Long-term Renal Outcome of Biopsy-proven Acute Tubular Necrosis and Acute Interstitial Nephritis

BACKGROUND

Although emerging evidence suggest acute kidney injury (AKI) progress to chronic kidney disease (CKD), long-term renal outcome of AKI still remains unclear. Acute tubular necrosis (ATN) is the most common cause of AKI due to ischemia, toxin or sepsis. Acute interstitial nephritis (AIN), caused by drugs or autoimmune diseases is also increasingly recognized as an important cause of AKI. Unlike glomerular diseases, AKI is usually diagnosed in the clinical context without kidney biopsies, and lack of histology might contribute to this uncertainty.

METHODS

Among 8,769 biopsy series, 253 adults who were histologically diagnosed with ATN and AIN from 1982 to 2018 at five university hospitals were included. Demographic and pathological features that are associated with the development of end stage renal disease (ESRD) were also examined.

RESULTS

Rate of non-recovery of renal function at 6 month was significantly higher in the AIN (ATN vs AIN 49.3 vs 69.4%, P = 0.007) with a 2.71-fold higher risk of non- recovery compared to ATN (95% confidence interval [CI], 1.20-6.47). During the mean follow up of 76.5 ± 91.9 months, ESRD developed in 39.4% of patients with AIN, and 21.5% patients of ATN. The risk of ESRD was significantly higher in AIN (23.05; 95% CI, 2.42-219.53) and also in ATN (12.14; 95% CI, 1.19-24.24) compared to control with non-specific pathology. Older age, female gender, renal function at the time of biopsy and at 6 months, proteinuria and pathological features including interstitial inflammation and fibrosis, tubulitis, vascular lesion were significantly associated with progression to ESRD.

CONCLUSION

Our study demonstrated that patients with biopsy proven ATN and AIN are at high risk of developing ESRD. AIN showed higher rate of non-renal recovery at 6 month than ATN.

Preimplant histologic acute tubular necrosis and allograft outcomes

BACKGROUND AND OBJECTIVES

The influence of deceased-donor AKI on post-transplant outcomes is poorly understood. The few published studies about deceased-donor preimplant biopsy have reported conflicting results regarding associations between AKI and recipient outcomes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This multicenter study aimed to evaluate associations between deceased-donor biopsy reports of acute tubular necrosis (ATN) and delayed graft function (DGF), and secondarily for death-censored graft failure, first adjusting for the kidney donor risk index and then stratifying by donation after cardiac death (DCD) status.

RESULTS

Between March 2010 and April 2012, 651 kidneys (369 donors, 4 organ procurement organizations) were biopsied and subsequently transplanted, with ATN reported in 110 (17%). There were 262 recipients (40%) who experienced DGF and 38 (6%) who experienced graft failure. DGF occurred in 45% of kidneys with reported ATN compared with 39% without ATN (P=0.31) resulting in a relative risk (RR) of 1.13 (95% confidence interval [95% CI], 0.9 to 1.43) and a kidney donor risk index-adjusted RR of 1.11 (95% CI, 0.88 to 1.41). There was no significant difference in graft failure for kidneys with versus without ATN (8% versus 5%). In stratified analyses, the adjusted RR for DGF with ATN was 0.97 (95% CI, 0.7 to 1.34) for non-DCD kidneys and 1.59 (95% CI, 1.23 to 2.06) for DCD kidneys (P=0.02 for the interaction between ATN and DCD on the development of DGF).

CONCLUSIONS

Despite a modest association with DGF for DCD kidneys, this study reveals no significant associations overall between preimplant biopsy-reported ATN and the outcomes of DGF or graft failure. The potential benefit of more rigorous ATN reporting is unclear, but these findings provide little evidence to suggest that current ATN reports are useful for predicting graft outcomes or deciding to accept or reject allograft offers.

Effects of Schizolobium parahyba extract on experimental Bothrops venom-induced acute kidney injury

BACKGROUND

Venom-induced acute kidney injury (AKI) is a frequent complication of Bothrops snakebite with relevant morbidity and mortality. The aim of this study was to assess the effects of Schizolobium parahyba (SP) extract, a natural medicine with presumed anti-Bothrops venom effects, in an experimental model of Bothrops jararaca venom (BV)-induced AKI.

METHODOLOGY

Groups of 8 to 10 rats received infusions of 0.9% saline (control, C), SP 2 mg/kg, BV 0.25 mg/kg and BV immediately followed by SP (treatment, T) in the doses already described. After the respective infusions, animals were assessed for their glomerular filtration rate (GFR, inulin clearance), renal blood flow (RBF, Doppler), blood pressure (BP, intra-arterial transducer), renal vascular resistance (RVR), urinary osmolality (UO, freezing point), urinary neutrophil gelatinase-associated lipocalin (NGAL, enzyme-linked immunosorbent assay [ELISA]), lactate dehydrogenase (LDH, kinetic method), hematocrit (Hct, microhematocrit), fibrinogen (Fi, Klauss modified) and blinded renal histology (acute tubular necrosis score).

PRINCIPAL FINDINGS

BV caused significant decreases in GFR, RBF, UO, HcT and Fi; significant increases in RVR, NGAL and LDH; and acute tubular necrosis. SP did not prevent these changes; instead, it caused a significant decrease in GFR when used alone.

CONCLUSION

SP administered simultaneously with BV, in an approximate 10∶1 concentration, did not prevent BV-induced AKI, hemolysis and fibrinogen consumption. SP used alone caused a decrease in GFR.

Hypoxia inducible factor 1-alpha (HIF-1 alpha) is induced during reperfusion after renal ischemia and is critical for proximal tubule cell survival

Acute tubular necrosis (ATN) caused by ischemia/reperfusion (I/R) during renal transplantation delays allograft function. Identification of factors that mediate protection and/or epithelium recovery could help to improve graft outcome. We studied the expression, regulation and role of hypoxia inducible factor 1-alpha (HIF-1 α), using in vitro and in vivo experimental models of I/R as well as human post-transplant renal biopsies. We found that HIF-1 α is stabilized in proximal tubule cells during ischemia and unexpectedly in late reperfusion, when oxygen tension is normal. Both inductions lead to gene expression in vitro and in vivo. In vitro interference of HIF-1 α promoted cell death and in vivo interference exacerbated tissue damage and renal dysfunction. In pos-transplant human biopsies, HIF-1 α was expressed only in proximal tubules which exhibited normal renal structure with a significant negative correlation with ATN grade. In summary, using experimental models and human biopsies, we identified a novel HIF-1 α induction during reperfusion with a potential critical role in renal transplant.

Acute renal failure in the medical ICU still predictive of high mortality

BACKGROUND

We aimed to determine the outcome and certain predictors of outcome for acute renal failure (ARF) in the medical intensive care unit (ICU) at Tygerberg Hospital.

METHOD

We conducted a retrospective, single-centre cohort study over 12 months comprising all patients admitted to the medical ICU with all causes of renal failure or who developed renal failure following admission to the ICU.

