Immunolocalization of the calcium-sensing receptor in developing human kidney.

BACKGROUND: The calcium-sensing receptor (CSR) is a G-protein receptor that plays a critical role in calcium regulation. In the kidney, the CSR regulates calcium reabsorption in the thick ascending limb, where stimulation of the CSR inhibits calcium reabsorption in response to increased calcium in the peritubular fluid. In the collecting duct, apical CSR activation may play a role in osmoregulation, increasing water excretion in response to increased luminal calcium. METHODS: We studied the ontogeny of the CSR in developing human kidney using immunohistochemical methods. RESULTS: The CSR is first expressed in the S-shaped body in the region destined to form the ascending limb and distal tubule. Other regions of the S-shaped body, as well as ureteric buds, do not express the CSR. The CSR is observed in thick ascending limb as early as 20 wk of development. The CSR is not observed in proximal tubule or collecting duct between 20 and 40 wk of human development. CONCLUSION: During early human renal development, CSR expression is limited to the thick ascending limb and distal tubule, where this receptor may play a role in calcium homeostasis between 20 and 40 wk of human development.

Treatment of severe metformin-associated lactic acidosis with renal replacement therapy and tris-hydroxymethyl aminomethane: a case report.

BACKGROUND: Type B lactic acidosis is a rare but serious side effect of metformin use. The risk of metformin-associated lactic acidosis is elevated in renal or liver impairment, heart failure and in metformin overdose. Metformin-associated lactic acidosis is treated with renal replacement therapy although this can be limited by metformin's large volume of distribution and a patient's hemodynamic instability. Tris-hydroxymethyl aminomethane is a buffer that rapidly equilibrates in liver cells and increases the intracellular pH of hepatocytes. Intracellular alkalosis increases lactate uptake by the liver and can promote gluconeogenesis which results in increased lactate metabolism and decreased lactate production. Unlike intravenous bicarbonate which can worsen acidosis due to carbon dioxide retention and hypocalcemia, tris-hydroxymethyl aminomethane does not generate large amounts of carbon dioxide and can improve cardiac contractility in experimental models. CASE PRESENTATION: We present a case of a 43-year-old African American male who intentionally ingested 480,000 g of metformin. He developed severe metformin-associated lactic acidosis that was refractory to 21 hours of high flux hemodialysis. This was followed by an additional 12 hours of high flux hemodialysis augmented by continuous intravenous infusion of tris-hydroxymethyl aminomethane. After initiating tris-hydroxymethyl aminomethane, the patient had rapid reversal of lactic acidosis and was weaned off vasopressors and mechanical ventilation. CONCLUSIONS: While metformin-associated lactic acidosis can be treated with renal replacement therapy, severe cases of lactic acidosis may not be amenable to renal replacement therapy alone. Through its unique buffer mechanisms, tris-hydroxymethyl aminomethane can be used in conjunction with dialysis to rapidly improve acidosis associated with metformin.

Effect of dipyridamole plus aspirin on hemodialysis graft patency.

BACKGROUND: Arteriovenous graft stenosis leading to thrombosis is a major cause of complications in patients undergoing hemodialysis. Procedural interventions may restore patency but are costly. Although there is no proven pharmacologic therapy, dipyridamole may be promising because of its known vascular antiproliferative activity. METHODS: We conducted a randomized, double-blind, placebo-controlled trial of extended-release dipyridamole, at a dose of 200 mg, and aspirin, at a dose of 25 mg, given twice daily after the placement of a new arteriovenous graft until the primary outcome, loss of primary unassisted patency (i.e., patency without thrombosis or requirement for intervention), was reached. Secondary outcomes were cumulative graft failure and death. Primary and secondary outcomes were analyzed with the use of a Cox proportional-hazards regression with adjustment for prespecified covariates. RESULTS: At 13 centers in the United States, 649 patients were randomly assigned to receive dipyridamole plus aspirin (321 patients) or placebo (328 patients) over a period of 4.5 years, with 6 additional months of follow-up. The incidence of primary unassisted patency at 1 year was 23% (95% confidence interval [CI], 18 to 28) in the placebo group and 28% (95% CI, 23 to 34) in the dipyridamole-aspirin group, an absolute difference of 5 percentage points. Treatment with dipyridamole plus aspirin significantly prolonged the duration of primary unassisted patency (hazard ratio, 0.82; 95% CI, 0.68 to 0.98; P=0.03) and inhibited stenosis. The incidences of cumulative graft failure, death, the composite of graft failure or death, and serious adverse events (including bleeding) did not differ significantly between study groups. CONCLUSIONS: Treatment with dipyridamole plus aspirin had a significant but modest effect in reducing the risk of stenosis and improving the duration of primary unassisted patency of newly created grafts. (ClinicalTrials.gov number, NCT00067119.)

