Acute renal failure from xanthine nephropathy during management of acute leukemia

Allopurinol use leading to xanthine nephrolithiasis in pediatric tumor lysis syndrome: a case series

Tumor lysis syndrome (TLS) is a life-threatening metabolic disorder caused by massive tumor lysis. Allopurinol, a xanthine oxidase inhibitor, is initiated during chemotherapy to prevent hyperuricemia and subsequent acute kidney injury (AKI). We report two cases of xanthine nephrolithiasis during TLS in newly diagnosed hematologic malignancy patients receiving prophylactic allopurinol. Allopurinol use likely promoted xanthine crystallization, stone formation, and AKI.

Use of rasburicase to improve kidney function in children with hyperuricemia and acute kidney injury

BACKGROUND

Hyperuricemia contributes to decrease in kidney function and induces additional renal damage in children with acute kidney injury (AKI). Rasburicase oxidizes uric acid (UA), decreasing its serum quantities in less than 24 h.

METHODS

This is a retrospective study involving hospitalized patients under 18 years of age with underlying pathology diagnosed with AKI and severe hyperuricemia treated with rasburicase over a 4-year period.

RESULTS

We describe 15 patients from 4 days of life to 18 years (median: 4.4 years). Seventy-three percent had known underlying pathologies. All presented worsening of basal renal function or AKI data. All received the usual medical treatment for AKI without response. Twenty percent received an extrarenal depuration technique. All had hyperuricemia with a mean (± SD) of 13.1 (± 2.19) mg/dl. After rasburicase administration UA levels fell to a mean (± SD) of 0.76 (± 0.62) mg/dl (p < 0.001) in less than 24 h. In parallel, a decrease in the mean plasma creatinine was observed (2.92 mg/dl to 1.93 mg/dl (p = 0.057)) together with a significant improvement of the mean glomerular filtration rate (16.3 ml/min/1.73 m2 to 78.6 ml/min/1.73 m2) (p = 0.001)). No side effects were recorded. Kidney function normalized in all cases or returned to baseline levels.

CONCLUSIONS

Although the use of rasburicase is not routinely approved in pediatric patients with severe hyperuricemia and AKI, it has been used successfully without complications, and helped prevent progressive kidney damage. This study could serve as a basis for suggesting the off-label use of rasburicase for the management of complex pediatric patients in whom UA plays an important role in the development of AKI.

Expert consensus guidelines for the prophylaxis and management of tumor lysis syndrome in the United States: Results of a modified Delphi panel

INTRODUCTION

Tumor lysis syndrome (TLS), which occurs spontaneously or in response to anticancer treatment, results in the release of intracellular potassium, phosphorus, and nucleic acids into the bloodstream, which results in secondary clinical complications that may be fatal. Prior TLS guidelines do not take into consideration potent novel oncologic agents or contemporary treatment paradigms with increased risk of TLS. Thus, a modified Delphi panel of experts was convened to provide an update for TLS management guidelines based upon a combination of supporting literature and practice consensus.

METHODS

A three-round modified Delphi process was implemented. For round 1, nine expert panelists completed a web-based questionnaire developed using published literature. In round 2, panelists were asked to reconsider their answers to questions that did not reach consensus (defined as ≥ 66% agreement among voting panelists). Round 3 was an unblinded, moderated virtual meeting to discuss any remaining questions that did not reach consensus.

RESULTS

Detailed recommendations are given for prophylaxis, monitoring, and management of TLS risks and complications, with hydration being a key element of TLS prophylaxis and management. Guidelines for the management of acute effects of TLS and prevention of long-term renal effects include management of hyperkalemia, hypocalcemia, hyperphosphatemia, and hyperuricemia.

DISCUSSION

Although the control of uric acid levels is quite effective with currently available agents, panelists emphasize the importance of monitoring and treating other dangerous electrolyte abnormalities such as hyperkalemia and hyperphosphatemia. Guidelines from this modified Delphi panel should aid clinicians in preventing and managing TLS.

Stabilization of uric acid mixed crystals by melamine

Melamine stabilizes heterogeneous nucleation of calcium crystals by increasing the retention time and decreasing the rate of dissolution. Stabilization of such mixed crystals limit the efficacy of non-invasive treatment options for kidney stones. Crystalline forms of uric acid (UA) are also involved in urolithiasis or UA kidney stones; however, its interactions with contaminating melamine and the resulting effects on the retention of kidney stones remain unknown. Since melamine augments calcium crystal formation, it provides an avenue for us to understand the stability of UA-calcium phosphate (CaP) crystals. We show here that melamine facilitates UA+CaP crystal formation, resulting in greater aggregates. Moreover, melamine induced mixed crystal retention through a time-dependent manner in presence and/or absence of hydroxycitrate (crystal inhibitor), indicating its abridged effectiveness as conventional remedy. CaP was also shown to modify optical properties of UA+CaP mixed crystals. Differential staining of individual crystals revealed enhanced co-aggregation of UA and CaP. The dissolution rate of UA in presence of melamine was faster than its heterogeneous crystallization form with CaP, although the size was comparatively much smaller, suggesting disparity in regulation between UA and CaP crystallization. While melamine stabilized UA, CaP and mixed crystals in relatively physiological conditions (artificial urine), the retentions of those crystals were further augmented by melamine, even in presence of hydroxycitrate, thus reducing treatment efficacy.

