Acute kidney injury as a causal factor in mortality associated with hepatorenal syndrome

Do old urinary biomarkers have a place in the new definition of hepatorenal syndrome in the Egyptian cirrhotic patients? A single-center experience

Background

Hepatorenal syndrome is still a diagnosis of exclusion despite new classification.

Aims

To validate the accuracy of urinary neutrophil gelatinase-associated lipocalin, interleukin-18, and kidney injury molecule-1 in the new diagnostic criteria of hepatorenal syndrome in Egyptian patients with hepatitis C virus-related liver cirrhosis using serum creatinine as a gold standard test for acute kidney injury.

Methods

One-hundred twenty cirrhotic patients with ascites were recruited and divided into two groups depending on the presence or absence of renal impairment, and 40 age- and sex-matched cirrhotic patients without ascites used as controls participated in the study. Urinary biomarkers were measured and compared with conventional biomarkers used to assess kidney function (serum creatinine, estimated glomerular filtration rate).

Results

The mean urinary neutrophil gelatinase-associated lipocalin, interleukin-18, and kidney injury molecule-1 were statistically significantly higher in patients with hepatorenal syndrome and were found to be helpful in the early detection with cutoff values of 125 ng/ml, 34.8 pg/ml, and 3.1 pg/ml, respectively.

Conclusions

Urinary neutrophil gelatinase-associated lipocalin, interleukin-18, and kidney injury molecule-1 levels are higher in patients with cirrhotic ascites complicated by HRS-AKI using the new definition of HRS, but IL-18 has lower sensitivity and specificity for the prediction of HRS-AKI as compared to NGAL and KIM-1.

Admission plasma uromodulin and the risk of acute kidney injury in hospitalized patients with cirrhosis: a pilot study

Acute kidney injury (AKI) is a common complication in hospitalized patients with cirrhosis. Uromodulin, a protein uniquely produced by the kidney and released both in the urine and circulation, has been shown to regulate AKI and is linked to tubular reserve. Although low levels of urine uromodulin are associated with AKI after cardiac surgery, it is unclear whether circulating uromodulin can stratify the risk of AKI, particularly in a susceptible population such as hospitalized patients with cirrhosis. Thus, we investigated whether plasma uromodulin measured at the time of admission is associated with subsequent hospital-acquired AKI (defined by a rise in serum creatinine >0.3mg/dL within 48 h or ≥ 1.5 times baseline) in patients with cirrhosis. A total of 98 patients [mean age 54 yr, Model for Endstage Liver Disease Sodium (MELD-Na) score 19, and baseline creatinine of 0.95 mg/dL] were included, of which 13% (n = 13) developed AKI. Median uromodulin levels were significantly lower in patients who developed AKI compared with patients who did not (9.30 vs. 13.35 ng/mL, P = 0.02). After adjusting for age, sex, diabetes, hypertension, albumin, and MELD-Na score as covariates on multivariable logistic regression, uromodulin was independently associated with AKI [odd ratios of 1.19 (95% confidence interval 1.02, 1.37; P = 0.02)]. Lower uromodulin levels on admission are associated with increased odds of subsequent AKI in hospitalized patients with cirrhosis. Further studies are needed to better understand the role of uromodulin in the pathogenesis and as a predictive biomarker of AKI in this population.NEW & NOTEWORTHY In this study, we found that admission plasma uromodulin levels are significantly lower in patients who developed subsequent acute kidney injury (AKI) during their hospital stay compared with patients who did not. Additionally, uromodulin is independently associated with AKI development after adjusting for clinically relevant parameters such as age, sex, diabetes, hypertension, severity of cirrhosis, and kidney function. To our knowledge, this is the first study linking plasma uromodulin with AKI development in patients with cirrhosis.

Fractional excretion of urea: A simple tool for the differential diagnosis of acute kidney injury in cirrhosis

Current approaches to determine the cause of acute kidney injury (AKI) in patients with cirrhosis are suboptimal. The aim of this study was to determine the utility of fractional excretion of urea (FEUrea) for the differential diagnosis of AKI in patients with cirrhosis. A retrospective analysis was performed in patients (n = 50) with cirrhosis and ascites admitted with AKI. Using adjudicated etiology assessment as the reference standard, receiver operating curves and optimal cutoff, sensitivity (Sn), and specificity (Sp) for the diagnosis of prerenal azotemia (PRA), type 1 hepatorenal syndrome (HRS), and acute tubular necrosis (ATN) were derived. Validation was performed in an independent cohort (n = 50) and by bootstrap analysis. The causes of AKI (derivation:validation cohorts) were: PRA 21:21, HRS 18:15, and ATN 11:14. Median FEUrea was statistically different across all etiologies of AKI in the derivation cohort (PRA 30.1 vs. HRS 20.2 vs. ATN 43.6; P < 0.001) and validation cohort (PRA 23.1 vs. HRS 13.3 vs. ATN 44.7; P < 0.001). The area underneath the curve (cutoff, Sn/Sp) for FEUrea was 0.96 (33.4, 85/100) for ATN versus non-ATN, 0.87 (28.7, 75/83) for HRS versus non-HRS, and 0.81 (21.6, 90/61) for PRA versus HRS. When applied to the validation cohort, Sn/Sp were maintained for ATN versus non-ATN (93/97), HRS versus non-HRS (100/63), and for PRA versus HRS (67/80). After bootstrapping, Sn/Sp for FEUrea in the ATN versus non-ATN, HRS versus non-HRS, and PRA versus HRS was 88/96, 63/97, and 55/87, respectively.

