The relationship between dialysis adequacy and serum uric acid in dialysis patients; a cross-sectional multi-center study in Iranian hemodialysis centers

Age-Related Effect of Uric Acid on Contrast-Induced Acute Kidney Injury of Patients Undergoing Coronary Angiography

Background

The association between uric acid (UA) and contrast-induced acute kidney injury (CI-AKI) following coronary angiography (CAG) has been established. However, whether the association would vary with age remained undetermined.

Methods

We performed the retrospective analysis based on the Cardio-renal Improvement II study, (ClinicalTrials.gov NCT05050877), which enrolled consecutive patients undergoing coronary angiography in 5 teaching hospitals in China from 2007 to 2020. The primary outcome was CI-AKI defined as the rise of serum creatinine (SCr) ≥ 0.5 mg/dL or 25% compared with the baseline value within 48 hours following CAG. The effect of age on the association between uric acid and CI-AKI was assessed by the logistic regression model.

Results

A total of 36,550 patients (mean age 63.08±5.6-year-old, 41.7% men) were included in the study. After adjusting for the confounders, the risk of CI-AKI between each quartile of uric acid was insignificant in the young group. In patients of the middle group, lower UA was associated with a lower risk of CI-AKI while higher UA was associated with a higher risk (Q1 OR: 0.853, 95% CI: 0.734-0.993; Q4 OR: 1.797, 95% CI: 1.547-2.09). In patients of the elder group, lower and higher UA were both associated with a higher risk of CI-AKI (Q1 OR: 1.247, 95% CI: 1.003-1.553; Q4 OR: 1.688, 95% CI: 1.344-2.124). The restricted cubic spline indicated a non-linear association between UA and CI-AKI in middle and elder age groups but a linear association in the young age group.

Conclusion

The association between uric acid and CI-AKI vary in patients of different age. Patients with elder age should maintain a middle level of uric acid while patients with middle age should consider a lower level of uric acid to reduce the risk of CI-AKI. The level of UA was an insignificant risk factor for CI-AKI in young patients.

Cytokines and chemokines systemic levels are related to dialysis adequacy and creatinine clearance in patients with end-stage renal disease undergoing hemodialysis

Although the clearance of low-molecular weight toxins is modulated by dialysis dose, the relationship between dialysis adequacy and middle systemic inflammatory mediators is often overlooked. Thus, the relationship between dialysis adequacy, pro- and anti-inflammatory cytokines and chemokines in hemodialysis (HD) patients was investigated. Forty-eight HD patients (19 women and 25 men) were investigated. Age, body mass index, time in HD, nutritional status, Kt/V and blood biochemical parameters was similar in patients of both sexes (P > 0.05). Thus, patients were stratified by dialysis adequacy measured by Kt/V method (adequate Kt/V ≥ 1.2). Post-HD urea, creatinine, cytokines (IFN-γ, IL-4 and IL-10) and chemokines (CCL-2, CCL-5, CXCL-8 and CXCL-10) were higher in patients with Kt/V < 1.2 (P < 0.05). Kt/V exhibited significant correlation with CXCL-10/IP-10 serum levels. Positive correlation between creatinine with IFN-γ, CCL-2/MCP-1, and CXCL-10/IP-10, and negative correlation with IL-10 was identified in patients with Kt/V < 1.2 (P < 0.05). In patients with Kt/V ≥ 1.2, only IL-10 was positively and CXCL-10/IP-10 negatively correlated with creatinine levels (P < 0.05). Kt/V and creatinine levels exhibited variable predictive value (Kt/V = 27% to 37%, creatinine = 29% to 47%) to explain cytokines and chemokines circulating levels in patients with adequate and inadequate dialysis dose. Taken together, our findings provide evidence that in addition to modulating uremic toxins levels, such as urea and creatinine, dialysis dose is associated with circulating levels of inflammatory mediators. Thus, low Kt/V results and creatinine accumulation are potential indicators of the systemic inflammatory stress determined by up-regulation of proinflammatory cytokines and chemokines, and downregulation of anti-inflammatory cytokines.

The Relationship Between Nutritional Status Based on Subjective Global Assessment and Dialysis Adequacy

Background: Malnutrition is common in patients undergoing hemodialysis and leads to a decrease in dialysis adequacy. The evaluation of dialysis adequacy is very important. Objectives: This study was done to investigate the relationship between patients’ nutrition status based on Subjective Global Assessment (SGA) and their dialysis adequacy. Methods: This cross-sectional descriptive study was conducted in Tehran, Iran, in 2019. Three hundred qualified patients were selected by cluster sampling. Before the dialysis session, measurement of height and weight and blood sampling for albumin, total iron-binding capacity (TIBC), blood urea nitrogen (BUN), and creatinine (Cr) assessment were performed. After the dialysis session, measurement of weight and second sampling for BUN were done. SGA forms were filled by patients. Patients’ dialysis adequacy was calculated based on the DaugirdasII formula, and data were analyzed using SPSS 21. Results: From 300 patients, 128 cases (42.7%) had normal nutrition status, while 148 cases (49.3%) had mild to moderate malnutrition and 24 cases (8%) had severe malnutrition with mean dialysis adequacy of 1.07. The present study showed a significant statistical relationship between malnutrition and education (P < 0.001), body mass index (BMI) (P = 0.03), albumin (P < 0.001), TIBC (P < 0.001), and dialysis adequacy (P < 0.001). Gender, age, and dialysis duration showed no significant relationship with nutrition status based on the SGA index. Conclusions: The findings showed a high relative frequency of malnutrition and a decrease in patients’ dialysis adequacy, which emphasize the patient’s educational level, proper management of nutrition along with regular consultations by nutritionists, better implementation of the dialysis procedure, and regular follow-up of dialysis adequacy.