Urine Xanthine Crystals in Hematologic Malignancies with Tumor Lysis Syndrome

Tumor lysis syndrome (TLS) is a metabolic disorder caused by massive tumor lysis. Hypouricemic agents are administered to prevent TLS-related hyperuricemia and renal failure. We experienced three cases of urine xanthine crystals during TLS in patients with hematologic malignancies who received prophylactic febuxostat. Yellowish and pinkish deposits were observed in urinary tract catheters and urinary bags. Urine microscopy revealed that the deposits were xanthine crystals. In rapid tumor lysis, inhibition of xanthine oxidase can cause xanthine accumulation and urine xanthine crystallization. During TLS, urine xanthine crystals may be overlooked, so careful observation and management are required to avoid xanthine nephropathy.

Tumor Lysis Syndrome

Tumor lysis syndrome (TLS) is an oncologic emergency due to massive tumor cell lysis with the release of large amounts of potassium, phosphate, and nucleic acids into the systemic circulation. Clinical presentation is characterized by hyperkalemia, hyperphosphatemia, hyperuricemia, and hypocalcemia. Acute kidney injury due to tumor lysis is potentiated by the precipitation of uric acid and calcium phosphate as well as renal vasoconstriction. Early recognition of tumor lysis can help prevent cardiac arrhythmias, seizures, and death. Management includes intravenous hydration to maintain urine flow, medications targeting hyperuricemia including rasburicase and allopurinol and in severe cases renal replacement therapy may be required.

Excessive elevation of serum phosphate during tumor lysis syndrome: Lessons from a particularly challenging case

Burkitt’s lymphoma is a common cause of tumor lysis syndrome (TLS) and, in the era of aggressive utilization of prophylactic allopurinol and recombinant uricase enzyme, nephrologists are increasingly witnessing monovalent or divalent cation abnormalities without marked uric acid elevation. An 18-year-old male received his 1^st cycle of intensive chemotherapy for Burkitt’s lymphoma and developed TLS as defined by the Cairo Bishop criteria. Lactate dehydrogenase peaked at 9,105 U/L (range: 130 – 250) and was accompanied by acute kidney injury, including serum creatinine 2.2 mg/dL on the 4^th day with oliguria, hyperkalemia, extreme hyperphosphatemia (21.4 mg/dL), hypermagnesemia, and hypocalcemia. Renal replacement therapy decision was made based on life-threatening electrolyte disturbances. The competing necessity to effectively control hyperphosphatemia and avoid the complication of dialysis disequilibrium syndrome prompted us to perform an initial intermittent hemodialysis with simultaneous intravenous mannitol administration, followed by continuous hemodialysis to manage the continued production of phosphorus from cell lysis. Osmotic stability during the therapy session was affirmatively demonstrated (322, 319 mOsm/kg, respectively). The patient showed excellent tolerance for these therapies and eventually recovered renal function as demonstrated during follow-up visits.

Differential metabolomic signatures of declining renal function in Types 1 and 2 diabetes

BACKGROUND

Chronic kidney disease (CKD) shows different clinical features in Types1 (T1D) and 2 diabetes (T2D). Metabolomics have recently provided useful contribution to the identification of biomarkers of CKD progression in either form of the disease. However, no studies have so far compared plasma metabolomics between T1D and T2D in order to identify differential signatures of progression of estimated glomerular filtration rate (eGFR) decline.

METHODS

We used two large cohorts of T1D (from Finland) and T2D (from Italy) patients followed up to 7 and 3 years, respectively. In both groups, progression was defined as the top quartile of yearly decline in eGFR. Pooled data from the two groups were analysed by univariate and bivariate random forest (RF), and confirmed by bivariate partial least squares (PLS) analysis, the response variables being type of diabetes and eGFR progression.

RESULTS

In progressors, yearly eGFR loss was significantly larger in T2D [-5.3 (3.0), median (interquartile range)mL/min/1.73 m2/year] than T1D [-3.7 (3.1) mL/min/1.73 m2/year ; P = 0.018]. Out of several hundreds, bivariate RF extracted 22 metabolites associated with diabetes type (all higher in T1D than T2D except for 5-methylthioadenosine, pyruvate and β-hydroxypyruvate) and 13 molecules associated with eGFR progression (all higher in progressors than non-progressors except for sphyngomyelin). Three of the selected metabolites (histidylphenylalanine, leucylphenylalanine, tryptophylasparagine) showed a significant interaction between disease type and progression. Only eight metabolites were common to both bivariate RF and PLS.

CONCLUSIONS

Identification of metabolomic signatures of CKD progression is partially dependent on the statistical model. Dual analysis identified molecules specifically associated with progressive renal impairment in both T1D and T2D.

Prevention and Treatment of Tumor Lysis Syndrome in the Era of Onco-Nephrology Progress

Background: Tumor lysis syndrome (TLS) is an oncologic emergency due to a rapid break down of malignant cells usually induced by cytotoxic therapy, with hyperuricemia, hyperkalemia, hyperphosphatemia, hypocalcemia, and serious clinical consequences such as acute renal injury, cardiac arrhythmia, hypotension, and death. Rapidly expanding knowledge of cancer immune evasion mechanisms and host-tumor interactions has significantly changed our therapeutic strategies in hemato-oncology what resulted in the expanding spectrum of neoplasms with a risk of TLS. Summary: Since clinical TLS is a life-threatening condition, identifying patients with risk factors for TLS development and implementation of adequate preventive measures remains the most critical component of its medical management. In general, these consist of vigilant laboratory and clinical monitoring, vigorous IV hydration, urate-lowering therapy, avoidance of exogenous potassium, use of phosphate binders, and – in high-risk cases – considering cytoreduction before the start of the aggressive agent or a gradual escalation of its dose. Key Messages: In patients with a high risk of TLS, cytotoxic chemotherapy should be given in the facility with ready access to dialysis and a treatment plan discussed with the nephrology team. In the case of hyperkalemia, severe hyperphosphatemia or acidosis, and fluid overload unresponsive to diuretic therapy, the early renal replacement therapy (RRT) should be considered. One must remember that in TLS, the threshold for RRT initiation may be lower than in other clinical situations since the process of cell breakdown is ongoing, and rapid increases in serum electrolytes cannot be predicted.