CONCLUSION

FEUrea is a promising tool for the differential diagnosis of AKI in patients with cirrhosis. (Hepatology 2018;68:224-233).

Induction of renal artery hyperresponsiveness by alpha1-adrenoceptor in hepatorenal syndrome

Objective

To investigate the potential role of alpha1-adrenoceptor (α1-AR) in the pathogenesis of hepatorenal syndrome.

Methods

Hepatorenal syndrome was induced in male rats by intraperitoneal injection of D-galactosamine and orally treatment with α1-AR antagonist tamsulosin. Hyperresponsiveness of the renal artery contraction was evaluated by the laser-Doppler flowmetry and multimyograph system, while renal blood flow (cortical and medullary perfusion) was simultaneously measured. Renal artery ring segment tone was recorded with the myograph system, and concentration-response curves were obtained by cumulative administration of agonists.

Results

This model developed acute renal and liver failure without renal damage in pathology, accompanied by significant hyperresponsiveness of renal artery contraction. After hepatorenal syndrome, plasma concentrations of tumor necrosis factor-α increased by two-fold, and α1-AR was significantly activated in the renal artery. Concentration-dependent vasoconstriction induced by noradrenaline was significantly decreased in the renal arteries of hepatorenal syndrome rat because of gradually decreased renal blood flow. Administration of tamsulosin prevented renal failure when given before the onset of liver injury, but it had no effect on liver injury by itself.

Conclusion

α1-AR expression is positively associated with renal vasoconstriction induced by renal artery hyperresponsiveness in HRS. Therefore, α1-AR may be a potential target in the treatment of HRS.

Long-term outcome of severe acute kidney injury survivors followed by nephrologists in a developing country

AIM

This study aimed to evaluate the long-term outcome of patients after a severe episode of acute kidney injury (AKI) on survival and progression to chronic kidney disease (CKD) and to identify risk factors associated with these outcomes.

METHODS

We performed a prospective study that evaluated the long-term outcome of 509 AKI stage 3 patients who were followed by nephrologists in a Brazilian University Hospital from 2004 to 2013.

RESULTS

Age was 60.2 years (47.5-71) and the follow-up time was 25 months (12-44). The late mortality was 38.1% and age (HR 2.89, 95% CI=1.88 to 4.46, P < 0.0001), diabetes (HR 1.46, 95% CI=1 0.02 to 2.16, P < 0.047), liver disease (HR 2.95, 95% CI=1.19 to 7.3, P = 0.02) and creatinine (Cr) at the time of hospital discharge (HR 1.21, 95% CI=1.04 to 1.41, P = 0.01) were associated with poor long-term survival. At the moment of hospital discharge, 52.1% of patients had complete recovery of renal function, 39.7% had partial recovery and 8.3% had not recovered renal function. After 36 months, 43.5% of patients progressed to CKD, and 5.3% needed for chronic dialysis. Factors associated with progression to CKD were age (HR 1.02, 95% CI=1.008 to 1.035, P = 0.009), CKD (HR 1.05 95% CI=1.007 to 1.09, P = 0.04), diabetes (HR 1.12, CI 1.008-1.035, P = 0.009) and number of AKI episodes (HR 1.65, 95% CI=1.19 to 2.2, P = 0.0023).

CONCLUSION

This study showed that AKI patients have high mortality after hospital discharge and age, diabetes, liver disease, and Cr value at the time of discharge were factors associated with long-term mortality. The risk factors for this progression to CKD were age, the presence of diabetes and the number of AKI episodes.

Development of a rat model of D-galactosamine/lipopolysaccharide induced hepatorenal syndrome

AIM: To develop a practical and reproducible rat model of hepatorenal syndrome for further study of the pathophysiology of human hepatorenal syndrome.

METHODS: Sprague-Dawley rats were intravenously injected with D-galactosamine and lipopolysaccharide (LPS) via the tail vein to induce fulminant hepatic failure to develop a model of hepatorenal syndrome. Liver and kidney function tests and plasma cytokine levels were measured after D-galactosamine/LPS administration, and hepatic and renal pathology was studied. Glomerular filtration rate was detected in conscious rats using micro-osmotic pump technology with fluorescein isothiocyanate-labelled inulin as a surrogate marker.

