4 μg/gCr and ACR ≤30 mg/gCr; group 2, L-FABP ≤8.4 μg/gCr and ACR >30 mg/gCr; group 3, L-FABP >8.4 μg/gCr and ACR ≤30 mg/gCr; group 4, L-FABP >8.4 μg/gCr and ACR >30 mg/gCr). Compared with group 1, group 4 was significantly higher in systolic blood pressure, and eGFR using standardized serum cystatin C, high-sensitivity troponin T, and N-terminal pro-brain natriuretic peptide (NT-proBNP). Group 4 had significantly higher level of NT-proBNP than group 3. Groups 2, 3 and 4 showed more ECG abnormalities than group 1. These findings suggest that simultaneous measurement of urinary L-FABP and ACR should be useful to assess cardiovascular damage reflecting on the elevation of cardiac markers and ECG abnormalities in T2DM with CKD G1 and G2.

The kidney in congestive heart failure: 'are natriuresis, sodium, and diuretics really the good, the bad and the ugly?'

This review discusses renal sodium handling in heart failure. Increased sodium avidity and tendency to extracellular volume overload, i.e. congestion, are hallmark features of the heart failure syndrome. Particularly in the case of concomitant renal dysfunction, the kidneys often fail to elicit potent natriuresis. Yet, assessment of renal function is generally performed by measuring serum creatinine, which has inherent limitations as a biomarker for the glomerular filtration rate (GFR). Moreover, glomerular filtration only represents part of the nephron's function. Alterations in the fractional reabsorptive rate of sodium are at least equally important in emerging therapy-refractory congestion. Indeed, renal blood flow decreases before the GFR is affected in congestive heart failure. The resulting increased filtration fraction changes Starling forces in peritubular capillaries, which drive sodium reabsorption in the proximal tubules. Congestion further stimulates this process by augmenting renal lymph flow. Consequently, fractional sodium reabsorption in the proximal tubules is significantly increased, limiting sodium delivery to the distal nephron. Orthosympathetic activation probably plays a pivotal role in those deranged intrarenal haemodynamics, which ultimately enhance diuretic resistance, stimulate neurohumoral activation with aldosterone breakthrough, and compromise the counter-regulatory function of natriuretic peptides. Recent evidence even suggests that intrinsic renal derangements might impair natriuresis early on, before clinical congestion or neurohumoral activation are evident. This represents a paradigm shift in heart failure pathophysiology, as it suggests that renal dysfunction-although not by conventional GFR measurements-is driving disease progression. In this respect, a better understanding of renal sodium handling in congestive heart failure is crucial to achieve more tailored decongestive therapy, while preserving renal function.