Monodispersed gold nanoparticles entrapped in ordered mesoporous carbon/silica nanocomposites as xanthine oxidase mimic for electrochemical sensing of xanthine

Monodispersed Au nanoparticles in ordered mesoporous carbon/silica (Au/OMCS) nanocomposites were prepared by the solvent evaporation induced self-assembly. Au/OMCS nanocomposites were characterized through XRD, BET, and TEM. The obtained nanocomposites exhibit uniform mesopores with the size of 18 ± 2 nm. And ultrafine Au nanoparticles with the size of 3~7 nm are well dispersed in the cavities. An ultrasensitive nanoenzyme sensor was fabricated based on a Au/OMCS-modified electrode. The Au/OMCS-modified electrode displays high xanthine oxidase-like catalytic activity evaluated through cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The DPV response currents are linearly dependent on concentrations of xanthine (Xa) in the range 0.10-20 μM, along with a high sensitivity of 6.84 μA μM^-1 cm^-2 and very low detection limit of 0.006 μM (S/N = 3) under the optimal working potential of 0.64 V vs. SCE. Interference experiments show that the nanoenzyme sensor has no obvious responses to most potentially interfering species at a potential of 0.64 V. The fabricated sensor has been applied to the determination of Xa in spiked urine samples with recoveries ranging from 98.26 to 101.4%. Graphical abstract.

Diagnosis and management of tumor lysis syndrome

Tumor lysis syndrome (TLS) is an oncological emergency characterized by a classic tetrad of hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia. Risk assessment and prophylactic therapy is critical in preventing this oncological emergency. Treatment of established TLS involves aggressive hydration, electrolyte management, and the use of hypouricemic agents.

Tumor lysis syndrome in childhood malignancies

Background

Tumor lysis syndrome (TLS) is the most common life-threatening oncological emergency encountered by physicians treating children with lymphoproliferative malignancies. Healthcare providers should be aware of the condition in order to prevent occurrence and prompt timely management to avoid severe consequences.

Objective

To provide an update on the current understanding, evaluation, and management of tumor lysis syndrome in childhood malignancies.

Methods

A PubMed search was performed in Clinical Queries using the keywords ‘tumor lysis syndrome’ and ‘malignancies’ with Category limited to clinical trials and reviews for ages from birth to 18 years.

Results

There were 22 clinical trials and 37 reviews under the search criteria. TLS is characterized by acute electrolyte and metabolic disturbances resulting from massive and abrupt release of cellular contents into the circulation due to breakdown of tumor cells. If left untreated, it can lead to multiorgan compromise and eventually death. Apart from close monitoring and medical therapies, early recognition of risk factors for development of TLS is also necessary for successful management.

Conclusions

Prophylactic measures to patients at risk of TLS include aggressive fluid management and judicious use of diuretics and hypouricemic agents. Both allopurinol and urate oxidase are effective in reducing serum uric acid. Allopurinol should be used as prophylaxis in low-risk cases while urate oxidase should be used as treatment in intermediate to high-risk cases. There is no evidence on better drug of choice among different urate oxidases. The routine use of diuretics and urine alkalinization are not recommended. Correction of electrolytes and use of renal replacement therapy may also be required during treatment of TLS.

Drug-Induced Urolithiasis in Pediatric Patients

Drug-induced nephrolithiasis is a rare condition in children. The involved drugs may be divided into two different categories according to the mechanism involved in calculi formation. The first one includes poorly soluble drugs that favor the crystallization and calculi formation. The second category includes drugs that enhance calculi formation through their metabolic effects. The diagnosis of these specific calculi depends on a detailed medical history, associated comorbidities and the patient's history of drug consumption. There are several risk factors associated with drug-induced stones, such as high dose of consumed drugs and long duration of treatment. Moreover, there are some specific risk factors, including urinary pH and the amount of fluid consumed by children. There are limited data regarding pediatric lithogenic drugs, and hence, our aim was to perform a comprehensive review of the literature to summarize these drugs and identify the possible mechanisms involved in calculi formation and discuss the management and preventive measures for these calculi.

Current understanding of tumor lysis syndrome

Tumor lysis syndrome (TLS) is an oncologic emergency from the intracellular release of material in lysing malignant cells. The earlier it is treated, the less likely it is to be harmful to an individual and spread through the body. Common complications of TLS include arrhythmias, which are caused by hypocalcemia or hyperkalemia, renal failures due to hyperuricemia or hyperphosphatemia, and seizures. Furthermore, the risk to develop TLS varies widely based on several factors including factors that are related to disease, the patient, and the treatment of the patient. Laboratory data can be used to gauge the severity of TLS based on patient serum levels for specific markers. On the contrary, evidence of TLS via radiological imaging and electrocardiogram findings has been a limited way to evaluate TLS, indicating the need for further research in this area. Common trends of treatment have also been seen in the past several years, evident by case studies seen in the following literature review.

Tumor lysis syndrome following cabazitaxel administration for metastatic castration-resistant prostate cancer: A case report

Introduction

Tumor lysis syndrome is a rare and potentially fatal complication of oncological treatment. It is characterized by biochemical changes associated with the rapid lysis of malignant cells, usually after chemotherapy. Tumor lysis syndrome is typically noted in patients with hematological malignancies, and it rarely occurs in patients with solid tumors.

