Treating potassium disturbances: kill the killers but avoid overkill.

OBJECTIVES: In this publication, we review the definitions, symptoms, causes, differential diagnoses and therapies of hypokalemia and hyperkalemia. METHODS: Comprehensive tables and diagnostic algorithms are provided when appropriate. RESULTS AND CONCLUSIONS: Although both hypokalemia and hyperkalemia may be life-threatening, this is essentially the case with severe changes (serum potassium < 2.5 or > 6.5 mmol/L), the presence of symptoms or electrocardiographic deviations, the association with aggravating factors (e.g. digitalis intake) and/or rapid acute changes. Only these truly need an emergency therapeutic approach. In all other cases, a careful consideration of the causes and their correction should prevail over additional approaches to modify serum potassium concentration. Although most therapeutic approaches to both hypokalemia and hyperkalemia have been well established since many years, recently two new intestinal potassium binders have been introduced on the market. It remains to be elucidated whether these drugs truly have an additional role on top of the existing treatments.

European Renal Best Practice Guideline on kidney donor and recipient evaluation and perioperative care

The European Best Practice Guideline group (EBPG) issued guidelines on the evaluation and selection of kidney donor and kidney transplant candidates, as well as post-transplant recipient care, in the year 2000 and 2002. The new European Renal Best Practice board decided in 2009 that these guidelines needed updating. In order to avoid duplication of efforts with kidney disease improving global outcomes, which published in 2009 clinical practice guidelines on the post-transplant care of kidney transplant recipients, we did not address these issues in the present guidelines.The guideline was developed following a rigorous methodological approach: (i) identification of clinical questions, (ii) prioritization of questions, (iii) systematic literature review and critical appraisal of available evidence and (iv) formulation of recommendations and grading according to Grades of Recommendation Assessment, Development, and Evaluation (GRADE). The strength of each recommendation is rated 1 or 2, with 1 being a 'We recommend' statement, and 2 being a 'We suggest' statement. In addition, each statement is assigned an overall grade for the quality of evidence: A (high), B (moderate), C (low) or D (very low). The guideline makes recommendations for the evaluation of the kidney transplant candidate as well as the potential deceased and living donor, the immunological work-up of kidney donors and recipients and perioperative recipient care.All together, the work group issued 112 statements. There were 51 (45%) recommendations graded '1', 18 (16%) were graded '2' and 43 (38%) statements were not graded. There were 0 (0%) recommendations graded '1A', 15 (13%) were '1B', 19 (17%) '1C' and 17 (15%) '1D'. None (0%) were graded '2A', 1 (0.9%) was '2B', 8 (7%) were '2C' and 9 (8%) '2D'. Limitations of the evidence, especially the lack of definitive clinical outcome trials, are discussed and suggestions are provided for future research.We present here the complete recommendations about the evaluation of the kidney transplant candidate as well as the potential deceased and living donor, the immunological work-up of kidney donors and recipients and the perioperative recipient care. We hope that this document will help caregivers to improve the quality of care they deliver to patients. The full version with methods, rationale and references is published in Nephrol Dial Transplant (2013) 28: i1-i71; doi: 10.1093/ndt/gft218 and can be downloaded freely from http://www.oxfordjournals.org/our_journals/ndt/era_edta.html.

Development and validation of an ultra-high performance liquid chromatography-tandem mass spectrometry method to measure creatinine in human urine.

Despite decades of creatinine measurement in biological fluids using a large variety of analytical methods, an accurate determination of this compound remains challenging. Especially with the novel trend to assess biomarkers on large sample sets preserved in biobanks, a simple and fast method that could cope with both a high sample throughput and a low volume of sample is still of interest. In answer to these challenges, a fast and accurate ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed to measure creatinine in small volumes of human urine. In this method, urine samples are simply diluted with a basic mobile phase and injected directly under positive electrospray ionization (ESI) conditions, without further purification steps. The combination of an important diluting factor (10(4) times) due to the use of a very sensitive triple quadrupole mass spectrometer (XEVO TQ) and the addition of creatinine-d3 as internal standard completely eliminates matrix effects coming from the urine. The method was validated in-house in 2012 according to the EMA guideline on bioanalytical method validation using Certified Reference samples from the German External Quality Assessment Scheme (G-Equas) proficiency test. All obtained results for accuracy and recovery are within the authorized tolerance ranges defined by G-Equas. The method is linear between 0 and 5 g/L, with LOD and LOQ of 5 × 10(-3) g/L and 10(-2) g/L, respectively. The repeatability (CV(r) = 1.03-2.07%) and intra-laboratory reproducibility (CV(RW) = 1.97-2.40%) satisfy the EMA 2012 guideline. The validated method was firstly applied to perform the German G-Equas proficiency test rounds 51 and 53, in 2013 and 2014, respectively. The obtained results were again all within the accepted tolerance ranges and very close to the reference values defined by the organizers of the proficiency test scheme, demonstrating an excellent accuracy of the developed method. The method was finally applied to measure the creatinine concentration in 210 urine samples, coming from 190 patients with a chronic kidney disease (CKD) and 20 healthy subjects. The obtained creatinine concentrations (ranging from 0.12 g/L up to 3.84 g/L) were compared, by means of a Passing Bablok regression, with the creatinine contents obtained for the same samples measured using a traditional compensated Jaffé method. The UHPLC-MS/MS method described in this paper can be used to normalize the concentration of biomarkers in urine for the extent of dilution.