RESULTS: Serum levels of biochemical indicators including liver and kidney function indexes and cytokines all significantly changed, especially at 12 h after D-galactosamine/LPS administration [alanine aminotransferase, 3389.5 ± 499.5 IU/L; blood urea nitrogen, 13.9 ± 1.3 mmol/L; Cr, 78.1 ± 2.9 μmol/L; K⁺, 6.1 ± 0.5 mmol/L; Na⁺, 130.9 ± 1.9 mmol/L; Cl^-, 90.2 ± 1.9 mmol/L; tumor necrosis factor-α, 1699.6 ± 599.1 pg/mL; endothelin-1, 95.9 ± 25.9 pg/mL; P < 0.05 compared with normal saline control group]. Hepatocyte necrosis was aggravated gradually, which was most significant at 12 h after treatment with D-galactosamine/LPS, and was characterized by massive hepatocyte necrosis, while the structures of glomeruli, proximal and distal tubules were normal. Glomerular filtration rate was significantly decreased to 30%-35% of the control group at 12 h after D-galactosamine/LPS administration [Glomerular filtration rate (GFR)₁, 0.79 ± 0.11 mL/min; GFR₂, 3.58 ± 0.49 mL/min·kgBW^-1; GFR₃, 0.39 ± 0.99 mL/min·gKW^-1]. The decreasing timing of GFR was consistent with that of the presence of hepatocyte necrosis and liver and kidney dysfunction.

CONCLUSION: The joint use of D-galactosamine and LPS can induce liver and kidney dysfunction and decline of glomerular filtration rate in rats which is a successful rat model of hepatorenal syndrome.

Kidney biomarkers and differential diagnosis of patients with cirrhosis and acute kidney injury

Acute kidney injury (AKI) is common in patients with cirrhosis and associated with significant mortality. The most common etiologies of AKI in this setting are prerenal azotemia (PRA), acute tubular necrosis (ATN), and hepatorenal syndrome (HRS). Accurately distinguishing the etiology of AKI is critical, as treatments differ markedly. However, establishing an accurate differential diagnosis is extremely challenging. Urinary biomarkers of kidney injury distinguish structural from functional causes of AKI and may facilitate more accurate and rapid diagnoses. We conducted a multicenter, prospective cohort study of patients with cirrhosis and AKI assessing multiple biomarkers for differential diagnosis of clinically adjudicated AKI. Patients (n = 36) whose creatinine returned to within 25% of their baseline within 48 hours were diagnosed with PRA. In addition, 76 patients with progressive AKI were diagnosed by way of blinded retrospective adjudication. Of these progressors, 39 (53%) patients were diagnosed with ATN, 19 (26%) with PRA, and 16 (22%) with HRS. Median values for neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18), kidney injury molecule-1 (KIM-1), liver-type fatty acid binding protein (L-FABP), and albumin differed between etiologies and were significantly higher in patients adjudicated with ATN. The fractional excretion of sodium (FENa) was lowest in patients with HRS, 0.10%, but did not differ between those with PRA, 0.27%, or ATN, 0.31%, P = 0.54. The likelihood of being diagnosed with ATN increased step-wise with the number of biomarkers above optimal diagnostic cutoffs.

CONCLUSION

Urinary biomarkers of kidney injury are elevated in patients with cirrhosis and AKI due to ATN. Incorporating biomarkers into clinical decision making has the potential to more accurately guide treatment by establishing which patients have structural injury underlying their AKI. Further research is required to document biomarkers specific to HRS.

The real importance of pre-existing comorbidities on long-term mortality after acute kidney injury

Background

The causes of death on long-term mortality after acute kidney injury (AKI) have not been well studied. The purpose of the study was to evaluate the role of comorbidities and the causes of death on the long-term mortality after AKI.

Methodology/Principal Findings

We retrospectively studied 507 patients who experienced AKI in 2005–2006 and were discharged free from dialysis. In June 2008 (median: 21 months after AKI), we found that 193 (38%) patients had died. This mortality is much higher than the mortality of the population of São Paulo City, even after adjustment for age. A multiple survival analysis was performed using Cox proportional hazards regression model and showed that death was associated with Khan’s index indicating high risk [adjusted hazard ratio 2.54 (1.38–4.66)], chronic liver disease [1.93 (1.15–3.22)], admission to non-surgical ward [1.85 (1.30–2.61)] and a second AKI episode during the same hospitalization [1.74 (1.12–2.71)]. The AKI severity evaluated either by the worst stage reached during AKI (P = 0.20) or by the need for dialysis (P = 0.12) was not associated with death. The causes of death were identified by a death certificate in 85% of the non-survivors. Among those who died from circulatory system diseases (the main cause of death), 59% had already suffered from hypertension, 34% from diabetes, 47% from heart failure, 38% from coronary disease, and 66% had a glomerular filtration rate <60 previous to the AKI episode. Among those who died from neoplasms, 79% already had the disease previously.

Conclusions

Among AKI survivors who were discharged free from dialysis the increased long-term mortality was associated with their pre-existing chronic conditions and not with the severity of the AKI episode. These findings suggest that these survivors should have a medical follow-up after hospital discharge and that all efforts should be made to control their comorbidities.