RESULTS

Of 198 medical patients admitted to the ICU, ARF occurred in 46 (23.2%). The leading cause of ARF was acute tubular necrosis. The ICU mortality for ARF patients was 47.8%, compared with 17.5% in ICU patients without ARF. Acute haemodialysis was performed in only 17.3% of the 46 ARF patients. Using Cox proportional hazard regression, we found that mean duration of stay (p<0.001), acute physiology and chronic health evaluation II (Apache II) score (p<0.001), mechanical ventilation (p<0.01), dialysis (p<0.04) and multi-organ failure (p<0.05) affected survival time.

CONCLUSIONS

We found that ARF is still associated with a high mortality rate and longer duration of stay, higher Apache II score, and need for mechanical ventilation; dialysis and presence of multi-organ failure were indicators of a higher mortality rate.

[Complex etiology of acute renal failure in a newborn]

Acute renal failure (ARF), which is diagnosed in 3.4-20% of newborns, is polyetiological in most cases. We present a newborn with non-oliguric ARF diagnosed in the first day of life, and caused by asphixia, intrauterine infection (IUI) and nephrotoxic effects of metotrexate treatment during pregnancy. Antibiotics, including netilmicin and vankomycin, were given because of IUI and infected central venous catheter. Dosage of drugs was adjusted to renal failure parameters, but monitoring of their serum levels was not available. It could cause augmented acute tubular necrosis and interstitial nephritis. Analysis of ARF risk factors in newborns helps in early diagnosis of renal damage and in prompt implementation of therapy.

Pre-Renal Azotemia: A Flawed Paradigm in Critically Ill Septic Patients?

The term pre-renal azotemia (or on occasion 'pre-renal renal failure') is frequently used in textbooks and in the literature to indicate an acute syndrome characterized by the presence of an increase in the blood concentration of nitrogen waste products (urea and creatinine). This syndrome is assumed to be due to loss of glomerular filtration rate but is not considered to be associated with histopathological renal injury. Thus, the term is used to differentiate 'functional' from 'structural' acute kidney injury (AKI) where structural renal injury is taken to indicate the presence of so-called acute tubular necrosis (ATN). This paradigm is well entrenched in nephrology and medicine. However, growing evidence from experimental animal models, systematic analysis of the human and experimental literature shows that this paradigm is not sustained by sufficient evidence when applied to the syndrome of septic AKI, especially in critically ill patients. In such patients, several assumptions associated with the 'pre-renal azotemia paradigm' are violated. In particular, there is no evidence that ATN is the histopathological substrate of septic AKI, there is no evidence that urine tests can discriminate 'functional' from 'structural' AKI, there is no evidence that any proposed differentiation leads or should lead to different treatments, and there is no evidence that relevant experimentation can resolve these uncertainties. Given that septic AKI of critical illness now accounts for close to 50% of cases of severe AKI in developed countries, these observations call into question the validity and usefulness of the 'pre-renal azotemia paradigm' in AKI in general.

Possible mechanisms explaining the tendency towards interstitial fibrosis in aristolochic acid-induced acute tubular necrosis

BACKGROUND

We explored possible mechanisms responsible for the inability of plerosis and the tendency towards fibrosis in aristolochic acid-induced acute tubular necrosis (AA-ATN).

METHODS

Renal biopsy tissues from eight AA-ATN cases were examined. Tubulointerstitial injury was semiquantitatively assessed. Immunohistochemical steptavidin-peroxide (SP) methods were used to determine the expressions of proliferating cell nuclear antigen (PCNA), epidermal growth factor (EGF), alpha-smooth muscle actin (alpha-SMA), transforming growth factor-beta(1) (TGF-beta(1)), connecting tissue growth factor (CTGF), fibronectin (FN), collagen III (Col-III), collagen IV (Col-IV), factor VIII-related antigen (VIII-Ag) and vascular endothelial growth factor (VEGF). Ultramicrostructure of endothelial cells and basement membrane of peritubular capillaries (PTC) and glomerular capillaries was detected by electron microscopy. These data were compared with that of 9 cases of antibiotic-induced ATN (a-ATN) and 10 cases of minor mesangioproliferative non-IgA glomerulonephritis, which served as a control group.

RESULTS

In AA-ATN, almost no renal tubular epithelial cells (RTEC) were PCNA-positive (0.01 +/- 0.02%), and EGF expression was considerably decreased (9.55 +/- 7.22%). This was in contrast with the highly active tubular proliferation (PCNA-positive RTEC 47.25 +/- 19.33%, P < 0.05) and increased EGF expression in a-ATN (64.38 +/- 19.22%, P < 0.05). The expression of alpha-SMA in the tubulointerstitium, the number of interstitial TGF-beta(1)-positive cells and the CTGF-positive interstitial area were all increased in both a-ATN and AA-ATN, with no obvious differences between the two groups. With respect to extracellular matrix (ECM) deposition, FN, Col-III and Col-IV were detected only in the interstitium of AA-ATN. PTC lumina were decreased in size and misshapen in the AA-ATN group. Also in AA-ATN, the luminal wall was partially disrupted, endothelial cells were swollen and vacuoles and granules were found in the cell plasma. Parts of the endothelial cells were detached from the tubular basement membrane.

CONCLUSION

The strong ability for RTEC repair after acute injury was severely diminished in AA-ATN, and this effect may be partly due to reduced EGF expression. Anti-fibrosis mechanisms may also be impaired in AA-ATN, since both a-ATN and AA-ATN had increased expression of TGF-beta(1) and CTGF, whereas only the latter group showed ECM deposition. Injury and loss of PTC occurred in AA-ATN, and this may contribute to tubulointerstitial damage, the inability of plerosis and the tendency towards fibrosis in this disease.

Renal recovery from acute tubular necrosis requiring renal replacement therapy: a prospective study in critically ill patients

BACKGROUND

Data on the incidence of end-stage renal disease (ESRD) resulting from irreversible acute tubular necrosis (ATN) are controversial. This prospective cohort study was designed to assess the need for short- and long-term dialysis in critically ill patients with severe ATN and to define risk factors for lack of renal recovery.

METHODS

433 consecutive patients with clinically diagnosed severe ATN necessitating renal replacement therapy were enrolled. Eight patients were excluded because renal biopsy revealed another cause of acute renal failure. None of the remaining 425 patients had pre-existing chronic renal insufficiency. Primary outcome criteria were recovery of renal function at discharge and ESRD status at 1 year follow-up.

RESULTS

The overall in-hospital mortality of the cohort was 47%. At discharge, 57% of the 226 surviving patients had normal renal function, 33% had mild to moderate renal failure (serum creatinine: 1.3-3 mg/dl) and 10% had severe renal failure (serum creatinine: 3-6 mg/dl). Multivariate analysis showed that neither patient characteristics (age, gender, comorbid conditions), severity of illness (APACHE III, number of failed organs) nor mode and duration of renal replacement therapy were related to recovery of renal function. After 1 year, 76 of the surviving patients had died and in one patient chronic renal failure had progressed to ESRD.

