Tubular dysfunction in the deeply jaundiced patient with hepatorenal syndrome

Acute hyperbilirubinemia determines an early subclinical renal damage: Evaluation of tubular biomarkers in cholemic nephropathy

BACKGROUND AND AIMS

Cholemic nephropathy is a cause of acute kidney injury occurring in patients with jaundice. The aim of this study was to evaluate early renal function impairment in patients with mild acute hyperbilirubinemia in the absence of alterations of the common parameters used in clinical practice (serum creatinine or urea) and with normal renal morphology. We studied urinary biomarkers of tubular damage urinary neutrophil gelatinase-associated lipocalin (u-NGAL), urinary beta-2-microglobulin (u-B2M), urinary osteopontin (u-OPN), urinary trefoil factor 3 (u-TFF3) and urinary Cystatin C (u-Cys).

METHODS

This is a case-control study investigating the following urinary biomarkers of tubular damage: u-NGAL, u-B2M, u-OPN, u-TFF3 and u-Cys, in patients with mild acute hyperbilirubinemia. Seventy-four patients were included in this study: 36 patients with jaundice and 38 patients without jaundice.

RESULTS

Subjects with jaundice (total bilirubin 12.4 ± 7.3 mg/dL) showed higher u-NGAL, u-B2M, u-OPN, u-TFF3 and u-Cys compared with controls. After logistic regression analyses, including the following independent variables: age, estimated Glomerular Filtration Rate (eGFR), haemoglobin, diabetes, hypertension and jaundice, we observed a higher risk of elevated u-NGAL values (OR = 3.8, 95% CI 1.07-13.5, p = .03) and u-B2M (OR = 9.4, 95% CI 2.3-38.9, p = .0018) in jaundiced subjects. Moreover, urinary biomarkers had a direct correlation with serum cholestasis indexes.

CONCLUSIONS

This study demonstrated increased urinary biomarkers of tubular damage (u-NGAL, u-B2M, u-OPN, u-TFF3, and u-Cys) in patients with mild hyperbilirubinemia in comparison with a control group. These findings suggest early renal tubular damage in the absence of alterations of the normal parameters used in clinical practice (eGFR, serum urea and renal morphology).

Liver Graft Failure and Bile Cast Nephropathy

The consequences of graft failure after liver transplantation (LT) range far beyond the liver. The kidneys are often affected, where persistent and progressive cholestasis can result in acute kidney injury (AKI) leading to the development of bile cast nephropathy (BCN). BCN is an often unrecognized condition that is characterized by proximal tubulopathy and the formation of bile casts in the distal tubules, which is almost diagnosed exclusively on a kidney biopsy or autopsy. This condition is potentially reversible, provided the bilirubin levels can be reduced early. LT may represent a treatment option in the case of irreversible liver (or liver graft) failure, which is beneficial for both the liver and the kidney. This paper reports a case of BCN in a patient with idiopathic graft failure after LT. Despite his chronic kidney disease, liver re-transplantation led to the successful improvement of his AKI.

Bile cast nephropathy: A case report and review of the literature

Bile cast nephropathy is a condition of renal dysfunction in the setting of hyperbilirubinemia. There are very few cases of this condition reported in the last decade and a lack of established treatment guidelines. While the exact etiology remains unknown, bile cast nephropathy is presumed to be secondary to multiple concurrent insults to the kidney including direct toxicity from bile acids, obstructive physiology from bile casts, and systemic hypoperfusion from vasodilation. Therapy directed at bilirubin reduction may improve renal function, but will likely need dialysis or plasmapheresis as well. We report our case of bile cast nephropathy and the therapeutic measures undertaken in a middle-aged male with chronic renal insufficiency that developed hyperbilirubinemia and drug-induced liver injury secondary to antibiotic use. He developed acute renal injury in the setting of rising bilirubin. He subsequently had a progressive decline in renal and hepatic function, requiring dialysis and plasmapheresis with some improvement, ultimately requiring transplantation.