Use of aspirin associates with longer primary patency of hemodialysis grafts.

Extended-release dipyridamole plus low-dose aspirin (ERDP/ASA) prolongs primary unassisted graft patency of newly created hemodialysis arteriovenous grafts, but the individual contributions of each component are unknown. Here, we analyzed whether use of aspirin at baseline associated with primary unassisted graft patency among participants in a randomized trial that compared ERDP/ASA and placebo in newly created grafts. We used Cox proportional hazards regression, adjusting for prespecified baseline comorbidities and covariates. Of all participants, 43% reported use of aspirin at baseline; of these, 82% remained on nonstudy aspirin (i.e., excluding ERDP/ASA) at 1 year. After 1 year of follow-up, the incidence of primary unassisted patency among participants using aspirin at baseline was 30% (95% CI: 24 to 35%) and among those not using aspirin was 23% (95% CI: 18 to 27%). Use of aspirin at baseline associated with a dose-dependent prolongation of primary unassisted graft patency that approached statistical significance (adjusted HR, 0.83; 95% CI: 0.68 to 1.01; P=0.06). Use of aspirin at baseline did not associate with prolongation of cumulative graft patency or participant survival. In conclusion, use of aspirin associates with a trend toward longer primary unassisted patency of newly placed hemodialysis grafts similar to that observed for ERDP/ASA.

Decongestive treatment of acute decompensated heart failure: cardiorenal implications of ultrafiltration and diuretics.

In patients with acute decompensated heart failure (ADHF), treatment aimed at adequate decongestion of the volume overloaded state is essential. Despite diuretic therapy, many patients remain volume overloaded and symptomatic. In addition, adverse effects related to diuretic treatment are common, including worsening kidney function and electrolyte disturbances. The development of decreased kidney function during treatment affects the response to diuretic therapy and is associated with important clinical outcomes, including mortality. The occurrence of diuretic resistance and the morbidity and mortality associated with diuretic therapy has stimulated interest to develop effective and safe treatment strategies that maximize decongestion and minimize decreased kidney function. During the last few decades, extracorporeal ultrafiltration has been used to remove fluid from diuretic-refractory hypervolemic patients. Recent clinical studies using user-friendly machines have suggested that ultrafiltration may be highly effective for decongesting patients with ADHF. Many questions remain regarding the comparative impact of diuretics and ultrafiltration on important clinical outcomes and adverse effects, including decreased kidney function. This article serves as a summary of key clinical studies addressing these points. The overall goal is to assist practicing clinicians who are contemplating the use of ultrafiltration for a patient with ADHF.

Concomitant thrombotic thrombocytopenic purpura and ANCA-associated vasculitis in an adolescent.

Thrombotic thrombocytopenic purpura (TTP) rarely occurs with systemic vasculitis. A 17-year-old girl presented with non-bloody diarrhea, menorrhagia, and syncope. She had severe anemia (hemoglobin = 3.8 g/dl), thrombocytopenia (platelet = 7,000/mm(3)), and acute kidney injury (serum creatinine, Cr = 2.3 mg%). Peripheral smear examination confirmed the presence of microangiopathic hemolytic anemia. Additionally, she had a positive anti-nuclear antibody (1:1600) and normal complement levels. We considered the diagnosis of TTP, possibly associated with systemic lupus erythematosus, and promptly initiated pulse methylprednisolone and daily 3-4 l of plasma exchange therapy. Following resolution of her thrombocytopenia in 48 h, we performed a kidney biopsy that revealed diffuse proliferative, focal crescentic, and necrotizing glomerulonephritis with mild IgG immunofluorescence staining. Concomitantly, autoimmune work-up was significant for positive perinuclear anti-neutrophil cytoplasmic antibodies (p-ANCA = 1:640) and decreased von Willebrand factor cleaving protease activity (<5%). A final diagnosis of TTP with microscopic polyangiitis (p-ANCA-mediated) was made and treatment with daily oral cyclophosphamide and prednisone resolved her renal injury over 2 months (follow-up Cr = 1.0 mg%). Our case highlights the importance of identifying systemic disorders such as ANCA-associated vasculitis with TTP.