Case presentation

We report a case of tumor lysis syndrome after cabazitaxel administration for metastatic castration‐resistant prostate cancer. To our knowledge, tumor lysis syndrome after cabazitaxel therapy has not been reported previously. The patient was a 77‐year‐old man who developed clinical tumor lysis syndrome after a single dose of cabazitaxel for metastatic castration‐resistant prostate cancer. He was treated with hydration and the recombinant uricolytic agent rasburicase, and his condition improved.

Conclusion

It is extremely important to assess the risk factors for tumor lysis syndrome and to perform active prevention procedures in order to avoid fatal outcomes. It may be beneficial to use rasburicase in patients with established tumor lysis syndrome.

Febuxostat administration for the prevention of tumour lysis syndrome: A meta-analysis

WHAT IS KNOWN AND OBJECTIVE

Tumour lysis syndrome is an oncological emergency, characterized by rapid cytolysis leading to an abrupt rise of serum uric acid levels. The aim of the present meta-analysis is to evaluate the efficacy and safety of febuxostat as a preventive measure in patients at risk of tumour lysis syndrome development, by comparing it with allopurinol administration.

METHODS

MEDLINE, Scopus, Cochrane Central Register of Controlled Trials, Clinicaltrials.gov and Google Scholar databases were searched from inception to 15 December 2018. All studies evaluating the effectiveness of febuxostat in preventing tumour lysis syndrome were held eligible.

RESULTS AND DISCUSSION

Six studies were included with a total of 658 patients. Compared to allopurinol, febuxostat achieved a similar response rate (OR: 1.39, 95% CI: [0.55, 3.51]) and tumour lysis syndrome incidence (OR: 1.01, 95% CI: [0.56, 1.81]). Serum uric acid levels did not differ between the investigated groups at the second (MD: -0.21 mg/dL, 95% CI: [-1.30, 0.88]) and seventh (MD: -0.43 mg/dL, 95% CI: [-1.38, 0.51]) day of treatment. Elevation of liver function tests was the most common adverse effect, although its incidence was similar among patients treated with allopurinol and febuxostat.

WHAT IS NEW AND CONCLUSIONS

The present meta-analysis suggests that febuxostat may serve as an effective alternative to allopurinol in the prevention of tumour lysis syndrome. Future large-scale studies should define the optimal febuxostat dosage, explore the most appropriate population for its administration and better define its safety profile.

Update on the prevention and treatment of tumor lysis syndrome

Tumor lysis syndrome is a constellation of metabolic derangements seen when tumor cells die and release their intracellular contents into the systemic circulation. Hyperkalemia, hyperphosphatemia, hypocalcemia, and hyperuricemia may lead to severe organ dysfunction and even death. Tumor lysis syndrome is classically considered a complication of successful cancer treatment, but it can also occur in untreated malignancies characterized by rapid proliferation. In this review, we cover the types of cancers and chemo- and immunotherapies associated with tumor lysis syndrome, the mechanisms by which severe metabolic derangements can develop, and the available treatments.

Tumour lysis syndrome

Tumour lysis syndrome (TLS) is a life-threatening emergency characterised by a massive cytolysis with the release of intracellular electrolytes, nucleic acids, and metabolites into the circulation. TLS comprises laboratory derangements (hyperuricaemia, hyperkalaemia, hyperphosphataemia, and hypocalcaemia) responsible for acute kidney injury. In patients with hematologic malignancies after cytotoxic therapy or spontaneously and also in advanced solid tumours. Assessment of disease specific risk level for TLS in patients receiving anti-tumoural therapy is essential for early diagnosis. Prophylaxis is the mainstay of management of TLS. It is important to routinely initiate a risk-adapted prophylactic strategy to correct metabolic alterations and preserve renal function. High and intermediate risk patients and patients with established TLS should be managed with multidisciplinary medical care in a hospital unit to receive monitoring and medical care. Renal replacement therapy should be considered in patients with refractory TLS.

Tumor Lysis Syndrome

Tumor lysis syndrome (TLS) is an acute, life-threatening disease among adults and children that is associated with the initiation of cytoreductive therapy in the treatment of malignancy. A pattern of metabolic derangements occurs as a result of a massive release of intracellular contents into the systemic circulation. Characteristic findings include hyperuricemia, hyperphosphatemia, hyperkalemia, hypocalcemia, and uremia, all of which can lead to cardiac arrhythmia, seizures, renal failure, and sudden death. The incidence of TLS appears to be increasing because of a rapidly growing armamentarium of highly effective biologic and targeted therapies. Risk assessment and prevention are at the forefront of management and rely on clinician awareness, prophylactic measures, and vigilant laboratory monitoring. Established TLS requires early, aggressive intervention with intravenous hydration, electrolyte management, and the use of hypouricemic agents. This review highlights the central role of diagnostic laboratory criteria for TLS, and summarizes the clinical findings, pathophysiology, and evidence-based guidelines for the prevention and management of TLS.

Spontaneous tumor lysis syndrome in colon cancer: a case report and literature review

Although tumor lysis syndrome is well described, it is rarely seen or suspected in solid malignancies. Early recognition of this entity is paramount in reducing morbidity and mortality. Treating physicians should be aware of this possibility in solid tumor patients with either bulky disease or extensive liver involvement.

Tumor Lysis Syndrome in Patients with Hematological Malignancies

Tumor lysis syndrome is a metabolic complication that may follow the initiation of cancer therapy. It commonly occurs in hematological malignant patients particularly non-Hodgkin's lymphoma and acute leukemia due to chemotherapy or spontaneously. It is characterized by a biochemical abnormality such as hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia and its clinical outcome is directly related to these biochemical abnormalities. Prevention and treatment of tumor lysis syndrome depend on immediate recognition of patients at risk. Therefore, identifying patients at risk and prophylactic measures are important to minimize the clinical consequences of tumor lysis syndrome. Patients with low risk should receive hydration and allopurinol. On the other hand patients with high risk should receive hydration and rasburicase in an inpatient setting. It is important to start therapy immediately, to correct all parameters before cancer treatment, to assess risk level of patients for TLS, and to select treatment options based on the risk level. In this review a comprehensive search of literatures was performed using MEDLINE/PubMed, Hinari, the Cochrane library, and Google Scholar to summarize diagnostic criteria, incidence, predicting factors, prevention, and treatment options for tumor lysis syndrome in patients with hematological malignancies.

