Improving Clearance for Renal Replacement Therapy

Displacing the Burden: A Review of Protein-Bound Uremic Toxin Clearance Strategies in Chronic Kidney Disease

Uremic toxins (UTs), particularly protein-bound uremic toxins (PBUTs), accumulate in chronic kidney disease (CKD) patients, causing significant health complications like uremic syndrome, cardiovascular disease, and immune dysfunction. The binding of PBUTs to plasma proteins such as albumin presents a formidable challenge for clearance, as conventional dialysis is often insufficient. With advancements in the classification and understanding of UTs, spearheaded by the European Uremic Toxins (EUTox) working group, over 120 molecules have been identified, prompting the development of alternative therapeutic strategies. Innovations such as online hemodiafiltration aim to enhance the removal process, while novel adsorptive therapies offer a means to address the high affinity of PBUTs to plasma proteins. Furthermore, the exploration of molecular displacers, designed to increase the free fraction of PBUTs, represents a cutting-edge approach to facilitate their dialytic clearance. Despite these advancements, the clinical application of displacers requires more research to confirm their efficacy and safety. The pursuit of such innovative treatments is crucial for improving the management of uremic toxicity and the overall prognosis of CKD patients, emphasizing the need for ongoing research and clinical trials.

Hemodiafiltration with endogenous reinfusion of the regenerated ultrafiltrate (HFR): towards a convective, diffusive, and adsorptive dialysis

Hemodiafiltration with endogenous reinfusion of the ultrafiltrate (HFR) is a dialysis technique characterized by a resin cartridge with adsorptive properties that combines the mechanisms of diffusion, convection, and adsorption in a single therapeutic regimen. After nearly 20 years of clinical experience with HFR, this article reviews the accumulated evidence with this technique, considering whether adsorption reduction, as a third purification mechanism, should be the next step in the treatment of hemodialysis patients. HFR, beyond producing an extensive removal of uremic toxins, has demonstrated to reduce the loss of nutrients and other physiological components during the dialysis session as compared to online hemodiafiltration, ameliorating the inflammatory state and oxidative stress in this population. In addition to its ease of use, the technique is also highly biocompatible and can be used in patients with a compromised vascular access. Based on these observations, HFR appears to be an especially useful therapy for high-comorbidity patients, including those with frailty, malnutrition, or cardiovascular disease. In this review, we, as a consensus panel of nephrologists experienced with HFR, survey existing literature and summarize our views on when to use this technique, which patients may be best suited for HFR, and how to effectively prescribe and monitor this modality of dialysis in daily clinical practice.

A nomogram to predict hyperkalemia in patients with hemodialysis: a retrospective cohort study

BACKGROUND

Hyperkalemia increases the risk of mortality and cardiovascular-related hospitalizations in patients with hemodialysis. Predictors of hyperkalemia are yet to be identified. We aimed at developing a nomogram able to predict hyperkalemia in patients with hemodialysis.

METHODS

We retrospectively screened patients with end-stage renal disease (ESRD) who had regularly received hemodialysis between Jan 1, 2017, and Aug 31, 2021, at Lishui municipal central hospital in China. The outcome for the nomogram was hyperkalemia, defined as serum potassium [K⁺] ≥ 5.5 mmol/L. Data were collected from hemodialysis management system. Least Absolute Shrinkage Selection Operator (LASSO) analysis selected predictors preliminarily. A prediction model was constructed by multivariate logistic regression and presented as a nomogram. The performance of nomogram was measured by the receiver operating characteristic (ROC) curve, calibration diagram, and decision curve analysis (DCA). This model was validated internally by calculating the performance on a validation cohort.

RESULTS

A total of 401 patients were enrolled in this study. 159 (39.65%) patients were hyperkalemia. All participants were divided into development (n = 256) and validation (n = 145) cohorts randomly. Predictors in this nomogram were the number of hemodialysis session, blood urea nitrogen (BUN), serum sodium, serum calcium, serum phosphorus, and diabetes. The ROC curve of the training set was 0.82 (95%CI 0.77, 0.88). Similar ROC curve was achieved at validation set 0.81 (0.74, 0.88). The calibration curve demonstrated that the prediction outcome was correlated with the observed outcome.

CONCLUSION

This nomogram helps clinicians in predicting the risk of PEW and managing serum potassium in the patients with hemodialysis.

Dysbiosis-Related Advanced Glycation Endproducts and Trimethylamine N-Oxide in Chronic Kidney Disease

Chronic kidney disease (CKD) is a public health concern that affects approximately 10% of the global population. CKD is associated with poor outcomes due to high frequencies of comorbidities such as heart failure and cardiovascular disease. Uremic toxins are compounds that are usually filtered and excreted by the kidneys. With the decline of renal function, uremic toxins are accumulated in the systemic circulation and tissues, which hastens the progression of CKD and concomitant comorbidities. Gut microbial dysbiosis, defined as an imbalance of the gut microbial community, is one of the comorbidities of CKD. Meanwhile, gut dysbiosis plays a pathological role in accelerating CKD progression through the production of further uremic toxins in the gastrointestinal tracts. Therefore, the gut-kidney axis has been attracting attention in recent years as a potential therapeutic target for stopping CKD. Trimethylamine N-oxide (TMAO) generated by gut microbiota is linked to the progression of cardiovascular disease and CKD. Also, advanced glycation endproducts (AGEs) not only promote CKD but also cause gut dysbiosis with disruption of the intestinal barrier. This review summarizes the underlying mechanism for how gut microbial dysbiosis promotes kidney injury and highlights the wide-ranging interventions to counter dysbiosis for CKD patients from the view of uremic toxins such as TMAO and AGEs.