Renal dysfunction in cirrhosis is not just a vasomotor nephropathy

The short-term mortality of cirrhotic patients who develop renal dysfunction remains unacceptably high, and as such the treatment of this condition is an unmet need. Although features of kidney injury are well recognized in these patients, the pathophysiology is complex and not completely understood. Improved understanding of the pathophysiological mechanisms involved in renal dysfunction occurring on a background of cirrhosis is key to developing effective treatment strategies to improve survival. Renal dysfunction due to hepatorenal syndrome (HRS) is characteristic of cirrhosis. Our current understanding is that HRS is functional in nature and occurs as a consequence of hemodynamic changes associated with portal hypertension. However, there is evidence in the literature suggesting that, histologically, the kidneys are not always normal in the vast majority of patients who present with renal dysfunction on the background of cirrhosis. Furthermore, there is emerging data implicating nonvasomotor mechanisms in the pathophysiology of renal dysfunction in cirrhosis. This mini-review aims to present the evidence suggesting that factors other than hemodynamic dysregulation have an important role in the development of this major complication for patients with progressive cirrhosis.

Bile cast nephropathy: an often forgotten diagnosis

High bilirubin levels are nephrotoxic. Bilirubin can cause a functional proximal tubulopathy or may precipitate into casts associated with acute tubular injury. This condition is known as bile cast nephropathy. The kidney injury is generally reversible if bilirubin levels are decreased early. We present a case wherein an alcoholic patient presented with high bilirubin levels and anuric acute kidney injury. The initial urine analysis suggested intrinsic renal disease. A kidney biopsy, performed a few days after the initiation of dialysis, demonstrated the presence of bile casts along with acute tubular injury. The patient however continued to be dialysis dependent inspite of initiating prednisolone to treat acute alcoholic hepatitis.

Urinary biomarkers of acute kidney injury in patients with liver cirrhosis

Acute kidney injury (AKI) is a common complication in cirrhotic patients. Serum creatinine is a poor biomarker for detection of renal impairment in cirrhotic patients. This study aimed to evaluate urinary neutrophil gelatinase-associated lipocalin (NGAL) and urinary interleukin-18 (IL-18) as early biomarkers of acute kidney injury in cirrhotic patients. 160 patients with cirrhosis admitted to the Liver Units at Zagazig University Hospitals were classified into three groups: (I) nonascitic patients, (II) ascitic patients without renal impairment, and (III) ascitic patients with renal impairment. Patients with renal impairment were further divided into four subgroups: [A] prerenal azotemia, [B] chronic kidney disease (CKD), [C] hepatorenal syndrome (HRS), and [D] acute tubular necrosis (ATN). Significant elevation of both urinary NGAL and urinary IL-18 in cirrhotic patients with renal impairment especially in patients with ATN was observed. Urinary NGAL and urinary IL-18 have the ability to differentiate between AKI types in patients with cirrhosis. This could improve risk stratification for patients admitted to the hospital with cirrhosis, perhaps leading to early ICU admission, transplant evaluation, and prompt initiation of HRS therapy and early management of AKI.

Urinary biomarkers of acute kidney injury in patients with liver cirrhosis

BACKGROUND AND AIM

Acute kidney injury is a common complication in cirrhotic patients. Serum creatinine is a poor biomarker for detection of renal impairment in cirrhotic patients. The aim of this study was to evaluate Urinary Neutrophils Gelatinase-Associated Lipocalin (NGAL) and Urinary interleukin-18 (IL-18) as early biomarkers of acute kidney injury in cirrhotic patients.

PATIENTS AND METHODS

160 cirrhotic patients was enrolled in this study divided into 3 main groups according to presence or absence of ascites and renal impairment.

RESULTS

Significant elevation of both Urinary NGAL and Urinary IL-18 in cirrhotic patients with renal impairment especially in patients with Acute tubular necrosis (ATN) was observed. AUROC was (0.909) with (sensitivity 95.5%, specificity 76.1) for Urinary NGAL and AUROC was (0.975), with (sensitivity 95.5%, specificity 91.3%) for Urinary IL-18.