Pharmacokinetics, pharmacodynamics, and tolerability of LC350189, a novel xanthine oxidase inhibitor, in healthy subjects

Introduction

LC350189 is a novel selective xanthine oxidase inhibitor under clinical development for the management of hyperuricemia in gout patients. The aim of this study was to evaluate the pharmacokinetics, pharmacodynamics, and tolerability of the drug in healthy subjects.

Methods

A dose-block randomized, double-blind, active and placebo-controlled, single- and multiple-dosing study was conducted. A single ascending dose (SAD) study (10–600 mg) and a multiple ascending dose (MAD) study with once-daily doses (100–800 mg) for 7 days were conducted. Serial samples of blood and urine for pharmacokinetics/pharmacodynamics analysis were collected, and tolerability and adverse events were assessed throughout the study.

Results

Sixty-seven and 58 subjects were enrolled in the SAD and MAD studies, respectively. The mean C_max and AUC_last values increased with increasing doses, and exposure to LC350189 was dose proportional. The 24-hour mean serum uric acid (C_mean,24) decreased by 8.7%–31.7% (day 1) and 53.5%–91.2% (day 7) from baseline in the SAD and MAD studies, respectively, and the percentage decrease in C_mean,24 increased with higher doses.

Conclusion

LC350189 was well tolerated in the dose range of 10–800 mg. It lowered the serum and urine uric acid levels substantially in this dose range; the extent of the decrease in the serum uric acid level in the 200 mg dose group was similar or higher compared to that of febuxostat 80 mg group in the MAD study. It is expected that LC350189 could be safely administered once daily to patients with hyperuricemia or gout, leading to a sufficient decrease in uric acid levels.

Spontaneous Tumor Lysis Syndrome: A Case Report and Critical Evaluation of Current Diagnostic Criteria and Optimal Treatment Regimens

Tumor lysis syndrome (TLS) is a known complication of malignancy and its treatment. The incidence varies on malignancy type, but is most common with hematologic neoplasms during cytotoxic treatment. Spontaneous TLS is thought to be rare. This case study is of a 62-year-old female admitted with multisystem organ failure, with subsequent diagnosis of aggressive B cell lymphoma. On admission, laboratory abnormalities included renal failure, elevated uric acid (20.7 mg/dL), and 3+ amorphous urates on urinalysis. Oliguric renal failure persisted despite aggressive hydration and diuretic use, requiring initiation of hemodialysis prior to chemotherapy. Antihyperuricemic therapy and hemodialysis were used to resolve hyperuricemia. However, due to multisystem organ dysfunction syndrome with extremely poor prognosis, the patient ultimately expired in the setting of a terminal ventilator wean. Although our patient did not meet current TLS criteria, she required hemodialysis due to uric acid nephropathy, a complication of TLS. This poses the clinical question of whether adequate diagnostic criteria exist for spontaneous TLS and if the lack of currently accepted guidelines has resulted in the underestimation of its incidence. Allopurinol and rasburicase are commonly used for prevention and treatment of TLS. Although both drugs decrease uric acid levels, allopurinol mechanistically prevents formation of the substrate rasburicase acts to solubilize. These drugs were administered together in our patient, although no established guidelines recommend combined use. This raises the clinical question of whether combined therapy is truly beneficial or, conversely, detrimental to patient outcomes.

Tumor lysis syndrome in the emergency department: challenges and solutions

Tumor lysis syndrome (TLS) is the most common oncologic emergency. It is caused by rapid tumor cell destruction and the resulting nucleic acid degradation during or days after initiation of cytotoxic therapy. Also, a spontaneous form exists. The metabolic abnormalities associated with this syndrome include hyperkalemia, hyperphosphatemia, hypocalcemia, hyperuricemia, and acute kidney injury. These abnormalities can lead to life-threatening complications, such as heart rhythm abnormalities and neurologic manifestations. The emergency management of overt TLS involves proper fluid resuscitation with crystalloids in order to improve the intravascular volume and the urinary output and to increase the renal excretion of potassium, phosphorus, and uric acid. With this therapeutic strategy, prevention of calcium phosphate and uric acid crystal deposition within renal tubules is achieved. Other measures in the management of overt TLS are prescription of hypouricemic agents, renal replacement therapy, and correction of electrolyte imbalances. Hyperkalemia should be treated quickly and aggressively as its presence is the most hazardous acute complication that can cause sudden death from cardiac arrhythmias. Treatment of hypocalcemia is reserved for patients with electrocardiographic changes or symptoms of neuromuscular irritability. In patients who are refractory to medical management of electrolyte abnormalities or with severe cardiac and neurologic manifestations, early dialysis is recommended.

Development of tumor lysis syndrome (TLS): A potential risk factor in cancer patients receiving anticancer therapy

Tumor lysis syndrome (TLS) is characterized by hyperuricaemia, hyperphosphatemia, hyperkalaemia, as well as hypocalcaemia due to the breakdown of tumor cells undergoing cancer therapy (chemo/radio). Therefore it is of interest to evaluate oxidative stress using selective biological markers [Malondialdehyde (MDA), Superoxide Dismutase (SOD), Glutathione (GSH) and Catalase (CAT)] in TLS. We report the marked differences (statistically significant with control) observed among a selected set of biomarkers of oxidative stress (MDA = 8.66±1.37; SOD = 0.15±0.11; GSH = 2.25±.77; CAT = 0.76±.57) in TLS patients in addition to other conventional biomarkers. Moreover, correlation was investigated among the parameters of oxidative stress and other circulating biomarkers of TLS. Data suggest the use of SOD, MDA, and GSH as potential diagnostic biomarker for TLS with other biomarkers.