The paradox of bardoxolone methyl: a call for every witness on the stand?

People with type 2 diabetes and chronic kidney disease (CKD) remain an extremely vulnerable population with increased cardiovascular morbidity, mortality and mounting societal costs. As such, any effort to improve their dismal outcome is heavily supported. Yet, most drugs fail to replicate the promising signals of early experiments in humans in large and methodologically sound trials. As a recent example, an independent data and safety committee advised the termination of a phase 3 trial due to excessive cardiovascular disease and especially heart failure in patients allocated to the antioxidant synthetic triterpenoid bardoxolone methyl versus placebo. We evaluate the reasons why this outcome in hindsight was possibly not totally unexpected and develop a mechanistic model that shows that the consistent drop in serum magnesium concentration in patients exposed to bardoxolone methyl might have contributed to the development of heart failure. As such, this trial, despite its negative outcome, might provide additional pieces of the puzzle enabling us to get a better grip on diseases that share increased inflammation and oxidative stress, such as type 2 diabetes, metabolic syndrome, heart failure and CKD.

AKI in early sepsis is a continuum from transient AKI without tubular damage over transient AKI with minor tubular damage to intrinsic AKI with severe tubular damage.

PURPOSE: The pathophysiology of septic acute kidney injury (AKI) is incompletely understood, and there is controversy on the role of renal hypoperfusion in early sepsis. We hypothesized that renal hypoperfusion plays a role in early sepsis and that there is a continuum between transient AKI without tubular damage, transient AKI with minor tubular damage, and intrinsic AKI. METHODS: A total of 107 consecutive patients with sepsis were included. Fractional excretion of sodium (FENa), urinary, and serum neutrophil gelatinase-associated lipocalin were measured at admission (T0) and 4 h (T4) and 24 h later (T24). Patients were classified according to FENa quartiles (FENaQ). Transient and intrinsic AKI were respectively defined as AKI that did or did not recover to no AKI in the following 5 days. RESULTS: A total of 57 developed transient AKI, 22 developed intrinsic AKI, and 28 did not have AKI. Of the ten patients with transient AKI classified in the two lowest FENa quartiles (FENa < 0.36 %) and without signs of local tubular damage, seven still did not show signs of tubular damage 24 h later. Also, 50 % of patients with intrinsic AKI classified in the same FENaQ did not show signs of local tubular damage at admission but did so 24 h later. CONCLUSIONS: There is a continuum between transient AKI without tubular damage, transient AKI with minor tubular damage, and intrinsic AKI in sepsis. Renal hypoperfusion seems to be the instigator for the development of AKI in the majority of patients with early sepsis. Other mechanisms in some patients cannot be excluded.

Safety and sample adequacy of renal transplant surveillance biopsies.

PURPOSE: To report on the safety and adequacy of surveillance biopsy for detecting subclinical lesions in clinically stable renal grafts. MATERIALS AND METHODS: We established an in-patient surveillance biopsy program with the elective performance of a renal transplant biopsy during the first year after renal transplantation. All biopsies in our centre were performed or supervised by the same operator. Patients were admitted to the hospital the day of biopsy and were discharged after 24h of observation. All patients were biopsied in supine position, using a 16-gauge needle with a spring-loaded gun (Bard) under real-time ultrasound guidance. Complication rates were retrospectively scored using the patients' charts and blood counts before and after biopsy. Major complications were defined as those requiring an intervention for resolution, a transfusion of blood products or an invasive procedure (angiography or surgery), and those that led to acute renal obstruction or failure, septicaemia, graft loss or death. In all other cases complications were considered minor. An adequate biopsy was defined as the presence of 7 or more glomeruli and at least one artery in the biopsy specimen. RESULTS: We performed 282 surveillance biopsies in 248 patients between January 2006 and December 2011. None of the complications were major. We observed 6% minor complications (n = 17). 5.6% (n = 16) of the complications were related to bleeding, with macroscopic haematuria as the most common condition (n = 10; 3.5%), followed by pain (n = 6; 2.1%) eighter due to a perinephric hematoma (n = 5) or a subcutaneous hematoma (n = 1). The biopsies contained a median number of 9 glomeruli (range 0-39) with 70% of biopsies containing at least 7 glomeruli and one artery. CONCLUSION: The procedure for taking surveillance biopsies was proven to be safe. There were no major complications and only rare minor complications. The majority of the samples were adequate for histological examination.