Brevundimonas vesicularis Peritonitis in a Chronic Peritoneal Dialysis Patient.

Gram-negative peritonitis in chronic peritoneal dialysis patients is difficult to treat and may result in catheter loss. Brevundimonas vesicularis is a Gram-negative rod bacterium which rarely causes infections in humans. A 41-year-old male receiving continuous cycling peritoneal dialysis for 5 months developed culture-negative peritonitis. He failed initial empiric treatment with intraperitoneal vancomycin and levofloxacin and thereafter intravenous gentamicin. B. vesicularis resistant to levofloxacin was isolated from the peritoneal fluid 21 days after his initial symptoms. Despite treatment with intravenous ceftriaxone and oral amoxicillin-clavulanate, the infection persisted, which required removal of the peritoneal catheter in order to cure this infection. We describe the features of B. vesicularis infection in our patient and the rarely reported additional cases.

Advancing Nephrology: Division Leaders Advise ASN.

New treatments, new understanding, and new approaches to translational research are transforming the outlook for patients with kidney diseases. A number of new initiatives dedicated to advancing the field of nephrology-from value-based care to prize competitions-will further improve outcomes of patients with kidney disease. Because of individual nephrologists and kidney organizations in the United States, such as the American Society of Nephrology, the National Kidney Foundation, and the Renal Physicians Association, and international nephrologists and organizations, such as the International Society of Nephrology and the European Renal Association-European Dialysis and Transplant Association, we are beginning to gain traction to invigorate nephrology to meet the pandemic of global kidney diseases. Recognizing the timeliness of this opportunity, the American Society of Nephrology convened a Division Chief Retreat in Dallas, Texas, in June 2019 to address five key issues: (1) asserting the value of nephrology to the health system; (2) productivity and compensation; (3) financial support of faculty's and divisions' educational efforts; (4) faculty recruitment, retention, diversity, and inclusion; and (5) ensuring that fellowship programs prepare trainees to provide high-value nephrology care and enhance attraction of trainees to nephrology. Herein, we highlight the outcomes of these discussions and recommendations to the American Society of Nephrology.

Immuno-localization of CD44 and osteopontin in developing human kidney.

CD44 is observed in ureteric bud structures and is implicated in branching morphogenesis during early mouse renal development. Healthy adult kidney demonstrates minimal CD44, but CD44 is up-regulated in renal diseases. CD44 may mediate binding of calcium oxalate crystals to tubular epithelia via the ligands osteopontin (OPN) and hyaluronan. Because 15% of premature infants develop nephrocalcinosis, developmental tubular CD44 expression might promote nephrocalcinosis. We studied CD44 and OPN immuno-localization in developing human kidney by immunohistochemical analysis. Human renal tissue between 18 and 40 wk of gestation showed CD44 immuno-localization in ureteric buds, with staining decreasing with increasing gestational age; CD44 was rarely observed in developing renal tubules. OPN was diffusely observed in proximal tubules, rarely observed in distal tubules, ureteric buds or metanephric structures. These data support the role of CD44 in early human nephron formation and branching morphogenesis. Rare CD44 staining in developing tubular epithelium suggests no role for CD44 in promoting calcium oxalate adherence to tubular epithelia in premature infants. Immuno-localization of OPN in tubules supports its role in tubular differentiation, but OPN does not seem to be necessary during early nephron formation.

Recognition and management of chronic kidney disease in an elderly ambulatory population.