CONCLUSION

Both Urinary NGAL and Urinary IL-18 can act as urinary biomarkers of acute kidney injury in cirrhotic patient.

Acute renal failure in cirrhotic patients with severe sepsis: value of urinary interleukin-18

BACKGROUND AND AIM

Acute renal failure (ARF) is a common complication of liver cirrhosis and severe sepsis. Differentiating functional renal failure from acute tubular necrosis (ATN) has been difficult in this clinical setting. It has been shown that urinary interleukin 18 (IL-18) can serve as a sensitive marker for ARF and ATN. This study was aimed to investigate the diagnostic and prognostic values of urinary IL-18 in ARF associated with liver cirrhosis and severe sepsis.

METHODS

We prospectively evaluated the relationship between urinary IL-18 and clinical outcomes in 168 consecutive cirrhotic patients with severe sepsis.

RESULTS

One hundred and eight patients (64.3%) developed ARF at admission to the intensive care unit. ARF was associated with higher urinary IL-18 and impaired effective arterial volume. Renal failure was functional in 64 (59.2%), due to acute tubular necrosis (ATN) in 30 (27.7%), and mixed type in 14 (12.9%). Patients with ATN had significantly higher levels of urinary IL-18, rates of vasopressor dependency, and hospital mortality than those with functional renal failure. By using the areas under receiver operating characteristic (AUROC) curve, urinary IL-18 demonstrated an excellent discriminative power (AUROC 0.882) for diagnosing tubular injury in those with ARF. Meanwhile, hospital survivors had significantly lower urinary and serum IL-18 levels, compared to non-survivors. In multivariate analysis, urinary IL-18, international normalized ratio, and mean arterial pressure were independent factors to predict hospital mortality.

CONCLUSIONS

Urinary IL-18 can serve as a diagnostic and prognostic marker in cirrhotic patients with severe sepsis.

Acute kidney injury in cirrhosis

Acute renal failure (ARF), recently renamed acute kidney injury (AKI), is a relatively frequent problem, occurring in approximately 20% of hospitalized patients with cirrhosis. Although serum creatinine may underestimate the degree of renal dysfunction in cirrhosis, measures to diagnose and treat AKI should be made in patients in whom serum creatinine rises abruptly by 0.3 mg/dL or more (>/=26.4 micromol/L) or increases by 150% or more (1.5-fold) from baseline. The most common causes of ARF (the term is used interchangeably with AKI) in cirrhosis are prerenal azotemia (volume-responsive prerenal AKI), acute tubular necrosis, and hepatorenal syndrome (HRS), a functional type of prerenal AKI exclusive of cirrhosis that does not respond to volume repletion. Because of the progressive vasodilatory state of cirrhosis that leads to relative hypovolemia and decreased renal blood flow, patients with decompensated cirrhosis are very susceptible to developing AKI with events associated with a decrease in effective arterial blood volume. HRS can occur spontaneously but is more frequently precipitated by events that worsen vasodilatation, such as spontaneous bacterial peritonitis.

CONCLUSION

Specific therapies of AKI depend on the most likely cause and mechanism. Vasoconstrictors are useful bridging therapies in HRS. Ultimately, liver transplantation is indicated in otherwise reasonable candidates in whom AKI does not resolve with specific therapy.

Acute Hepatic Injury and Renal Failure After Ingestion of Snake Gallbladder

Ingestion of snake gallbladder has been practiced in ancient Chinese civilizations to improve vision and relieve arthritic pain. Although little is known about the composition of snake gallbladder, ingestion is still practiced in some Chinese cultures. Adverse effects of ingesting snake gallbladder have not yet been reported. Here, we present a case of acute hepatic injury and delayed-onset renal failure after ingestion of snake gallbladders. The patient subsequently recovered after supportive care, combined with plasma exchange and hemodialysis. He was the only survivor of the four victims suffering from intoxication of snake gallbladder in the last three years in our hospital.