Review of protein-bound toxins, possibility for blood purification therapy.

Protein-bound uremic retention solutes, i.e. phenolic compounds, such as p-cresylsulfate, and indolic compounds, such as indoxyl sulfate, have been intensively studied in recent years and have been shown to be associated especially with cardiovascular toxicity and adverse outcomes in chronic kidney disease. In this review, we will focus on their toxicity and their removal by dialysis strategies, which is hampered due to their protein binding. Hemodiafiltration slightly improves the removal of protein-bound solutes as compared to hemodialysis, although the clinical benefit on outcomes still needs to be demonstrated. Removal by means of absorption and interference with intestinal generation or renal tubular excretion are interesting alternative strategies under investigation.

Questioning the Pathogenic Role of the GLA p.Ala143Thr "Mutation" in Fabry Disease: Implications for Screening Studies and ERT.

Fabry disease is an X-linked inborn error of glycosphingolipid metabolism caused by quantitative or qualitative defects in the lysosomal enzyme alfa-Galactosidase A (aGAL A), ultimately resulting in vital organ dysfunction. Mainly the kidneys, the heart, and the central nervous system are involved. While the classical phenotype of Fabry disease is readily recognizable, screening studies have identified clinical variants. Here, we report the phenotype associated with the GLA p.Ala143Thr (c.427G>A) mutation in 12 patients aged 42-83 years. None of the patients had classical Fabry signs or symptoms as angiokeratoma, hypohidrosis, acroparesthesia, or cornea verticillata. Possible Fabry manifestations were renal failure (5/12), stroke (7/12), and left ventricular hypertrophy (5/12), but these were not necessarily attributable to the p.Ala143Thr mutation, as a cardiac biopsy in one female and left ventricular hypertrophy and kidney biopsies in two males with renal failure and microalbuminuria lacked Gb-3 deposits. The literature data on this mutation as well as data collected in the Fabry Outcome Survey (FOS) database confirm these findings. The association of renal failure, stroke, and left ventricular hypertrophy with this mutation could be the result of selection bias, as most patients were detected in screening studies.We conclude that care should be taken with attribution of vital organ dysfunction to GLA sequence alterations. In case of the p.Ala143Thr mutation, and possibly also other mutations associated with an attenuated phenotype, diagnostic tools such as biopsy and imaging should critically evaluate the relation of end-organ failure with Fabry disease, as this has important consequences for enzyme replacement therapy.

An update on uremic toxins.

In the last decade, uremic toxicity as a potential cause for the excess of cardiovascular disease and mortality observed in chronic kidney disease gained more and more interest. This review focuses on uremic toxins with known cardiovascular effects and their removal. For protein-bound solutes, for example, indoxylsulfate and the conjugates of p-cresol, and for small water-soluble solutes, for example, guanidines, such as ADMA and SDMA, there is a growing evidence for a role in cardiovascular toxicity in vitro (e.g., affecting leukocyte, endothelial, vascular smooth muscle cell function) and/or in vivo. Several middle molecules (e.g., beta-2-microglobulin, interleukin-6, TNF-alpha and FGF-23) were shown to be predictors for cardiovascular disease and/or mortality. Most of these solutes, however, are difficult to remove during dialysis, which is traditionally assessed by studying the removal of urea, which can be considered as a relatively inert uremic retention solute. However, even the effective removal of other small water-soluble toxins than urea can be hampered by their larger distribution volumes. Middle molecules (beta-2-microglobulin as prototype, but not necessarily representative for others) are cleared more efficiently when the pore size of the dialyzer membrane increases, convection is applied and dialysis time is prolonged. Only adding convection to diffusion improves the removal of protein-bound toxins. Therefore, alternative removal strategies, such as intestinal adsorption, drugs interfering with toxic biochemical pathways or decreasing toxin concentration, and extracorporeal plasma adsorption, as well as kinetic behavior during dialysis need further investigation. Even more importantly, randomized clinical studies are required to demonstrate a survival advantage through these strategies.