Assessing the Adequacy of Hemodialysis Patients via the Graph-Based Takagi-Sugeno-Kang Fuzzy System

Maintenance hemodialysis is the main method for the treatment of end-stage renal disease in China. The Kt/V value is the gold standard of hemodialysis adequacy. However, Kt/V requires repeated blood drawing and evaluation; it is hard to monitor dialysis adequacy frequently. In order to meet the need for repeated clinical assessments of dialysis adequacy, we want to find a noninvasive way to assess dialysis adequacy. Therefore, we collect some clinically relevant data and develop a machine learning- (ML-) based model to predict dialysis adequacy for clinical hemodialysis patients. We collect 250 patients, including gender, age, ultrafiltration (UF), predialysis body weight (preBW), postdialysis body weights (postBW), blood pressure (BP), heart rate (HR), and blood flow (BF). An efficient graph-based Takagi-Sugeno-Kang Fuzzy System (G-TSK-FS) model is proposed to predict the dialysis adequacy of hemodialysis patients. The root mean square error (RMSE) of our model is 0.1578. The proposed model can be used as a feasible method to predict dialysis adequacy, providing a new way for clinical practice. Our G-TSK-FS model could be used as a feasible method to predict dialysis adequacy, providing a new way for clinical practice.

Assessment of the efficacy of hemodialysis on uric acid clearance in a sub-Saharan African population at the end stage kidney disease

Background

Uricemia dramatically rises with the stage of chronic kidney disease (CKD) and correlates with its mortality. Hemodialysis (HD) being the most used treatment at the end stage in sub-Saharan Africa, we sought to evaluate its efficacy on the clearance of uric acid (UAc) when used alone and twice per week.

Methods

A cross-sectional study of all consenting patients with CKD stage 5 recruited at random during HD sessions in a reference Centre in Cameroon from January to April 2017. We collected socio-demographic data, relevant clinical information, HD related variables, and measured serum uric acid (SUA) levels before and after the dialysis to assess the uric acid clearance. A clearance between 65 and 80% and above 80% was considered as low and good efficacy of HD respectively. Statistical analysis was performed using SPSS version 21.0. Factors associated with HD efficacy were assessed using Fisher’s exact test and are presented with their odds ratios (OR) and 95% confidence levels.

Results

One hundred four patients (53 females) were included. The mean age was 49.9 ± 13.3 years. Hypertension (25%) and chronic glomerulonephritis (16%) were the main suspected etiologies of CKD. The median time on renal replacement therapy by HD was 3 years [1; 6]. The prevalence of hyperuricemia was 81.9%. The means of SUA levels were 78.8 ± 13.8 mg/L and 26.4 ± 6.6 mg/L respectively before and after dialysis. Mean SUA clearance was 66% ± 10%. The efficacy of HD on UAc was moderate in 92 (63.9%) and good in 2 (1.4%) patients. Excess weight (OR 0.4 [0.2; 0.9]) and Kt/Vurea < 1.2 (OR 0.1 [0.04; 0.2]) significantly reduces the efficacy of HD.

Conclusion

HD used alone for 2 sessions per week has a moderate efficacy on uric acid clearance in CKD. Therefore, we should improve the Kt/V (> 1.2), and combine HD to uric acid lowering drugs and diet modifications to increase its efficacy.

Molecularly imprinted composite cryogel for extracorporeal removal of uric acid

In this study, uric acid (UA)-imprinted poly (hydroxyethyl methacrylate-N-methacryloyl-amido-L-cysteine methyl ester)-Fe³⁺ [poly(HEMA-MAC)-Fe³⁺] nanoparticle-embedded poly(acrylamide-methyl methacrylate) cryogel [p(AAm-MMA)-MIP] was synthesized for selective UA adsorption. The nanoparticles were prepared via molecular imprinting. The prepared p(AAm-MMA)-MIP cryogel was characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and swelling test. The swelling degree of the p(AAm-MMA)-MIP cryogel was determined as to 7.56 g H₂O/g cryogel. The prepared cryogel was used for UA adsorption from aqueous solution.The effects of pH (4.0-8.0), initial UA concentration (5-40 mg/L), temperature (4 °C, 25 °C and 35 °C) and contact time on the UA adsorption capacity were detailedly investigated. UA adsorption data were applied to Langmuir and Freundlich isotherm models. The adsorption data were well fitted with pseudo-second order kinetic model. The thermodynamic parameters (ΔG ͦ, ΔH ͦ, ΔS^o) demonstrated that the adsorption process was endothermic and spotaneous at 4 °C, 25 °C and 35 °C. The cryogel was also used for UA adsorption from human serum. The effects of the composite cryogel treatment on blood cells and hemostatic parameters were evaluated by using hemogram analyses, coagulation studies, thromboelastography and platelet aggregation studies. The results showed that the cryogel treatment has an allowable effect on blood cell counts and hemostatic parameters demonstrating the applicability of prepared composite cryogel for UA removal from human serum.