CONCLUSIONS

If critically ill patients with normal renal function prior to the renal insults survive the precipitating cause of ATN, the overwhelming majority will recover sufficient renal function.

Nephrogenic fibrosing dermopathy in a patient with acute renal failure never requiring dialysis

Nephrogenic fibrosing dermopathy (NFD) is a newly recognized cutaneous fibrosing disorder. To date the etiology, pathogenesis, and clinical course remains unknown. The majority of cases have been in renal dialysis or renal transplant patients. Only four cases have been reported in which patients had acute renal failure and never required dialysis. Currently, there is no effective treatment. A 65-year-old man was hospitalized for pneumonia. During hospitalization he developed acute renal failure secondary to acute tubular necrosis. The patient had woody indurated plaques on his upper extremities and trunk, and brown indurated plaques on his trunk. Histopathological examination revealed a spindle cell proliferation infiltrating through the dermis and subcutis with mild mucin deposition. Nephrogenic fibrosing dermopathy is a novel fibrosing disorder diagnosed clinically and histopatholigically. Currently no risk factors other than renal failure have been identified. Our patient is a unique example of NFD observed in acute renal failure secondary to acute tubular necrosis, never requiring dialysis. We also review the four other cases of acute NFD never requiring dialysis that have been reported in the literature.

Macroscopic Hematuria in a Kidney Transplant Recipient: A Rare Cause

Pseudoaneurysm formation in a renal transplant is an uncommon complication of such interventional procedures as percutaneous nephrostomy or renal biopsy; symptoms may be delayed for days or even years. Presentation may vary from incidental discovery to worsening renal insufficiency to life-threatening hemorrhage. We report a case of macroscopic hematuria from a pseudoaneurysm that developed in a kidney transplant recipient after placement of a percutaneous nephrostomy tube. This patient was treated with transcatheter embolization, which is highly effective. A high index of suspicion, along with early diagnosis and transcatheter embolization, are essential for the management of hematuria caused by pseudoaneurysm formation from percutaneous nephrostomy tube placement.

Lambda Light Chain Deposition Disease in a Renal Allograft

Light chain deposition disease (LCDD) of the kidney is characterized by deposition of monoclonal light chains predominantly in glomeruli and in tubular basement membranes. The disease is frequently associated with a lymphoproliferative disorder, and the majority of cases are caused by deposition of kappa light chains. Although the occurrence of de novo multiple myeloma after renal transplantation is uncommon, there are several reports of LCDD involving renal allografts, either de novo or in patients with a diagnosis of LCDD prior to transplantation. To the best of our knowledge, all previously described cases in allografts have been in patients with kappa chain deposition. The relative importance of intrinsic properties of the kidney in predisposing to either kappa or lambda light chain deposition is not known. We present a case of LCDD caused by deposition of lambda light chains in a patient who received a cadaveric renal transplant.

Renal failure secondary to acute tubular necrosis: epidemiology, diagnosis, and management

Acute tubular necrosis (ATN) is a form of acute renal failure (ARF) that is common in hospitalized patients. In critical care units, it accounts for about 76% of cases of ARF. Despite the introduction of hemodialysis > 30 years ago, the mortality rates from ATN in hospitalized and ICU patients are about 37.1% and 78.6%, respectively. The purpose of this review is to discuss briefly the cause, diagnosis, and epidemiology of ARF, and to review in depth the clinical trials performed to date that have examined the influence of growth factors, hormones, antioxidants, diuretics, and dialysis. In particular, the role of the dialysis modality, dialyzer characteristics, and dosing strategies are discussed.

Acetaminophen-induced anion gap metabolic acidosis and 5-oxoprolinuria (pyroglutamic aciduria) acquired in hospital

A rare cause of high anion gap acidosis is 5-oxoproline (pyroglutamic acid), an organic acid intermediate of the gamma-glutamyl cycle. Acetaminophen and several other drugs have been implicated in the development of transient 5-oxoprolinemia in adults. We report the case of a patient with lymphoma who was admitted for salvage chemotherapy. The patient subsequently developed fever and neutropenia and was administered 20.8 g of acetaminophen during 10 days. During this time, anion gap increased from 14 to 30 mEq/L (14 to 30 mmol/L) and altered mental status developed. After usual causes of high anion gap acidosis were ruled out, a screen for urine organic acids showed 5-oxoproline levels elevated at 58-fold greater than normal values. Predisposing factors in this case included renal dysfunction and sepsis. Clinicians need to be aware of this unusual cause of anion gap acidosis because it may be more common than expected, early discontinuation of the offending agent is therapeutic, and administration of N -acetylcysteine could be beneficial.

Urinary protein and enzyme excretion as markers of tubular damage

PURPOSE OF REVIEW

In this review we intend to evaluate the clinical usefulness of measurement of urinary excretion of microproteins and tubular enzymes.

RECENT FINDINGS

Studies of patients with acute tubular necrosis showed that the excretion of some well known enzymes and of new markers such as kidney injury molecule-1 has higher value than classic renal function tests for the early detection of the disease as well as for the prediction of the development of overt acute renal failure. Tubular dysfunction may be detected by measurement of the excretion of tubular enzymes and microproteins not only in workers chronically exposed to heavy metals but also in population exposed to low environmental level below the limits set by the WHO. In chronic glomerulonephritis the excretion of alpha1-microglobulin is significantly associated with the extent of tubulo-interstitial damage and predicts outcome better than proteinuria/day; in the same diseases NAG excretion is significantly dependent on immunoglobulin G and alpha1-microglobulin excretion and predicts remission, progression and response to therapy.

SUMMARY

The measurement of urinary excretion of tubular enzymes and microproteins may be clinically useful in several different kidney diseases (such as acute tubular necrosis, glomerulonephritis) both for diagnosis and prediction of fractional outcome.

Spontaneous renal allograft rupture without acute rejection

Renal allograft rupture (RAR) is a rare but potentially serious complication in the transplanted recipients. The most common cause is acute rejection. We report four cases (0.5%) of RAR occurred in a series of 778 consecutive kidney transplantations due to severe acute tubular necrosis and renal vein thrombosis with no evidence of acute rejection. Transplant nephrectomy was performed in three patients, whereas graft repair was achieved in one patient. These data suggest that RAR may be associated with renal vein thrombosis or severe acute tubular necrosis in absence of acute rejection. Frequently nephrectomy is necessary, but conservative surgical treatment should be attempted to preserve the allograft in selected cases.