Uremic toxins inhibit renal metabolic capacity through interference with glucuronidation and mitochondrial respiration.

During chronic kidney disease (CKD), drug metabolism is affected leading to changes in drug disposition. Furthermore, there is a progressive accumulation of uremic retention solutes due to impaired renal clearance. Here, we investigated whether uremic toxins can influence the metabolic functionality of human conditionally immortalized renal proximal tubule epithelial cells (ciPTEC) with the focus on UDP-glucuronosyltransferases (UGTs) and mitochondrial activity. Our results showed that ciPTEC express a wide variety of metabolic enzymes, including UGTs. These enzymes were functionally active as demonstrated by the glucuronidation of 7-hydroxycoumarin (7-OHC; K(m) of 12±2µM and a V(max) of 76±3pmol/min/mg) and p-cresol (K(m) of 33±13µM and a V(max) of 266±25pmol/min/mg). Furthermore, a wide variety of uremic toxins, including indole-3-acetic acid, indoxyl sulfate, phenylacetic acid and kynurenic acid, reduced 7-OHC glucuronidation with more than 30% as compared with controls (p<0.05), whereas UGT1A and UGT2B protein expressions remained unaltered. In addition, our results showed that several uremic toxins inhibited mitochondrial succinate dehydrogenase (i.e. complex II) activity with more than 20% as compared with controls (p<0.05). Moreover, indole-3-acetic acid decreased the reserve capacity of the electron transport system with 18% (p<0.03). In conclusion, this study shows that multiple uremic toxins inhibit UGT activity and mitochondrial activity in ciPTEC, thereby affecting the metabolic capacity of the kidney during CKD. This may have a significant impact on drug and uremic retention solute disposition in CKD patients.

Cinacalcet for managing secondary hyperparathyroidism in dialysis patients in clinical practice in Belgium: a 16-month observational study (ECHO-B).

In Belgium, the calcimimetic cinacalcet is initially reimbursed for < or = 4 months in dialysis patients with secondary hyperparathyroidism (SHPT) and intact parathyroid hormone (iPTH) > or = 800 pg/mL, or iPTH 300-800 pg/ mL and Ca x P > 55 mg 2/dL2 despite > or = 6 months' optimal treatment with vitamin D sterols and/or phosphate binders. The Belgian, multicentre, observational study ECHO-B evaluated cinacalcet in such patients. Patients who began cinacalcet treatment after March 1, 2007 were eligible. Data were collected retro/prospectively from 6 months before until 16 months after starting cinacalcet (whether or not cinacalcet was continued). Median iPTH was markedly elevated (816 [IQR 551-991] pg/mL) at baseline (the time of starting cinacalcet), but decreased continuously over the course of the study, reaching a value of 414 pg/mL (IQR 240-641; median change -41%) at 4 months, 335 pg/mL (IQR 159-616; -60%) at 12 months and 250 pg/mL (IQR 172-436; -64%) at 16 months. Reductions in serum calcium (-7%) and phosphorus (-13%) were already (near) maximal at 4 months. The primary outcome (iPTH 150-300 pg/mL and/or a > or = 30% reduction within 4 months of starting cinacalcet; criterion for continued reimbursement in Belgium) was achieved in 65/81 patients (80%; 95% CI 72-89%). Results show that in dialysis patients with SHPT in real-life clinical practice, mineral metabolism improves after starting cinacalcet: our study findings suggest that PTH levels may continue decreasing after 12 months' treatment in this setting.

Kidney transplantation in emerging countries: do we know all issues?

Although it seems that end stage renal disease (ESRD) therapies gradually become more accessible in the developing world, yet, the vast majority of people living in those areas do not have access to dialysis and especially transplantation because of the economic and technological inequality as compared with the developed world. Despite the great advantage in survival and considerable socioeconomic advantages of transplantation vs. dialysis, there is a widespread recognition that the growing gap between organ supply and demand will continue into the foreseeable future. Several reasons might be considered in this regard as: insufficient data on the topic in the public domain, inadequate governmental financial resources, lack of public awareness, education and motivation for organ donation as well as the low number of organized teams of transplant surgeons and nephrologists, and lack of organizational infrastructure, i.e. coordinators. The defined priorities for the future in terms of improving living donor transplantation, composition of the official waiting lists and registries of transplant recipients and living donors and the role of transplant professionals have been discussed. In conclusion, whatever the governmental support is, as professionals, we should just reinforce our efforts to help our patients as best as we can in the current situation.