Evidence for megalin-mediated proximal tubular uptake of L-FABP, a carrier of potentially nephrotoxic molecules

Liver-type fatty acid binding protein (L-FABP) binds with high affinity to hydrophobic molecules including free fatty acid, bile acid and bilirubin, which are potentially nephrotoxic, and is involved in their metabolism mainly in hepatocytes. L-FABP is released into the circulation, and patients with liver damage have an elevated plasma L-FABP level. L-FABP is also present in renal tubules; however, the precise localization of L-FABP and its potential role in the renal tubules are not known. In this study, we examined the cellular and subcellular localization of L-FABP in the rat kidney and tried to determine from where the L-FABP in kidney tissues had originated. Immunohistochemical studies of kidney sections localized L-FABP in the lysosomes of proximal tubule cells (PTC). In rats with carbon tetrachloride (CCl4)-induced acute liver injury, we detected high levels of L-FABP in the circulation and in the kidney compared with those in the control rat by immunoblotting, while reverse transcription-polymerase chain reaction showed that the level of L-FABP mRNA expression in the kidney of CCl4-treated rats was low and did not differ from that in the control rat. When 35S-L-FABP was intravenously administered to rats, the kidneys took up 35S-L-FABP more preferentially than the liver and heart, and histoautoradiography of kidney sections revealed that 35S-L-FABP was internalized via the apical domains of PTC. Quartz-crystal microbalance analysis revealed that L-FABP bound to megalin, a multiligand endocytotic receptor on PTC, in a Ca2+-dependent manner. Degradation assays using megalin-expressing rat yolk sac tumor-derived L2 cells demonstrated that megalin mediated the cellular uptake and catabolism of 125I-L-FABP. In conclusion, circulatory L-FABP was found to be filtered by glomeruli and internalized by PTC probably via megalin-mediated endocytosis. These results suggest a novel renal uptake pathway for L-FABP, a carrier of hydrophobic molecules, some of which may exert nephrotoxic effects.

Potential benefit of plasma exchange in treatment of severe icteric leptospirosis complicated by acute renal failure

Leptospirosis is a common zoonosis seen worldwide, but it is rare in our locality (Hong Kong). Clinical manifestations of leptospirosis are variable and may range from subclinical infection to fever, jaundice, hemorrhagic tendency, and fulminant hepato-renal failure. Severe hyperbilirubinemia and acute renal failure have been associated with high mortality. We report our experience with a patient who developed severe Weil's syndrome with marked conjugated hyperbilirubinemia and oliguric acute renal failure. These complications persisted despite treatment with penicillin and hemodiafiltration. Plasma exchange was instituted in view of the severe hyperbilirubinemia (970 micromol/liter). This was followed by prompt clinical improvement, with recovery of liver and renal function. The beneficial effects of plasma exchange could be attributed to amelioration of the toxic effects of hyperbilirubinemia on hepatocyte and renal tubular cell function. We conclude that plasma exchange should be considered as an adjunctive therapy for patients with severe icteric leptospirosis complicated by acute renal failure who have not shown rapid clinical response to conventional treatment.

Reversal of type 1 hepatorenal syndrome with the administration of midodrine and octreotide

The aim of the study was to verify the effects of the administration of an inhibitor of the release of endogenous vasodilators together with a vasoconstrictor agent in patients with hepatorenal syndrome (HRS). This new medical perspective was compared with a traditional medical approach for HRS, such as the infusion of nonpressor doses of dopamine to produce renal vasodilation. Thirteen patients with type 1 HRS were enrolled in the study. Five of them were treated with the oral administration of midodrine and the parenteral administration of octreotide. In addition, the patients received 50 to 100 mL of 20% human albumin solution daily for 20 days. Midodrine and octreotide were dosed to obtain a stable increase of at least 15 mm Hg of mean arterial pressure. Eight patients were treated with the intravenous administration of nonpressor doses of dopamine (2-4 micrograms/kg/min) and the same daily amount of albumin. After 20 days of treatment with midodrine and octreotide, an impressive improvement in renal plasma flow (RPF), glomerular filtration rate, and urinary sodium excretion was observed in patients. This was accompanied by a significant reduction in plasma renin activity, plasma vasopressin, and plasma glucagon. No side effects were observed. Three patients were discharged from the hospital. One of them successfully underwent liver transplantation. One of the two remaining patients is still alive after 472 days with a preserved renal function, and the other died from terminal liver failure after 76 days. One of the two patients who were not discharged from the hospital successfully underwent liver transplantation, and the other died from pneumonia after 29 days. Seven out of eight patients who were treated with dopamine experienced a progressive deterioration in renal function and died during the first 12 days. Only one patient recovered renal function and underwent liver transplantation. In conclusion, the long-term administration of midodrine and octreotide seems to be an effective and safe treatment of type 1 HRS in patients with cirrhosis.