Tumor lysis syndrome: risk factors, diagnosis, and management

Tumor lysis syndrome (TLS) is a potentially fatal complication of induction therapy for several types of malignancies. Electrolyte derangements and even downstream complications may also occur prior to the initial presentation to a medical provider, before an oncologic diagnosis has been established. It is therefore imperative that emergency physicians be familiar with the risk factors for TLS in children as well as the criteria for diagnosis and the strategies for prevention and management. Careful evaluation of serum electrolytes, uric acid, and renal function must occur. Patients at risk for TLS and those who already exhibit laboratory or clinical evidence of TLS require close monitoring, aggressive hydration, and appropriate medical treatment.

Uric acid and the kidney

Uric acid, the end product of purine metabolism, is excreted predominantly by the proximal tubules. Abnormal serum levels of uric acid are due to alterations in production or excretion. Fractional excretion of uric acid is helpful in determining the underlying etiology of hypouricemia or hyperuricemia in children. Abnormalities in the molecular mechanisms that control renal uric acid tubular transport are implicated in various disorders associated with abnormal uric acid levels. Gout is rare in children; yet its presence necessitates evaluation for enzymatic defects in purine metabolism. Well-known effects of uric acid on the kidney include nephrolithiasis and acute kidney injury (AKI) in the setting of tumor lysis. However, recent data suggest that uric acid may be an important factor in the pathogenesis of AKI in general, as well as of chronic kidney disease (CKD) and hypertension. Hence, uric acid may not only be a marker but also a potential therapeutic target in kidney disease. Nonetheless, because of confounders, more studies are needed to clarify the association between uric acid and multifactorial disorders of the kidney.

Tumor lysis syndrome: new challenges and recent advances

Tumor lysis syndrome (TLS) is an oncologic emergency triggered by the rapid release of intracellular material from lysing malignant cells. Most common in rapidly growing hematologic malignancies, TLS has been reported in virtually every cancer type. Central to its pathogenesis is the rapid accumulation of uric acid derived from the breakdown of nucleic acids, which leads to kidney failure by various mechanisms. Kidney failure then limits the clearance of potassium, phosphorus, and uric acid leading to hyperkalemia, hyperphosphatemia, and secondary hypocalcemia, which can be fatal. Prevention of TLS may be more effective than treatment, and identification of at-risk individuals in whom to target preventative efforts remains a key research area. Herein, we discuss the pathophysiology, epidemiology, and treatment of TLS with an emphasis on the kidney manifestations of the disease.

Tumor lysis syndrome: a systematic review of case series and case reports

Tumor lysis syndrome (TLS) is a clinical condition that is caused by a massive lysis of tumor cells that accumulate very rapidly and disturb hemodynamics. This oncologic emergency requires immediate intervention. Tumor lysis syndrome was first described in the 19th century. Since then, it has become a well-known disease with improved management measures. Tumor lysis syndrome can occur after any type of neoplasm. It is highly associated with rapidly proliferating tumors compared with those that are well demarcated, such as acute lymphoblastic leukemia and high-grade non-Hodgkin lymphoma. Initiation of chemotherapy, radiotherapy, or steroid treatment may trigger TLS, or it may develop spontaneously. The release of massive quantities of intracellular contents may produce hyperkalemia, hyperphosphatemia, secondary hypocalcemia, hyperuricemia, and acute renal failure. Prevention and treatment measures include intravenous hydration, use of allopurinol and rasburicase, management of TLS-associated electrolyte abnormalities, and renal replacement therapy; the use of urine alkalinization remains controversial. In this article, we summarize the findings of case series and case reports published over the past 6 years in an effort to help familiarize clinicians better recognize and manage TLS.

Nephrocalcinosis and urolithiasis in children

The incidence of adult urolithiasis has increased significantly in industrialized countries over the past decades. Sound incidence rates are not available for children, nor are they known for nephrocalcinosis, which can appear as a single entity or together with urolithiasis. In contrast to the adult kidney stone patient, where environmental factors are the main cause, genetic and/or metabolic disorders are the main reason for childhood nephrocalcinosis and urolithiasis. While hypercalciuria is considered to be the most frequent risk factor, several other metabolic disorders such as hypocitraturia or hyperoxaluria, as well as a variety of renal tubular diseases, e.g., Dent's disease or renal tubular acidosis, have to be ruled out by urine and/or blood analysis. Associated symptoms such as growth retardation, intestinal absorption, or bone demineralization should be evaluated for diagnostic and therapeutic purposes. Preterm infants are a special risk population with a high incidence of nephrocalcinosis arising from immature kidney, medication, and hypocitraturia. In children, concise evaluation will reveal an underlying pathomechanism in >75% of patients. Early treatment reducing urinary saturation of the soluble by increasing fluid intake and by providing crystallization inhibitors, as well as disease-specific medication, are mandatory to prevent recurrent kidney stones and/or progressive nephrocalcinosis, and consequently deterioration of renal function.

Risk evaluation, prophylaxis, and treatment of tumor lysis syndrome: consensus of an Italian expert panel

INTRODUCTION

Tumor lysis syndrome (TLS) is a life-threatening complication in patients with hematological disease and/or solid tumors that results from rapid, large-scale tumor necrosis occurring spontaneously, or more commonly, as a result of chemotherapy. TLS is characterized by metabolic and electrolyte imbalances that include hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia. Identification of risk groups as well as early detection of TLS is crucial for the establishment of appropriate strategies of prophylaxis and treatment.