BACKGROUND: Chronic kidney disease (CKD) is a growing problem among the elderly. Early detection is considered essential to ensure proper treatment and to avoid drug toxicity, but detection is challenging because elderly patients with CKD often have normal serum creatinine levels. We hypothesized that most cases of CKD in the elderly would go undetected, resulting in inappropriate prescribing. OBJECTIVE: To determine whether recognition of CKD is associated with more appropriate treatment DESIGN: Retrospective chart review PARTICIPANTS: All patients aged >/=65 years with a measured serum creatinine in the past 3 years at 2 inner city academic health centers. MEASUREMENTS: Estimated glomerular filtration rate (eGFR) calculated using the Modified Diet in Renal Disease equation, and for patients with eGFR < 60, documentation of CKD by the provider, diagnostic testing, nephrology referral and prescription of appropriate or contraindicated medications. RESULTS: Of 814 patients with sufficient information to estimate eGFR, 192 (33%) had moderate (eGFR < 60 mL/min) and 5% had severe (eGFR < 30 mL/min) CKD. Providers identified 38% of moderate and 87% of severe CKD. Compared to patients without recognized CKD, recognized patients were more likely to receive an ACE/ARB (80% vs 61%, p = .001), a nephrology referral (58% vs 2%, p < .0001), or urine testing (75% vs 47%, p < .0001), and less likely to receive contraindicated medications (26% vs 40%, p = .013). CONCLUSIONS: Physicians frequently fail to diagnose CKD in the elderly, leading to inappropriate treatment. Efforts should focus on helping physicians better identify patients with low GFR.

Effect of clopidogrel on early failure of arteriovenous fistulas for hemodialysis: a randomized controlled trial.

CONTEXT: The arteriovenous fistula is the preferred type of vascular access for hemodialysis because of lower thrombosis and infection rates and lower health care expenditures compared with synthetic grafts or central venous catheters. Early failure of fistulas due to thrombosis or inadequate maturation is a barrier to increasing the prevalence of fistulas among patients treated with hemodialysis. Small, inconclusive trials have suggested that antiplatelet agents may reduce thrombosis of new fistulas. OBJECTIVE: To determine whether clopidogrel reduces early failure of hemodialysis fistulas. DESIGN, SETTING, AND PARTICIPANTS: Randomized, double-blind, placebo-controlled trial conducted at 9 US centers composed of academic and community nephrology practices in 2003-2007. Eight hundred seventy-seven participants with end-stage renal disease or advanced chronic kidney disease were followed up until 150 to 180 days after fistula creation or 30 days after initiation of dialysis, whichever occurred later. INTERVENTION: Participants were randomly assigned to receive clopidogrel (300-mg loading dose followed by daily dose of 75 mg; n = 441) or placebo (n = 436) for 6 weeks starting within 1 day after fistula creation. MAIN OUTCOME MEASURES: The primary outcome was fistula thrombosis, determined by physical examination at 6 weeks. The secondary outcome was failure of the fistula to become suitable for dialysis. Suitability was defined as use of the fistula at a dialysis machine blood pump rate of 300 mL/min or more during 8 of 12 dialysis sessions. RESULTS: Enrollment was stopped after 877 participants were randomized based on a stopping rule for intervention efficacy. Fistula thrombosis occurred in 53 (12.2%) participants assigned to clopidogrel compared with 84 (19.5%) participants assigned to placebo (relative risk, 0.63; 95% confidence interval, 0.46-0.97; P = .018). Failure to attain suitability for dialysis did not differ between the clopidogrel and placebo groups (61.8% vs 59.5%, respectively; relative risk, 1.05; 95% confidence interval, 0.94-1.17; P = .40). CONCLUSION: Clopidogrel reduces the frequency of early thrombosis of new arteriovenous fistulas but does not increase the proportion of fistulas that become suitable for dialysis. Trial Registration clinicaltrials.gov Identifier: NCT00067119.

Nephrolithiasis and Nephrocalcinosis From Topiramate Therapy in Children With Epilepsy.

INTRODUCTION: Adults treated with topiramate may develop nephrolithiasis, but its frequency in children on topiramate is unknown. Topiramate inhibits renal carbonic anhydrase, which can lead to renal tubular acidosis and hypercalciuria. We studied 40 consecutive children who initiated topiramate therapy for seizures between January 1997 and February 2003, followed for a mean of 36 months. METHODS: Serum electrolytes, urinary calcium/creatinine ratios, and renal ultrasonography were performed before topiramate and every 6 months thereafter. RESULTS: Four children developed nephrolithiasis and/or nephrocalcinosis, which resolved on discontinuation of topiramate. In 40 patients, the mean urinary calcium/creatinine ratio increased over time (P < 0.001). The mean serum bicarbonate in 40 patients decreased over time (P < 0.01). Twenty-three children had urinary calcium/creatinine ratios before topiramate. Nine children with baseline hypercalciuria (defined as urinary calcium/creatinine >0.21) were compared with the 14 children with baseline normal urinary calcium excretion. A greater increase in urinary calcium/creatinine ratios occurred in hypercalciuric children (P < 0.001) and a greater decrease in serum bicarbonate levels occurred in the hypercalciuric children (P < 0.05) compared with children with baseline normal calcium excretion. Greater urinary calcium excretion was associated with increasing doses of topiramate (P = 0.039). CONCLUSION: Our study shows that long-term therapy with topiramate in children is associated with persistent hypercalciuria and metabolic acidosis, which can lead to nephrocalcinosis and/or nephrolithiasis. All children initiating topiramate therapy should have baseline and follow-up urinary calcium/creatinine studies, serum electrolytes, and periodic renal ultrasonography, if the urinary calcium/creatinine ratio increases to a level above normal for age.