Hypophosphatemia and renal tubular dysfunction in alcoholics. Are they related to liver function impairment?

The study was designed to evaluate (a) the role of reduced renal phosphate reabsorptive capacity assessed as the ratio of maximum capacity for renal phosphate reabsorption (TmPO4) to glomerular filtration rate (GFR) in the pathogenesis of hypophosphatemia in alcoholics, (b) possible mechanisms leading to reduced TmPO4/GFR, and (c) the effect of liver function impairment on TmPO4/GFR. The TmPO4/GFR, its major extrarenal determinants, ratios of urinary excretion gamma-glutamyl transpeptidase and of alpha-glucosidase to GFR (uGGT/GFR and uAGL/GFR), indices of structural damage of renal tubular cells, and fractional clearance of lysozyme, an index of proximal renal function, were evaluated in 31 alcoholics with alcohol-related liver disease, 24 alcoholics without alcohol-related liver disease, 14 patients with non-alcohol-related liver disease, and 25 control subjects. Hypophosphatemia was found in 35% of alcoholics with alcohol-related liver disease, 29% of alcoholics without alcohol-related liver disease, and no patients with non-alcohol-related liver disease. A reduced TmPO4/GFR was the major determinant of hypophosphatemia in both groups of alcoholics. No difference in extrarenal determinants of TmPO4/GFR was found between alcoholics with and without hypophosphatemia. Alcoholics with and without alcohol-related liver disease had increased uGGT/GFR and normal uAGL/GFR regardless of serum phosphate level. Fractional clearance of lysozyme, instead, was increased only in hypophosphatemic alcoholics with and without alcohol-related liver disease. The TmPO4/GFR correlated inversely with the fractional clearance of lysozyme in both groups of alcoholics (P less than 0.01). The TmPO4/GFR and urinary enzymes were normal in patients with non-alcohol-related liver disease. It was concluded that a reduced TmPO4/GFR is involved in the pathogenesis of hypophosphatemia in alcoholics. A proximal tubular dysfunction seems to be responsible for the reduced TmPO4/GFR. Liver function impairment is not required for the expression of this tubular dysfunction.

Analysis of serum and urinary retinol binding protein in hepato-renal syndrome

Retinol binding protein (RBP) was analyzed in the sera and urines of 5 patients with hepato-renal syndrome (HRS), 4 with acute tubular necrosis (ATN), 20 liver cirrhosis patients with normal kidney function (NKF), 14 chronic renal failure (CRF) patients, and 19 healthy adults. All renal failure patients had high mean urine RBP (URBP): HRS, 8 mg/L; ATN, 11 mg/L; CRF, 8 mg/L respectively; p less than 0.001 vs the rest. Those with ATN and CRF had high mean serum RPB (SRBP): 146 and 149 mg/L, respectively, p less than 0.001 compared to the other groups. In HRS, in spite of renal failure, SRBP was very low (mean = 12 mg/L). The cirrhotics with NKF averaged less than 50% of the SRBP values of the healthy controls (16 vs 41 mg/L RBP, p less than 0.001); their RBP excretion was normal (mean URBP of 0.1 vs 0.06 mg/L in the control group). RBP analyses before and during HRS in two patients showed a marked increase in urine RBP during HRS (35- and 600-fold respectively) with practically unchanged serum levels. Impaired hepatic production and/or release is proposed to explain the low serum RBP in HRS, and a renal tubular injury or dysfunction to account for its high excretion. The RBP urinary loss could further compromise an already abnormal RBP metabolism and its serum levels. This combination (of low serum and high urine RBP), in the context of renal failure occurring in alcoholic liver cirrhosis, could help in the recognition of HRS.

