Hyponatraemia diagnosis and treatment clinical practice guidelines

Hyponatremia, defined as a serum sodium concentration <135mmol/l, is the most common water-electrolyte imbalance encountered in clinical practice. It can lead to a wide spectrum of clinical symptoms, from mild to severe or even life threatening, and is associated with increased mortality, morbidity and length of hospital stay. Despite this, the management of hyponatremia patients remains problematic. The prevalence of hyponatremia in a wide variety of conditions and the fact that hyponatremia is managed by clinicians with a broad variety of backgrounds have fostered diverse institution- and specialty-based approaches to diagnosis and treatment. To obtain a common and holistic view, the European Society of Intensive Care Medicine (ESICM), the European Society of Endocrinology (ESE) and the European Renal Association-European Dialysis and Transplant Association (ERA-EDTA), represented by European Renal Best Practice (ERBP), have developed clinical practice guidelines on the diagnostic approach and treatment of hyponatremia as a joint venture of 3societies representing specialists with a natural interest in hyponatremia. In addition to a rigorous approach to the methodology and evaluation of the evidence, the document focuses on patient-positive outcomes and on providing a useful tool for clinicians involved in everyday practice. In this article, we present an abridged version of the recommendations and suggestions for the diagnosis and treatment of hyponatremia extracted from the full guide.

2012 ERA-EDTA Registry Annual Report: cautious optimism on outcomes, concern about persistent inequalities and data black-outs

The 2012 ERA-EDTA Registry Annual Report contains both good news and bad news. On the bright side, the 2-year survival of patients starting renal replacement therapy (RRT) for chronic kidney disease (CKD), on dialysis or receiving a living-related kidney transplantation, has progressively increased to 82.2, 79.7 and 98.3%, respectively, whereas for cadaveric kidney transplantation it remains stable (96.0-96.1%). On the dark side, inequalities persist between European citizens in access to renal transplantation and in incidence and prevalence of RRT. Living in Greece, Belgium (French- or Dutch-speaking) or Portugal (the GBP countries) is associated with higher chances of initiating RRT than living in other European countries. The adjusted RRT incidence for GBP countries was 188, 201-174 and 220* (* unadjusted) pmp in 2012, respectively (versus 122, 114 and 97 pmp in the Netherlands or two Spanish regions bordering Portugal). In lower income countries, a low RRT incidence may represent lack of access to needed healthcare (e.g. Montenegro 26 pmp). However, how can the high incidence and prevalence of RRT in the GBP countries be explained? Do GBP citizens have access to RRT that is denied, rejected or considered unnecessary in other high income countries? Does the GBP healthcare system fail to prevent progression of CKD? Do local genetic or environmental factors favour CKD progression? Unravelling the underlying reasons is an urgent research need: only an understanding of the causes will allow correction of the problem. Unavailability of data from some large countries (e.g. Germany and Italy) is not helpful.

Individualization of dialysate calcium concentration according to baseline pre-dialysis serum calcium

BACKGROUND

A positive calcium balance may contribute to vascular calcification, while a negative balance increases iPTH. We explored the impact of different dialysate calcium concentrations on bone and mineral metabolism parameters according to pre-dialysis serum calcium levels.

RESULTS

Fifty-six hemodialysis patients were dialyzed with 3.0 or 2.5 mEq/l dialysate [calcium] in a crossover study of two weeks. Bone mineral metabolites were measured prior to and following the hemodialysis session. A 3.0 mEq/l dialysate [calcium] increased more post-dialysis total calcium and ionized calcium than 2.5 mEq/l dialysate [calcium]. The mildest dialysis-induced changes in calcium and PTH were observed in patients with pre-dialysis serum calcium <8.75 mg/dl dialyzed with 2.5 mEq/l dialysate [calcium] and in patients with pre-dialysis serum calcium >9.15 mg/dl dialyzed with 3.0 mEq/l calcium dialysate.

CONCLUSION

In conclusion, the individualization of dialysate calcium concentration according to baseline pre-dialysis serum calcium may prevent major excursions in post-dialysis serum calcium and iPTH levels.

SHORT SUMMARY

High calcium dialysate may increase serum calcium in hemodialysis patients, while low dialysate calcium may increase PTH. Individualization of dialysate calcium according to predialysis serum calcium levels may prevent or decrease unwanted excursions of both serum calcium and PTH.