[Acute renal failure in a patient with myelodysplastic syndrome and paroxysmal nocturnal hemoglobinuria phenotype]

Hemoglobin and myoglobin heme pigments and iron have acute and chronic nephrotoxic effects, which are often associated with massive hemolysis and rhabdomyolysis. We report a patient with a myelodysplastic syndrome and paroxysmal nocturnal hemoglobinuria phenotype who developed an acute renal failure after a severe haemolytic crisis. There was not evidence of renal vascular pathology, urinary tract obstruction or prerenal factors. Renal biopsy showed features of acute tubular necrosis, with extended iron deposits in tubule cell cytoplasm and tubulo-interstitial fibrosis and atrophy. The patient was oliguric requiring hemodialisys during three weeks, recovering renal function on the fourth week after admission. This case underlines the nephrotoxic role of heme pigment and iron, and possible pathophysiologic mechanisms involved in acute and chronic toxicity of both agents are reviewed.

Renal allograft rupture caused by acute tubular necrosis

Renal allograft rupture is a rare but potentially lethal complication of kidney transplantation. A renal allograft recipient receiving quadruple immunosuppressive therapy developed a spontaneous allograft rupture 13 days after kidney transplantation. Warm ischaemia time during the transplant was 80 minutes. The ruptured kidney graft could not be salvaged because of the patient's haemodynamic instability. The histopathological examination showed interstitial oedema with severe acute tubular necrosis with no signs of acute rejection. The most common causes of renal graft rupture are acute rejection and vein thrombosis, while acute tubular necrosis may only rarely be responsible for this complication. Renal graft rupture may be the result of interstitial damage attributed both to the prolonged warm ischaemia time during the transplant and to post-transplant acute tubular necrosis in the absence of graft rejection. In those patients whose haemodynamic status cannot be stabilized by appropriate aggressive haemodynamic support therapy, graft nephrectomy should be considered the only definitive treatment.

Urinary measurement of Na+/H+ exchanger isoform 3 (NHE3) protein as new marker of tubule injury in critically ill patients with ARF

BACKGROUND

It has been shown that apical sodium transporters of the renal tubule can be detected by immunoblotting of urine membrane fraction from rats. We raised the hypothesis that protein levels of the Na+/H+ exchanger isoform 3 (NHE3), the most abundant apical sodium transporter in renal tubule, should be increased in urine of patients presenting with acute renal failure (ARF) with severe tubular cell damage and thus might be a noninvasive marker of acute tubular necrosis (ATN).

METHODS

Sixty-eight patients admitted to the intensive care unit were studied prospectively (54 patients with ARF, 14 controls without renal dysfunction). Patients with ARF were divided into 3 subgroups as follows: prerenal azotemia, ATN, and intrinsic ARF other than ATN. Urinary NHE3 protein abundance was estimated from semiquantitative immunoblots of urine membrane fraction samples collected from patients. The amount of urinary NHE3 was compared with the fractional excretion of sodium (FeNa) and urinary retinol-binding protein (RBP).

RESULTS

NHE3 was not detected in urine from controls. Levels of urinary NHE3 normalized to urinary creatinine level were increased in patients with prerenal azotemia and 6 times as much in patients with ATN, without overlap (ATN, 0.78 +/- 0.36; prerenal azotemia, 0.12 +/- 0.08; P < 0.001). Conversely, urinary NHE3 protein was not detected in patients with intrinsic ARF other than ATN. Normalized NHE3 level correlated positively with serum creatinine level in patients with tubular injury (R2 = 0.305; P = 0.0003). Values for FeNa and normalized urinary RBP did not discriminate ATN from intrinsic ARF other than ATN and prerenal azotemia, respectively.

CONCLUSION

In patients with ARF, urinary NHE3 abundance might be a novel noninvasive marker of renal tubule damage, helping to differentiate prerenal azotemia, ATN, and intrinsic ARF other than ATN.

Sirolimus-induced thrombotic microangiopathy in a renal transplant recipient

A rare but well-documented serious adverse reaction to the administration of the calcineurin inhibitors tacrolimus and cyclosporine in renal transplant recipients is the development of medication-induced thrombotic microangiopathy. The recently introduced immunosuppressive medication sirolimus has a very similar molecular structure to tacrolimus and also binds to the same intracellular proteins. Despite these similarities with tacrolimus, sirolimus has a different side-effect profile and reportedly lacks documented specific renal toxicity. This is a case report of the isolated administration of sirolimus without a concomitant calcineurin inhibitor being associated with the development of renal transplant biopsy-proven thrombotic microangiopathy. The patient is a 47-year-old African-American woman whose primary cause of renal failure was not thrombotic micrangiopathy, and she received a 5-antigen mismatched cadaveric renal transplant. Because of preexisting nephrosclerosis in the renal transplant, this patient was never administered a calcineurin inhibitor but was always maintained on sirolimus. With recent animal data showing that sirolmus can be nephrotoxic in a renal ischemic-reperfusion model (similar to what happens with a renal transplant), the authors speculate on a mechanism for this adverse reaction.

Acute renal failure in patients with glomerular diseases: a consequence of tubular cell damage caused by haematuria?

We describe three patients with acute renal failure after the onset of gross haematuria. In all patients a presumptive diagnosis of rapidly progressive glomerulonephritis was made and immunosuppressive therapy initiated. A renal biopsy was performed in two patients, which showed evidence of IgA nephropathy. Extracapillary proliferation was seen in a few glomeruli. The most notable abnormality was acute tubular necrosis with intraluminal erythrocytes and cell debris. In the third patient, who was known to have longstanding glomerular haematuria, acute tubular necrosis was considered likely after review of the urinary sediment. Despite the fact that immunosuppressive therapy was stopped, renal function rapidly returned to normal in all these patients. We feel that our patients and additional literature data demonstrate that in patients with glomerular disease a reversible acute renal failure can occur that is caused by acute tubular necrosis mediated by haematuria. Recognition of this entity will prevent unnecessary long-term immunosuppressive therapy.

Case series of thrombotic thrombocytopenic purpura in children and adolescents

Thrombotic thrombocytopenic purpura (TTP) is a well-described entity in adults but is rarely observed in children. The authors describe a series of seven children with suspected acquired TTP. Clinical findings included petechiae, purpura, or jaundice ( 6), central nervous system events ( 5), fever ( 3), diarrhea ( 3), renal insufficiency ( 2), and hematuria ( 2). Significant central nervous system events included cerebral vascular accidents ( 2), altered mental status ( 2), seizures ( 1), and hemiparesis ( 1). Patients were treated with daily plasma infusions (1/7) or plasma exchange (5/7). Response was prompt, although relapses were frequent. Decreased vWF-protease activity was found in four of five cases and vWF-protease inhibitors were found in three of five cases. Although rare, TTP is a life-threatening illness that does occur in children and should be considered in the differential diagnosis of thrombocytopenia with hemolytic anemia.

Measurement of tubular enzymuria facilitates early detection of acute renal impairment in the intensive care unit

BACKGROUND

Early detection of acute tubular necrosis (ATN) could permit implementation of salvage therapies and improve patient outcomes in acute renal failure (ARF). The utility of single and combined measurements of urinary tubular enzymes in predicting ARF in critically ill patients has not been evaluated using the receiver-operating characteristic (ROC) plot method.