Chitinase-like proteins are candidate biomarkers for sepsis-induced acute kidney injury.

Sepsis-induced acute kidney injury (AKI) is a frequent complication of critically ill patients and leads to high mortality rates. The specificity of currently available urinary biomarkers for AKI in the context of sepsis is questioned. This study aimed to discover urinary biomarkers for septic AKI by contemporary shotgun proteomics in a mouse model for sepsis and to validate these in individual urine samples of mice and human septic patients with and without AKI. At 48 h after uterine ligation and inoculation of Escherichia coli, aged mice (48 weeks) became septic. A subgroup developed AKI, defined by serum creatinine, blood urea nitrogen, and renal histology. Separate pools of urine from septic mice with and without AKI mice were collected during 12 h before and between 36-48 h after infection, and their proteome compositions were quantitatively compared. Candidate biomarkers were validated by Western blot analysis of urine, plasma, and renal tissue homogenates from individual mice, and a limited number of urine samples from human septic patients with and without AKI. Urinary neutrophil gelatinase-associated lipocalin, thioredoxin, gelsolin, chitinase 3-like protein 1 and -3 (CHI3L3) and acidic mammalian chitinase were the most distinctive candidate biomarkers selected for septic AKI. Both neutrophil gelatinase-associated lipocalin and thioredoxin were detected in urine of septic mice and increased with severity of AKI. Acidic mammalian chitinase was only present in urine of septic mice with AKI. Both urinary chitinase 3-like protein 1 and -3 were only detected in septic mice with severe AKI. The human homologue chitinase 3-like protein 1 was found to be more excreted in urine from septic patients with AKI than without. In summary, urinary chitinase 3-like protein 1 and -3 and acidic mammalian chitinase discriminated sepsis from sepsis-induced AKI in mice. Further studies of human chitinase proteins are likely to lead to additional insights in septic AKI.

When the earth trembles in the Americas: the experience of Haiti and Chile 2010.

The response of the nephrological community to the Haiti and Chile earthquakes which occurred in the first months of 2010 is described. In Haiti, renal support was organized by the Renal Disaster Relief Task Force (RDRTF) of the International Society of Nephrology (ISN) in close collaboration with Médecins Sans Frontières (MSF), and covered both patients with acute kidney injury (AKI) and patients with chronic kidney disease (CKD). The majority of AKI patients (19/27) suffered from crush syndrome and recovered their kidney function. The remaining 8 patients with AKI showed acute-to-chronic renal failure with very low recovery rates. The intervention of the RDRTF-ISN involved 25 volunteers of 9 nationalities, lasted exactly 2 months, and was characterized by major organizational difficulties and problems to create awareness among other rescue teams regarding the availability of dialysis possibilities. Part of the Haitian patients with AKI reached the Dominican Republic (DR) and received their therapy there. The nephrological community in the DR was able to cope with this extra patient load. In both Haiti and the DR, dialysis treatment was able to be prevented in at least 40 patients by screening and adequate fluid administration. Since laboratory facilities were destroyed in Port-au-Prince and were thus lacking during the first weeks of the intervention, the use from the very beginning on of a point-of-care device (i-STAT®) was very efficient for the detection of aberrant kidney function and electrolyte parameters. In Chile, nephrological problems were essentially related to difficulties delivering dialysis treatment to CKD patients, due to the damage to several units. This necessitated the reallocation of patients and the adaptation of their schedules. The problems could be handled by the local nephrologists. These observations illustrate that local and international preparedness might be life-saving if renal problems occur in earthquake circumstances.

Immediate posttransplantation cotrimoxazole-induced immune thrombocytopenia.

Drug-induced immune thrombocytopenia (DITP) can be caused by numerous drugs. When this condition develops, platelet destruction results from binding of antibodies to normal platelets only in the presence of a sensitizing drug. A recently proposed model suggests that these drug-dependent antibodies are derived from a pool of naturally occurring antibodies with weak affinity for specific epitopes on certain platelet membrane glycoproteins. We describe here a case of DITP secondary to cotrimoxazole exposure in the immediate posttransplantation phase in a renal transplant recipient. Apart from heparin-induced thrombocytopenia, DITP posttransplantation has to the best of our knowledge never been described, perhaps because of its immune-mediated origin. Our case demonstrates that DITP can occur posttransplantation, that cotrimoxazole due to its intensive use in the transplanted population is one of the most likely causative agents and that a timely recognition and treatment might have important consequences for both graft and patient.