METHODS

A review of the peer-reviewed literature on TLS between 1990 and 2011 was conducted via a systematic search of the PubMed database using the keywords "TLS" [AND] "management," "risk evaluation," "prophylaxis," and "treatment." An expert opinion-based approach was used to review the national and international recommendations and guidelines on the topic.

RESULTS

The PubMed search produced 90 results, all of which were evaluated. These studies, together with a recent international consensus panel provided recommendations for evaluating the risk of TLS and providing prophylaxis. Five algorithms are presented that consider all of the factors when assessing the risk for neoplastic disease in general, and specifically for leukemia and lymphoma.

CONCLUSION

The present report provides clinicians with an easily consultable tool to guide the evidence-based management of this oncohematological emergency.

Recent advances in diagnosis and treatment of acute kidney injury in patients with cancer

Acute Kidney Injury (AKI) is a common complication in patients with cancer and even though there are many causes of renal failure in this population the classical classification of prerenal, renal, and postrenal is useful as a diagnostic guide. Important risk factors for AKI are dehydration, use of nephrotoxic drugs, preexisting renal impairment and large tumor burden. The development of AKI is associated with poor prognosis but early recognition and treatment initiation are associated with better outcomes in this population.

Uric Acid Nephrolithiasis: A Systemic Metabolic Disorder

Uric acid nephrolithiasis is characteristically a manifestation of a systemic metabolic disorder. It has a prevalence of about 10% among all stone formers, the third most common type of kidney stone in the industrialized world. Uric acid stones form primarily due to an unduly acid urine; less deciding factors are hyperuricosuria and a low urine volume. The vast majority of uric acid stone formers have the metabolic syndrome, and not infrequently, clinical gout is present as well. A universal finding is a low baseline urine pH plus insufficient production of urinary ammonium buffer. Persons with gastrointestinal disorders, in particular chronic diarrhea or ostomies, and patients with malignancies with a large tumor mass and high cell turnover comprise a less common but nevertheless important subset. Pure uric acid stones are radiolucent but well visualized on renal ultrasound. A 24 h urine collection for stone risk analysis provides essential insight into the pathophysiology of stone formation and may guide therapy. Management includes a liberal fluid intake and dietary modification. Potassium citrate to alkalinize the urine to a goal pH between 6 and 6.5 is essential, as undissociated uric acid deprotonates into its much more soluble urate form.

Rasburicase improves hyperuricemia in infants with acute kidney injury

Recent data suggest that elevated levels of uric acid (UA) might contribute to the progression of renal disease. Rasburicase, recombinant urate oxidase, is a highly safe and efficacious hypo-uricosuric agent for treatment of elevated UA levels from tumor lysis. We adopted the use of rasburicase for management of hyperuricemia in infants with acute kidney injury (AKI) and, herein, report our experience. We conducted a retrospective chart review of infants with hyperuricemia (UA > 8 mg/dl) secondary to AKI (serum creatinine > 1.5 mg/dl) treated with rasburicase. Seven infants (mean age 34 +/- 55 days, six male), with a mean weight of 3.2 +/- 1.2 kg, were identified. Rasburicase was administered intravenously as a single, onetime, bolus of 0.17 +/- 0.04 mg/kg body weight. Within 24 h, serum UA had decreased from 13.6 +/- 4.5 mg/dl to 0.9 +/- 0.6 mg/dl (P < 0.05), creatinine had decreased from 3.2 +/- 2.0 mg/dl to 2.0 +/- 1.2 mg/dl (P < 0.05), and urinary output had increased from 2.4 +/- 1.2 ml/kg per hour to 5.9 +/- 1.8 ml/kg per hour (P < 0.05). Continued improvements in UA, creatinine, and urinary output were observed in the week following administration of rasburicase, without rebound of the UA. We observed no treatment-related side effects. All patients demonstrated a normalization of uric acid level without need of renal replacement therapy. In conclusion, a single intravenously administered bolus of rasburicase appears to be a novel treatment for hyperuricemia in infants with AKI.

An integrated clinical approach for the identification, prevention, and treatment of tumor lysis syndrome

Tumor lysis syndrome (TLS) is a potentially life-threatening metabolic disorder that occurs when tumor cells undergo rapid decomposition spontaneously or in response to cytoreductive therapy. Delayed recognition of the metabolic imbalances caused by the massive release of tumor cell contents may result in clinical complications such as acute kidney injury, seizures, and cardiac arrhythmias. Prevention, the key principle in TLS management, relies on the identification of patients at risk for developing TLS during chemotherapy or because of disease progression. TLS-related risk factors pertain to tumor type (particularly hematologic malignancies), specific tumor characteristics (e.g. bulky tumor, high cellular proliferation rate, sensitivity to cytoreductive therapy), and other host-related factors. A comprehensive grading system proposed by Cairo and Bishop classifies TLS syndromes into laboratory or clinical TLS, thus facilitating TLS prevention and management. The mainstays of TLS management include monitoring of electrolyte abnormalities, vigorous hydration, prophylactic antihyperuricemic therapy with allopurinol, and rasburicase treatment of patients at high TLS risk or with established hyperuricemia. Urine alkalinization and use of diuretics remain controversial clinical practices. In this review, we describe the incidence of, risk factors for, and diagnostic characteristics of TLS and summarize strategies for the prevention and management of TLS-associated metabolic abnormalities, particularly hyperuricemia. We specifically highlight recently published TLS management guidelines, which focus on the prevention of TLS and hyperuricemia based on a patient's level of risk, and the important role of nephrologists in the prevention and treatment of one of the most serious complications of TLS, acute kidney injury.