Deferasirox nephrotoxicity-the knowns and unknowns

In 2005, the oral iron chelator deferasirox was approved by the FDA for clinical use as a first-line therapy for blood-transfusion-related iron overload. Nephrotoxicity is the most serious and frequent adverse effect of deferasirox treatment. This nephrotoxicity can present as an acute or chronic decrease in glomerular filtration rate (GFR). Features of proximal tubular dysfunction might also be present. In clinical trials and observational studies, GFR is decreased in 30-100% of patients treated with deferasirox, depending on dose, method of assessment and population studied. Nephrotoxicity is usually nonprogressive and/or reversible and rapid iron depletion is one of several risk factors. Scarce data are available on the molecular mechanisms of nephrotoxicity and the reasons for the specific proximal tubular sensitivity to the drug. Although deferasirox promotes apoptosis of cultured proximal tubular cells, the trigger has not been well characterized. Observational studies are required to track current trends in deferasirox prescription, assess the epidemiology of deferasirox nephrotoxicity in routine clinical practice, explore the effect on outcomes of various monitoring and dose-adjustment protocols and elucidate the long-term consequences of the different features of nephrotoxicity. Deferasirox nephrotoxicity can be more common in the elderly; thus, specific efforts should be dedicated to investigate the effect of deferasirox use in this group of patients.

Macrophages and recently identified forms of cell death

Recent advances in cell death biology have uncovered an ever increasing range of cell death forms. Macrophages have a bidirectional relationship with cell death that modulates the immune response. Thus, macrophages engulf apoptotic cells and secrete cytokines that may promote cell death in parenchymal cells. Furthermore, the presence of apoptotic or necrotic dead cells in the microenvironment elicits differential macrophage responses. Apoptotic cells elicit anti-inflammatory responses in macrophages. By contrast macrophages may undergo a proinflammatory form of cell death (pyroptosis) in response to damage-associated molecular patterns (DAMPs) released from necrotic cells and also in response to pathogen-associated molecular patterns (PAMPs). Pyroptosis is a recently identified form of cell death that occurs predominantly in subsets of inflammatory macrophages and is associated to the release of interleukin-1β (IL-1β) and IL-18. Deregulation of these processes may result in disease. Thus, failure of macrophages to engulf apoptotic cells may be a source of autoantigens in autoimmune diseases, excessive macrophage release of proapoptotic factors or sterile pyroptosis may contribute to tissue injury and failure of pathogen-induced pyroptosis may contribute to pathogen survival. Ongoing research is exploring the therapeutic opportunities resulting this new knowledge.

Bowel bacterial overgrowth as another cause of malnutrition, inflammation, and atherosclerosis syndrome in peritoneal dialysis patients

Bowel bacterial overgrowth syndrome (BBOS) is an important cause of gastrointestinal (GI) abnormalities. Proinflammatory cytokines (PICs) are excessively produced and accumulate because of kidney failure in dialysis patients who experience chronic infections such as BBOS. We explored the association between GL function, BBOS, and the malnutrition, inflammation, and atherosclerosis (MIA) syndrome. We studied GI malabsorption and maldigestion by analyzing fecal starch, sugar, fat, and nitrogen; intestinal protein permeability (alpha1-antitrypsin fecal clearance); and fecal chymotrypsin. We evaluated BBOS by breath hydrogen test (BHT) after a 3-day fat-and-carbohydrate-overload diet. Positive BHT was present in 10 patients, showing a high prevalence of GI macronutrient malabsorption and maldigestion, and compared with the other patients, the highest plasma levels of tumor necrosis factor alpha and interleukin 6 and lower levels of albumin and prealbumin. Those 10 patients were treated with a combination of several antibiotics, including neomycin, amoxicillin-clavulanate, and quinolones. Between 2 and 3 months later, the BHT, markers of nutrition, and PIC were re-tested. All treated patients showed an improvement in nutrition status and a lesser inflammatory pattern. The BBOS infectious process is found frequently in dialysis patients in association with GI malabsorption and maldigestion, malnutrition, and systemic inflammation. Hyperproduction of PIC because of BBOS induces MIA through a double pathway: GI disorders and deleterious systemic effects.