Effect of Transient and Sustained Acute Kidney Injury on Readmissions in Acute Decompensated Heart Failure.

Although acute kidney injury (AKI) is common in heart failure, yet the impact of the onset, timing, and duration of AKI on short-term outcomes is not well studied. AKI was defined as an increase in serum creatinine SCr of ≥0.3 mg/dl or 1.5 times relative to the admission and further categorized as transient AKI (T-AKI: SCr returning to within 10% of baseline); sustained AKI (S-AKI: those with at least 72 hours of hospital stay and did not meet T-AKI); and unknown duration AKI (U-AKI: those with less than 72 hours stay and did not meet T-AKI). Reference category was no AKI (stable or <0.3 mg/dl change in SCr). The main outcome was 30-day all-cause hospital readmission. Unadjusted and adjusted association between AKI category of interest and main outcome was represented as percent and relative risks with 95% CIs. Statistical significance was set at an alpha of 0.05. From the Cerner Health Facts sample, 14,017 of 22,059 available subjects met the eligibility criteria. Approximately, 19.2% of our sample met the primary outcome. Compared with no AKI (readmission rate of 17.7%; 95% CI 16.4% to 18.9%), the adjusted rate of readmission was highest in patients with S-AKI (22.8%, 95% CI 20.8% to 24.8%; p <0.001), followed by 20.2% (95% CI 17.5% to 22.8%; p = 0.05) in T-AKI patients. Compared with no AKI, the adjusted relative risk of 30-day readmission was 1.29 (95% CI 1.17 to 1.42), 1.14 (95% CI 1.00 to 1.31), and 1.12 (95% CI, 1.01 to 1.26) in S-AKI, T-AKI, and U-AKI, respectively. In conclusion, both sustained AKI and patients with transient elevation still remain at a higher risk of readmission within 30 days. Future studies should focus on examining process-of-care after discharge in patients with different patterns of AKI.

Type 3 renal tubular acidosis associated with growth hormone deficiency.

BACKGROUND: We identified two boys with type 3 renal tubular acidosis (RTA) and growth hormone deficiency and we sought to differentiate them from children with classic type 1 distal RTA. METHODS: We reviewed all children <6 years of age with RTA referred over a 13-year period and compared the growth response to alkali therapy in these two boys and in 28 children with only type 1 distal RTA. RESULTS: All children with type 1 RTA reached the 5th percentile or higher on CDC growth charts within 2 years of alkali therapy. Their mean height standard deviation score (SDS) improved from -1.4 to -0.6 SDS and their mean mid-parental height (MPH) SDS improved from -0.6 to 0 SDS after 2 years. In contrast, the boys with growth hormone deficiency had a height SDS of -1.4 and -2.4 SDS after 2 years of alkali and the MPH SDS were both -2.6 SDS after 2 years of alkali therapy. Growth hormone therapy accelerated their growth to normal levels and led to long-term correction of RTA. CONCLUSIONS: A child with type 1 RTA whose height response after 2 years of alkali therapy is inadequate should undergo provocative growth hormone testing.

Effects of prolonged ethanol lock exposure to carbothane- and silicone-based hemodialysis catheters: a 26-week study.