Acute kidney injury in children

Acute kidney injury (AKI) (previously called acute renal failure) is characterized by a reversible increase in the blood concentration of creatinine and nitrogenous waste products and by the inability of the kidney to regulate fluid and electrolyte homeostasis appropriately. The incidence of AKI in children appears to be increasing, and the etiology of AKI over the past decades has shifted from primary renal disease to multifactorial causes, particularly in hospitalized children. Genetic factors may predispose some children to AKI. Renal injury can be divided into pre-renal failure, intrinsic renal disease including vascular insults, and obstructive uropathies. The pathophysiology of hypoxia/ischemia-induced AKI is not well understood, but significant progress in elucidating the cellular, biochemical and molecular events has been made over the past several years. The history, physical examination, and laboratory studies, including urinalysis and radiographic studies, can establish the likely cause(s) of AKI. Many interventions such as 'renal-dose dopamine' and diuretic therapy have been shown not to alter the course of AKI. The prognosis of AKI is highly dependent on the underlying etiology of the AKI. Children who have suffered AKI from any cause are at risk for late development of kidney disease several years after the initial insult. Therapeutic interventions in AKI have been largely disappointing, likely due to the complex nature of the pathophysiology of AKI, the fact that the serum creatinine concentration is an insensitive measure of kidney function, and because of co-morbid factors in treated patients. Improved understanding of the pathophysiology of AKI, early biomarkers of AKI, and better classification of AKI are needed for the development of successful therapeutic strategies for the treatment of AKI.

Asymptomatic kidney stones in long-term survivors of childhood acute lymphoblastic leukemia

We hypothesized an association between renal calculi and bone mineral density (BMD) deficits, shown in adults, exists in survivors of childhood acute lymphoblastic leukemia (ALL). Thus, we analyzed the associations between quantitative computed tomography (QCT)-determined renal calcifications and clinical parameters (gender, race, age at diagnosis and age at the time of QCT), BMD, treatment exposures and Tanner stage. We investigated the associations between stone formation and nutritional intake, serum and urinary calcium and creatinine levels, and urinary calcium/creatinine ratio. Exact chi(2)-test was used to compare categorical patient characteristics, and the Wilcoxon-Mann-Whitney test to compare continuous measurements. Of 424 participants, 218 (51.4%) were males; 371 (87.5%) were nonblack. Most (n=270; 63.7%) were >or=3.5 years at ALL diagnosis. Mean (s.d.) and median (range) BMD Z-scores of the entire cohort were -0.4 (1.2) and -0.5 (-3.9 to 5.1), respectively. Nineteen participants (10 males; 10 Caucasians) had kidney stones (observed prevalence of 4.5%; 19/424) with a significant negative association between stone formation and body habitus (body mass index, P=0.003). Stone formation was associated with treatment protocol (P=0.009) and treatment group (0.007). Thus, kidney stones in childhood ALL survivors could herald the future deterioration of renal function and development of hypertension. Long-term follow-up imaging may be warranted in these patients to monitor for progressive morbidity.

Gold salts, D-penicillamine and allopurinol

Gold salts have been used in the treatment of patients with rheumatoid arthritis since 1927 [1]. After a controlled study, the Empire Rheumatism Council [2], confirmed the effectiveness of gold salts for the treatment of rheumatoid arthritis. Even today, chrysotherapy has remained one of the major therapeutic modalities in the second line treatment of progressive rheumatoid arthritis. Gold salts are also used in the treatment of pemphigus vulgaris [3] and bronchial asthma [4]. Before the introduction of an orally administered gold compound, auranofin (triethylphosphine gold tetra-acetyl glycopyranoside), to clinical use [5-7], parenterally administered gold salts, such as sodium aurothiomalate and gold thioglucose comprised chrysotherapy. The frequency and severity of the side effects for patients treated with parenteral gold versus those given oral gold preparations are significantly different [8-10]. With introduction of newer parental DMARDs, toxicity has been reduced using combination therapy [10a, 10b].

Effective treatment and prophylaxis of hyperuricemia and impaired renal function in tumor lysis syndrome with low doses of rasburicase

BACKGROUND

Tumor lysis syndrome (TLS) is a complication that can cause renal failure by precipitation of uric acid (UA) and phosphate crystals in renal tubules. Rasburicase proved to be effective in rapidly reducing UA levels. Costs of rasburicase average up to 4500 euros. To assess if lower doses of rasburicase are effective, we treated patients with lower doses than recommended.

PATIENTS AND METHODS

Fifty patients received rasburicase for prophylaxis (n = 8) or treatment (n = 42) of TLS. The median age was 67 yr (16-88), 21 were female. The majority of patients (n = 46) had hematologic malignancies (acute leukemia, 14; lymphoma, 26; myeloproliferative/myelodysplastic syndromes, 6) and four had solid tumors. Creatinine levels were increased in 42 patients.

RESULTS

Baseline median UA and creatinine levels were 856.5 micromol/L (339-1659.5 micromol/L) and 192.7 micromol/L (65.4-761.1 micromol/L), respectively. Patients received between one and eight doses of rasburicase, the median total dose was 0.049 mg/kg. UA levels were lowered by 83%. After rasburicase treatment, median serum UA and creatinine levels were 160.6 micromol/L (5.9-779.2 micromol/L) and 111.4 micromol/L (46.9-610 micromol/L), respectively. Treatment costs were reduced by 96.8%.

CONCLUSIONS

Low doses of rasburicase are effective and cost-saving for prophylaxis and treatment of TLS. Application of an initial dose of 3-4.5 mg of rasburicase and subsequently dosage as needed, depending on UA levels, is feasible.