METHODS

In this prospective pilot study, 26 consecutive critically ill adult patients admitted to the intensive-care unit were studied. Urine samples were collected twice daily for up to 7 days. ARF was defined as an increase in plasma creatinine of > or = 50% and > or = 0.15 mmol/l. ROC plot analysis was applied to the tubular marker data to derive optimum cut-offs for ARF.

RESULTS

Four of the 26 study subjects (15.4%) developed ARF. Indexed to urinary creatinine concentration, gamma glutamyl transpeptidase (gamma GT), alkaline phosphatase (AP), N-acetyl-glucosaminidase (NAG), and alpha- and pi-glutathione S-transferase (alpha- and pi-GST) but not lactate dehydrogenase (LDH) were higher in the ARF group on admission (P<0.05). gamma GT, and alpha- and pi-GST remained elevated at 24 h. The onset of ARF based on changes in plasma creatinine varied from 12 h to 4 days (median 36 h). ROC plot analysis showed that gamma GT, pi-GST, alpha-GST, AP and NAG had excellent discriminating power for ARF (AUC 0.950, 0.929, 0.893, 0.863 and 0.845, respectively). The discriminating strength of creatinine clearance, while lower, was still significant (AUC 0.796). Positive and negative predictive values for ARF on admission were 67/100% for gamma GT, 67/90% for AP, 60/95% for alpha-GST, and 67/100% for pi-GST indices. Positive and negative predictive values for ARF for creatinine clearance < or = 23 ml/min were 50 and 91%, respectively. Creatinine clearances tended to be lower in ARF than in non-ARF patients on admission (P=0.06) and were significantly lower (P=0.008) after 12 h. Plasma urea and fractional sodium excretion were unhelpful.

CONCLUSIONS

Tubular enzymuria on admission to the ICU is useful in predicting ARF. The cheapness and wide availability of automated assays for gamma GT and AP suggests that estimation of these enzymes in random urine samples may be particularly useful for identifying patients at high risk of ARF.

Acute renal failure in patients with cirrhosis: perspectives in the age of MELD

In patients with cirrhosis, acute renal failure is mainly due to prerenal failure (caused by renal hypoperfusion) and tubular necrosis. The main causes of prerenal failure are "true hypovolemia" (induced by hemorrhage or gastrointestinal or renal fluid losses), sepsis, or type 1 hepatorenal syndrome (HRS). The frequency of prerenal failure due to the administration of nonsteroidal anti-inflammatory drugs or intravascular radiocontrast agents is unknown. Prerenal failure is rapidly reversible after restoration of renal blood flow. Treatment is directed to the cause of hypoperfusion, and fluid replacement is used to treat most cases of "non-HRS" prerenal failure. In patients with type 1 HRS with very low short-term survival rate, liver transplantation is the ideal treatment. Systemic vasoconstrictor therapy (with terlipressin, noradrenaline, or midodrine [combined with octreotide]) may improve renal function in patients with type 1 HRS waiting for liver transplantation. MARS (for molecular adsorbent recirculating system) and the transjugular intrahepatic portosystemic shunt may also improve renal function in these patients. In patients with cirrhosis, acute tubular necrosis is mainly due to an ischemic insult to the renal tubules. The most common condition leading to ischemic acute tubular necrosis is severe and sustained prerenal failure. Little is known about the natural course and treatment (i.e., renal replacement therapy) of cirrhosis-associated acute tubular necrosis.

Diagnosis and treatment of acute tubular necrosis

BACKGROUND

Acute tubular necrosis (ATN) is common in hospitalized patients, particularly in the intensive care unit. Over the past four decades, the mortality rate from ATN has remained at 50% to 80%.

PURPOSE

To review recent studies of diagnosis and treatment strategies for ATN.

DATA SOURCES

MEDLINE search for all clinical studies of therapies for ATN, supplemented by a review of the references of the identified articles.

STUDY SELECTION

Prospective studies and major retrospective studies evaluating therapies for ATN.

DATA EXTRACTION

Data on the study sample, interventions performed, results, side effects, and duration of follow-up.

DATA SYNTHESIS

Early diagnosis of ATN by exclusion of prerenal and postrenal causes of acute renal failure, examination of urinary sediment, and analysis of urine measures (for example, fractional excretion of sodium in the absence of diuretics) can allow the early involvement of nephrologists and improve survival. Enteral rather than parenteral hyperalimentation in severely malnourished patients may improve survival. Sepsis causes 30% to 70% of deaths in patients with ATN; therefore, avoidance of intravenous lines, bladder catheters, and respirators is recommended. Because septic patients are vasodilated, large volumes of administered fluid accumulate in the lung interstitium of these patients. This condition necessitates ventilatory support, which when prolonged leads to acute respiratory distress syndrome, multiorgan failure, and increased mortality. More aggressive dialysis (for example, given daily) with biocompatible membranes may improve survival in some patients with acute renal failure.

CONCLUSIONS

New information about the importance of early diagnosis and supportive care for patients with ATN has emerged. However, randomized trials of these interventions are needed to test their effect on the morbidity and mortality of ATN.

The role of technetium-99m MAG3 renal imaging in the diagnosis of acute tubular necrosis of native kidneys

The differential diagnosis for patients with acute renal failure of their native kidneys, as a result of primary intrarenal disease, includes acute tubular necrosis, glomerulonephritis, and interstitial nephritis. The role of MAG3 renography has not been studied in this setting. The authors describe four patients with acute renal failure in whom MAG3 renal imaging reliably identified acute tubular necrosis, as confirmed by follow-up kidney biopsies. In contrast to the poor parenchymal uptake observed in glomerulonephritis and interstitial nephritis, MAG3 shows a distinctive pattern in patients with acute tubular necrosis. For patients with acute renal failure, a renal scan can facilitate decision-making regarding the initiation of therapy.

Acute cholestatic liver disease protects against glycerol-induced acute renal failure in the rat

BACKGROUND

It is widely held that liver disease predisposes toward acute tubular necrosis. The present study examines the effect of acute cholestatic liver disease on the susceptibility to glycerol-induced acute tubular necrosis in the rat.

METHODS

Acute cholestatic liver disease was induced by ligation of the common bile duct, while the intramuscular injection of hypertonic glycerol was used to induce acute tubular necrosis. Renal injury was assessed by plasma creatinine concentration and renal histology. An in vitro model of heme protein-induced renal injury (hemoglobin in conjunction with glutathione depletion) was employed to assess the cytoprotective effects of bilirubin.

RESULTS

Ligation of the common bile duct markedly reduced acute renal injury that occurs in the glycerol model (7.5 mL/kg body weight), as evidenced by a lower plasma creatinine concentration and less severe renal histologic injury. At a higher dose of glycerol (10 mL/kg body weight), ligation of the common bile duct again reduced renal injury and cumulative mortality that occurs five days after the induction of this model of acute renal failure. These protective effects of ligation of the common bile duct could not be ascribed to less severe muscle injury or red cell damage. Ligation of the common bile duct induced heme oxygenase-1 in the kidney and markedly so in the liver. Inhibition of heme oxygenase significantly attenuated, but did not prevent, the protective effects conferred by ligation of the common bile duct. Bilirubin, in low micromolar concentrations, was cytoprotective against heme protein-induced cell injury in vitro.