Urinary excretion of enzymes in cirrhotics with renal failure

We studied the significance of urinary enzyme measurements in diagnosing proximal tubular damage in cirrhosis of the liver. Urinary excretion (u-enzyme) and fractional urinary excretion (FEenzyme) of gamma-glutamyltranspeptidase (GGT), leucine aminopeptidase (LAP), alkaline phosphatase (AP) and beta-glucuronidase (B-GLU) were quantified in 14 control subjects (group I), 12 cirrhotics with functional renal failure (group II), 13 cirrhotics with renal tubular damage (group III) and 7 non-liver patients with renal tubular damage (group IV). Urinary enzyme excretion and fractional enzyme excretion were significantly higher in the cirrhotics of group III than in the controls or group II. In group III, these tests usually reached values within the range of group IV. The sensitivity of urinary enzyme excretion was 0.92 and specificity ranged from 0.75 (u-LAP) to 1 (u-GGT; u-B-GLU). The sensitivity of fractional enzyme excretion was between 0.61 (FEB-GLU) and 0.84 (FEGGT; FELAP), while specificity was from 0.91 (FELAP; FEAP) to 1 (FEGGT; FEB-GLU). The results indicate that measurement of urinary enzymes may be very useful in diagnosing renal tubular damage in cirrhotic patients with impaired renal function.

Urinary excretion of 6-keto-prostaglandin F1 alpha, thromboxane B2 and prostaglandin E2 in cirrhosis with ascites. Relationship to functional renal failure (hepatorenal syndrome)

The aim of the study was to investigate the urinary excretion of 6-keto-PGF1 alpha (a stable metabolite of PGI2), thromboxane B2 (TxB2; a stable metabolite of TxA2), and PGE2 in 18 normal subjects, 49 cirrhotics with ascites without renal failure (GFR = 90 +/- 4 ml/min, means +/- S.E.M.) and 20 cirrhotics with functional renal failure (FRF) (GFR = 36 +/- 3). The study was made after 5 days on a 50 mEq sodium diet and without diuretics. Plasma renin activity (PRA), plasma norepinephrine concentration (NE) and plasma antidiuretic hormone concentration (ADH) were also measured. Cirrhotics without FRF showed a significantly higher urinary excretion of 6-keto-PGF1 alpha, TxB2 and PGE, (15.9 +/- 1.7 ng/h, 3.0 +/- 0.3 ng/h, and 6.2 +/- 1.0 ng/h) than did normal subjects (9.2 +/- 0.9, 1.3 +/- 0.1 and 2.3 +/- 0.4). On the contrary, the urinary excretion of these prostaglandins was normal or reduced in patients with FRF (5.3 +/- 0.8, 1.3 +/- 0.2 and 1.9 +/- 0.4). PRA, NE and ADH were significantly increased in cirrhotics with FRF (15.2 +/- 3.9 ng/ml/h, 1026 +/- 149 pg/ml and 4.1 +/- 0.3 pg/ml) and in patients without FRF (8.0 +/- 1.4, 667 +/- 67 and 3.9 +/- 0.3) as compared to normal controls (1.3 +/- 0.2, 275 +/- 46 and 2.4 +/- 0.2). These results suggest that renal hemodynamics in cirrhosis depends upon a critical equilibrium between the activity of endogenous vasoconstrictor systems and the renal production of the vasodilator prostaglandins PGI2 and PGE2. In addition, they do not support FRF in cirrhosis being related to an increased renal production of the vasoconstrictor prostaglandin TxA2.