PURPOSE: Antibiotic locks in catheter-dependent chronic hemodialysis patients reduce the rate of catheter-related bloodstream infections (CRBSIs), but may be associated with the development of resistant bacteria. Ethanol-based catheter locks may provide a better alternative; however, there are limited data on the long-term integrity of dialysis catheters exposed to ethanol. METHODS: We performed in vitro testing of two types of hemodialysis catheters­silicone (SLC) and carbothane (CBT) based­with a 70% ethanol lock (EL) versus heparin lock (HL) for 26 weeks. Lock solutions were changed thrice weekly to mimic a conventional hemodialysis schedule. We tested mechanical properties of the catheters at 0, 13 and 26 weeks by examining stress/strain relationships (SS400%) and modulus of elasticity (ME). Electron microscopy was performed to examine catheter ultrastructure at 0 and 26 weeks. RESULTS: Catheter integrity for HL versus EL in SLC (SS400%: 4.5 vs. 4.5 MPa, p = NS; ME: 4.6 vs. 4.7 MPa, p = NS) or CBT-based catheters (SS400%: 7.6 vs. 8.9 MPa, p = NS; ME: 9.6 vs. 12.2 MPa, p = NS) were all similar at 13 and 26 weeks. Scanning electron microscopy revealed no structural changes in the central and luminal wall internal surfaces of EL- versus HL-treated catheters. CONCLUSIONS: There were no significant differences in catheter integrity between SLC or CBT catheters exposed to a 70% EL for 26 weeks. Given its low cost, potential to avoid antibiotic resistance and structural integrity after 6 months of high-dose ethanol, ELs should be studied prospectively against antibiotic locks to assess the efficacy and safety in hemodialysis patients.

The role of circulating immune complexes and biocompatibility of staphylococcal protein A immunoadsorption in mitomycin C-induced hemolytic uremic syndrome.

Mitomycin-induced hemolytic uremic syndrome (HUS) is a life-threatening complication of this therapy, and increased levels of circulating immune complexes and hypocomplementemia have been found in some patients. We further characterize the role of immune complexes in mitomycin-HUS by showing that removal of these complexes by immunoadsorption with staphylococcal protein A columns correlates with temporal improvement in the microangiopathic hemolytic anemia in this disorder. Two immune complexes bound to the protein A column were identified: an 11S platelet-aggregating protein and a 15S non-platelet-aggregating protein. In addition, the patient had anaphylactoid reactions at the onset of immunoadsorption similar to first-use dialysis reactions that correlated with increases in complement 3a and 5a, interleukin-1 (IL-1), IL-6, and tumor necrosis factor levels. This case suggests that platelet-aggregating and complement-fixing circulating immune complexes are, in part, a proximate cause for mitomycin C-induced HUS. Therapy for mitomycin (HUS) with protein A columns should continue until circulating immune complexes reach undetectable levels and serum complement levels return to the normal range.

Outcome and complications of intraoperative hemodialysis during cardiopulmonary bypass with potassium-rich cardioplegia.

BACKGROUND: Potassium-rich cardioplegia has advantages over other cardioplegic solutions in preserving the myocardium during cardiopulmonary bypass, but it is avoided in patients with renal failure because of hyperkalemia. METHODS: We first determined the ability of intraoperative hemodialysis (IHD) to remove potassium during cardiopulmonary bypass with potassium-rich cardioplegia in 9 patients by measuring potassium levels in all dialysate and urine. We then studied 24 patients with renal failure, grouped with the 9 previous patients, to assess safety, rebound hyperkalemia, and patient outcome with this technique. RESULTS: In the first phase, 9 patients were administered 128 +/- 11 mmol of potassium in potassium-rich cardioplegia, and IHD removed 157 +/- 23 mmol. Urinary potassium excretion was only 10 +/- 3 mmol. Potassium removal occurred at a rate of 1.25 mmol/min with 0-mEq/L (mmol/L) potassium dialysate and a rate of 0.75 mmol/min with 3.0-mEq/L (mmol/L) potassium dialysate. In all 33 patients, successful initiation of cardiac rhythm occurred after cardiopulmonary bypass, and 5 patients had cardiac arrhythmias possibly from hypokalemia. In the next 24 hours, 5 dialysis-dependent patients developed hyperkalemia (potassium > 5.2 mEq/L [mmol/L]) requiring hemodialysis. Postoperative hemodialysis was delayed 2 to 3 days in the other patients. The overall death rate was 24% at 30 days. CONCLUSION: IHD effectively and safely removes potassium administered during potassium-rich cardioplegia during cardiopulmonary bypass in patients with renal failure and prevents postoperative hyperkalemia in the majority of patients. Overall mortality in patients with acute and chronic renal failure undergoing cardiac surgery is high irrespective of control of potassium balance in these patients.