CONCLUSIONS

Ligation of the common bile duct confers resistance to glycerol-induced acute tubular necrosis in the rat, actions that arise, in part, from the induction of heme oxygenase-1 in the kidney and liver. Bilirubin, in micromolar concentrations, protects against heme protein-induced renal injury. Our studies uncover a novel form of acquired resistance to renal injury, occurring, unexpectedly, in the setting of acute cholestatic liver disease. We speculate that such potentially cytoprotective alterations may safeguard the kidney against irreversible functional and structural injury in the hepatorenal syndrome.

Treatment of complicated sarcoidosis with infliximab anti-tumor necrosis factor-alpha therapy

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) may have an important role in the clinical exacerbation of sarcoidosis.

OBJECTIVE

To treat sarcoidosis with infliximab, a chimeric human-murine anti-human TNF-alpha monoclonal antibody.

DESIGN

Case report.

SETTING

U.S. academic medical center.

PATIENT

A 72-year-old woman with sarcoidosis presenting with severe protein-losing enteropathy, hypoalbuminemia, and proximal myopathy who had not responded adequately to corticosteroid therapy and whose clinical course was further complicated by acute tubular necrosis and renal failure requiring long-term hemodialysis.

INTERVENTION

Intravenous infusion of infliximab, 5 mg/kg of ideal body weight; infusion was repeated at 2 and 6 weeks.

MEASUREMENTS

Clinical response of enteropathic and myopathic symptoms and serum albumin level.

RESULTS

Enteropathic and myopathic symptoms resolved after infliximab therapy, and the serum albumin level also improved. However, the clinical course was complicated by the development of a hypercoagulable state associated with circulating anticardiolipin antibodies, which prompted discontinuation of infliximab therapy.

CONCLUSIONS

Infliximab therapy was successful in a patient with sarcoidosis. Tumor necrosis factor-alpha may be an important mediator of clinical disease in sarcoidosis and could be an attractive target for therapeutic intervention. However, infliximab may cause adverse effects associated with cytokine cascade manipulation.

[Acute renal failure during severe malaria: physiopathology and therapeutic management. Apropos of 2 cases]

Renal failure secondary to acute tubular necrosis is a common complication of severe Plasmodium falciparum malaria. The purpose of this report is to describe two cases of severe malaria featuring acute renal failure observed in young patients who had failed to comply with chemoprophylaxis. Occurrence of renal failure was delayed four to seven days in relation to the beginning of the malaria attack. Hemodialysis was required in one case. Both patients were successfully treated by quinine perfusion. The main pathophysiology mechanisms underlying acute tubular necrosis are obstruction of capillaries and post-capillary venules by infected red blood cells and activation of monocytes that release cytokines such as tumor necrosis factor. Other nonspecific mechanisms may come into play including hypovolemia, release of catecholamines and subsequent activation of the rennin-angiotensin system, complement activation, and rhabdomyolysis. Acute tubular necrosis is the main renal complication of Plasmodium falciparum malaria but latent forms of acute glomerulonephritis have also been documented. Prognosis is usually favorable depending mainly on early diagnosis and prompt treatment.

Renal allograft rupture is associated with rejection or acute tubular necrosis, but not with renal vein thrombosis

BACKGROUND

Whereas rejection was reported to be the most common cause of renal allograft rupture (RAR) in the pre-cyclosporin era, renal vein thrombosis (RVT) is purported to be the main cause of RAR in patients taking cyclosporin. The extremely low incidence of RVT in our series (0.11%) prompted us to analyse our collective with regard to RAR.

METHOD

Between 1974 and 1999, 1811 renal transplants were performed. Patients with RAR, defined as a tear of the renal capsule and parenchyma, were identified and possible underlying factors studied.

RESULTS

RAR was diagnosed in nine male and five female recipients (0.8%) with a median age of 36 years. Immunosuppression consisted of azathioprine and prednisolone in seven patients and of cyclosporin-based therapy in the seven others. At exploration five grafts were removed immediately: three because of irreversible rejection, one because of deep wound infection, and one with a twisted renal vein. Six of the nine salvaged kidneys have been functioning after a mean observation time of 45 months. In the pre-cyclosporin era RAR was associated with acute rejection in five out of seven cases as compared with only three of the seven on cyclosporin treatment. Core biopsies might have been the cause in three cases.

CONCLUSION

RAR is a rare complication after renal transplantation. Acute rejection still represents the most frequent cause of RAR in the cyclosporin era.

[Lowered intrarenal protein degradation--an alternative path to glomerulosclerosis and tubulo-interstitial fibrosis]

Chronic renal failure is the consequence of progressive glomerulosclerosis and tubulo-interstitial fibrosis. The initiating hallmark of nephrosclerosis represents nephronal hypertrophy, due to an accumulation of proteins in the glomeruli and tubulointerstitium. From experimental and clinical investigations the conclusion can be drawn that the disturbed intrarenal protein balance with the consequent nephronal hypertrophy is at least partly the result of reduced protein degradation. Potential factors involved in impaired renal proteinase activities are cytokines like transforming growth factor beta 1 (TGF-beta 1), angiotensin II and advanced glycation endproducts (AGEs).

CONCLUSION

Nephrosclerosis as the common histological endpoint of chronic renal insufficiency is the result of an interaction between many pathogenetic factors. Its growing understanding implies the possibility of new therapeutic options to retard the progressive course of chronic renal failure.

Amelioration with vessel dilator of acute tubular necrosis and renal failure established for 2 days

Seventeen Sprague-Dawley rats had ischemic nonoliguric acute renal failure (ARF) induced by vascular clamping resulting in their preischemic blood urea nitrogen (BUN) and creatinine levels of 16 +/- 1 and 0.56 +/- 0.05 mg/dl to increase to 162 +/- 4 and 8.17 +/- 0.5 mg/dl, P < 0.001, respectively, at day 4 of postischemia. Vessel dilator, a 37-amino-acid cardiac peptide hormone (0.3 microg x kg(-1) x min(-1) ip), decreased the BUN and creatinine levels to 53 +/- 17 mg/dl and 0.98 +/- 0.12 mg/dl (P < 0.001) in another seven animals where ARF had been established for 2 days. Water excretion doubled with ARF and was further augmented by vessel dilator. Transthoracic echocardiography revealed left ventricular dilation as a probable cause of the increase in vessel dilator in the circulation with ARF, and vessel dilator infusion reversed this dilation. At day 6 of ARF, mortality decreased to 14% with vessel dilator from 88% without vessel dilator. Acute tubular necrosis was <5% in the vessel dilator-treated rats compared with 25% to >75% in the placebo-treated ARF animals. We conclude that vessel dilator improves acute tubular necrosis and renal function in established ARF.

Thin basement membrane disease and acute renal failure secondary to gross hematuria and tubular necrosis

A patient with thin basement membrane disease (TBMD), macroscopic hematuria, and acute renal failure is described. A renal biopsy showed massive occlusion of renal tubules by red blood cells and casts. This was accompanied by tubular cell damage consistent with acute tubular necrosis. The patient was receiving warfarin because of a history of deep venous thrombosis at the time he developed the acute renal failure. The possible relationship of the warfarin therapy to the TBMD, intratubular hemorrhage, and acute renal failure are discussed.

Acute tubular necrosis in patients with diabetes mellitus

We compared the clinical outcomes of patients with (n = 71) and without (n = 185) diabetes mellitus enrolled into the placebo arm of a large, multicenter clinical trial of patients with acute tubular necrosis (ATN). Compared with the nondiabetic patients, diabetic patients were older (65.5 +/- 12.9 versus 60.7 +/- 18.0 years, P < 0. 05), had higher usual serum creatinine concentration (1.7 +/- 0.6 versus 1.4 +/- 0.5 mg/dL, P < 0.001), and had a higher prevalence of underlying hypertension, coronary artery disease, and congestive heart failure (all P < 0.007). By day 21 after enrollment, neither mortality nor dialysis-free survival was different between the groups. Length of stay for surviving patients, in both the intensive care unit and the hospital, were significantly shorter for the diabetics. Among acute comorbidities predicting mortality or the need for dialysis, sepsis was more prevalent among the nondiabetic patients (18% versus 35%, diabetics versus nondiabetics, P < 0.05). In conclusion, clinical outcomes for diabetic patients with ATN were no worse than for nondiabetic patients, despite their older age and worse underlying renal function. Patients with diabetes mellitus had more chronic cardiovascular disease but were less acutely ill. We speculate that cardiovascular disease is a risk factor for ATN in patients with diabetes mellitus. These results fail to implicate the increasing prevalence of diabetes mellitus in the persistently poor prognosis of patients with ATN.

[A South American tapir (Tapirus terrestris) with peritonitis]

A 6-year-old male tapir was admitted because it had been anorexic for 1 day. On admission, the tapir weighed 160 kg. Its rectal temperature was 32.4 degrees C, its heart rate was 120 beats per minute, and its respiratory rate was 12 breaths per minute. The elasticity of the skin was diminished. Haematological evaluation upon admission revealed a haematocrit of 0.63 L.L-1., 6.0 G.L-1 leucocytes with 40 per cent band neutrophils. The concentrations of urea nitrogen and creatinine in plasma were raised (18.9 mmol L-1. and 475 mumol L-1., respectively). Severe combined acidosis was apparent; the venous pH was 6.965, the bicarbonate concentration was 13.7 mmol.L-1., and the venous pCO2 was 8.6 kPa. No strongyle eggs were isolated from faeces by flotation, but a faecal sample yielded a positive culture for Pseudomonas aeruginosa. Urinalysis revealed proteinuria and the presence of leucocytes and renal epithelial cells. Treatment with fluids, TMP/S (17.5 and 3.5 mg/kg body weight, twice a day, respectively), and clenbuterol (0.56 microgram/kg body weight, twice a day) intravenously was unsuccessful and the tapir died 4 days after hospitalization. At necropsy, peritonitis due to a colon infarct as well as chronic bronchopneumonia and renal tubulonecrosis were found. The antibiotic susceptibility of the bacteria isolated (Streptoc. sp., E. coli, and K. pneumoniae) from the tapir post-mortem was assessed.

Acute renal failure in the course of HIV infection: a single-institution retrospective study of ninety-two patients and sixty renal biopsies

BACKGROUND

Acute renal failure syndromes are frequently encountered in patients with human immunodeficiency virus (HIV) infection. Most reported cases of acute renal failure are related to acute tubular necrosis, but many other causes of renal failure have been described in these patients.

METHODS

The present work is a single-institution retrospective study of 92 HIV-infected patients with acute or rapidly progressing renal failure. In 60 cases, a renal biopsy was performed. For each patient we analysed clinical and pathological data, as well as the short-term prognosis.

RESULTS

Ten different causes of acute or rapidly progressing renal failure were documented: (i) haemolytic uraemic syndrome (32 patients); (ii) acute tubular necrosis either of ischaemic-toxic origin (18 patients) or due to rhabdomyolysis (six patients); (iii) obstructive renal failure which was either extrinsic (two patients), drug-induced (13 patients) or secondary to paraprotein precipitation (one patient); (iv) HIV-associated nephropathy (14 patients); (v) acute interstitial nephritis (two patients); (vi) various glomerulonephritis (four patients). In most cases, renal failure was severe (the mean creatinine clearance at entry was 12 ml/min). Most patients had a significant improvement in renal function with only symptomatic treatment. Eighteen per cent of the patients died within 2 months of the diagnosis of renal failure. Renal biopsy seems important for the diagnosis but also for the prognosis, at least in the cases of haemolytic-uraemic syndrome, HIV-associated nephropathy and drug-induced micro-obstructive renal failure.

CONCLUSION

Vascular and glomerular diseases are frequent causes of acute or rapidly progressing renal failure in HIV-infected patients. Renal biopsy appears to be safe and useful for the diagnosis and the prognosis of the renal failure. High mortality rate is only observed in patients with ischaemic/toxic causes of acute renal failure.

Cisplatin and hypomagnesemia

Hypomagnesemia is a well known side-effect in patients receiving cisplatin-containing chemotherapy. Cisplatin induces hypomagnesemia through its renal toxicity possibly by a direct injury to mechanisms of magnesium reabsorption in the ascending limb of the loop of Henle as well as the distal tubule. Since the magnesium reabsorption process still remains to be fully characterized, the effect by cisplatin on this process remains uncertain. Hypomagnesemia is a frequent complication to chemotherapy with cisplatin affecting up to 90% of patients if no corrective measures are initiated. The clinical importance of this hypomagnesemia remains uncertain. Possible symptoms of hypomagnesemia can be impossible to distinguish from symptoms related to the underlying disease or the treatment with chemotherapy. Existing studies on how to supplement magnesium during treatment with cisplatin have focused mainly on the effect on serum magnesium values and erythrocyte magnesium concentrations but both parameters are poor indicators of body magnesium stores. As long as the relationship between hypomagnesemia and possible complications thereof remains poorly elucidated, it seems reasonable to try to avoid hypomagnesemia. The best results seem to be provided by adding magnesium to the pre- and posthydration fluids.

Role of down-regulated CHIF mRNA in the pathophysiology of hyperkalemia of acute tubular necrosis

Acute tubular necrosis (ATN) is associated with hyperkalemia. We have shown that the medulla is the main site of impaired sodium (Na+)/potassium (K+) pump activity in ATN. CHIF, a gene that evokes K+ conductance in oocytes, is regulated in the colon by aldosterone and in the kidney by K+ intake. It is assumed that CHIF has a role in K+ homeostasis. To characterize the impaired K+ handling in ATN, the effect of impaired renal function on CHIF mRNA expression in the kidney and colon was studied. Three groups of rats with glycerol-induced ATN were studied: (1) control group, (2) moderate-ATN group, and (3) severe-ATN group. Serum creatinine levels in the control group were 45+/-2.1 micromol/L; in the moderate-ATN group, 224.8+/-16.9 micromol/L; and in the severe-ATN group, 376.5+/-15.9 micromol/L. In the group with severe ATN, significant hyperkalemia (P < 0.001 v control group) was noted. The expression of CHIF mRNA in relative units (percentage of control) in the moderate-ATN group, in the medulla, papilla, and colon, was 16.3%+/-5.6% (P < 0.001), 94.2%+/-9.3% (P=not significant ), and 165.9%+/-11.1% (P < 0.001); and in the severe-ATN group was 11.1%+/-6.4% (P < 0.001), 73.7%+/-4% (P < 0.001), and 310.8%+/-27.3% (P < 0.001), respectively. These results show that (1) in both moderate and severe ATN, CHIF mRNA is dramatically reduced in the medulla, (2) in severe ATN, CHIF mRNA expression decreases in the papilla, and (3) CHIF mRNA is upregulated in direct relationship to the severity of ATN and to the levels of aldosterone in the colon. These results suggest that the hyperkalemia that occurs in severe ATN stems at least in part from the downregulation of CHIF mRNA in the kidney medulla and papilla. The compensatory increase in colonic CHIF mRNA is not sufficient to maintain normal serum K+ levels.

The bioartificial renal tubule assist device to enhance CRRT in acute renal failure

Current therapy for acute tubular necrosis (ATN) continues to have an exceedingly high mortality rate, exceeding 50% even with dialytic or hemofiltrative support. Current renal replacement therapy in ATN only substitutes for filtration function of the kidney but not its cellular metabolic functions. Replacing these metabolic functions may optimize current therapy for this devastating disease process. In this regard, a renal tubule assist device (RAD) has been developed to be placed in an extracorporeal continuous hemoperfusion circuit in series with a hemofilter. The RAD consists of porcine renal proximal tubule cells grown as confluent monolayers of a multifiber bioreactor with a membrane surface area from 0.4 to 1.6 m2. The cells along the inner surface of the hollow fibers are immunoprotected from the patient's blood by the hollow fiber membrane. In preliminary experiments in uremic dogs, this device has been shown to tolerate a uremic environment while providing reabsorptive, metabolic, and endocrinologic activity. Pilot human trials of the RAD are anticipated within the next year to improve current renal replacement therapy in ATN.

Risk factors for vascular thrombosis in pediatric renal transplantation: a special report of the North American Pediatric Renal Transplant Cooperative Study

Vascular thrombosis remains a major cause of graft failure, accounting for 12.2% of failed index transplants and 19.2% of repeat transplants. We conducted a special study to identify the risk factors for vascular thrombosis. A total of 4394 transplants (2060 living donor [LD] transplants and 2334 cadaver donor [CAD] source transplants) were evaluated. The respective vascular thrombosis rates for LD and CAD transplants were 38/2060 (1.8%) and 100/2334 (4.2%) (P<0.001). Univariate analysis showed that the rate of graft loss due to thrombosis was significantly higher in younger children (less than 2 years of age) as compared with older age groups (2-5 years, 6-12 years, and more than 12 years of age) (9.0% vs. 5.5%, 4.4%, and 3.5% for CAD transplant recipients and 3.5% vs. 3.4%, 0.7%, and 1.9% for LD graft recipients). Recipients of kidneys from cadaver donors less than 5 years of age had a significantly higher thrombosis rate (8.3%) than did recipients from older donor groups (5-10 years, 4.5%; greater than 10 years, 3.2%). Recipients of kidneys with cold ischemia time greater than 24 hr also had a higher thrombosis rate (5.6%), as compared with recipients of kidneys with a shorter cold ischemia time (3.2%). Recipients of antilymphocyte therapy on day 0 or day 1 were at dimished risk of graft loss due to thrombosis (2.2% vs. 4.1%, P=0.001). Comparable trends were seen for both LD and CAD organ recipients. LD organ recipients with a history of prior transplantation had a significantly higher rate of thrombosis as compared with those who received a primary transplant (4.6% vs. 1.6%, P=0.005). For both LD and CAD organ recipients, the occurrence of acute tubular necrosis was a significnat risk factor for the development of thrombosis. Regression analysis showed that for LD organ recipients, a history of prior transplantation increased the risk for thrombosis, whereas increasing recipient age had a linear decreasing risk effect. The use of antilymphocyte antibody or cyclosporine on day 0/1 decreased the risk for thrombosis. For CAD kidney recipients, organ cold ischemia time greater than 24 hr increased the risk for thrombosis. The use of antibody induction therapy, donors greater than 5 years of age, and increasing recipient age were factors that decreased the risk for thrombosis.

Anaritide in acute tubular necrosis. Auriculin Anaritide Acute Renal Failure Study Group

BACKGROUND

Atrial natriuretic peptide, a hormone synthesized by the cardiac atria, increases the glomerular filtration rate by dilating afferent arterioles while constricting efferent arterioles. It has been shown to improve glomerular filtration, urinary output, and renal histopathology in laboratory animals with acute renal dysfunction. Anaritide is a 25-amino-acid synthetic form of atrial natriuretic peptide.

METHODS

We conducted a multicenter, randomized, double-blind, placebo-controlled clinical trial of anaritide in 504 critically ill patients with acute tubular necrosis. The patients received a 24-hour intravenous infusion of either anaritide (0.2 microgram per kilogram of body weight per minute) or placebo. The primary end point was dialysis-free survival for 21 days after treatment. Other end points included the need for dialysis, changes in the serum creatinine concentration, and mortality.

RESULTS

The rate of dialysis-free survival was 47 percent in the placebo group and 43 percent in the anaritide group (P = 0.35). In the prospectively defined subgroup of 120 patients with oliguria (urinary output, < 400 ml per day), dialysis-free survival was 8 percent in the placebo group (5 of 60 patients) and 27 percent in the anaritide group (16 of 60 patients, P = 0.008). Anaritide-treated patients with oliguria who no longer had oliguria after treatment benefited the most. Conversely, among the 378 patients without oliguria, dialysis-free survival was 59 percent in the placebo group (116 of 195 patients) and 48 percent in the anaritide group (88 of 183 patients, P = 0.03).

CONCLUSIONS

The administration of anaritide did not improve the overall rate of dialysis-free survival in critically ill patients with acute tubular necrosis. However, anaritide may improve dialysis-free survival in patients with oliguria and may worsen it in patients without oliguria who have acute tubular necrosis.