Urate-lowering agents for asymptomatic hyperuricemia in stage 3 - 4 chronic kidney disease: Controversial role of kidney function

Metabolic crosstalk and therapeutic interplay between diabetes and hyperuricemia

Hyperuricemia and diabetes mellitus (DM) are prevalent metabolic disorders with high comorbidity, imposing a substantial global public health burden. Their coexistence is not merely additive but synergistic, exacerbating metabolic dysregulation through mechanisms such as insulin resistance and β-cell apoptosis, ultimately establishing a vicious cycle. Both disorders induce acute and chronic damage to vital organs, particularly the cardiovascular, renal systems. Hyperuricemia aggravates diabetic complications, notably diabetic cardiomyopathy, nephropathy and retinopathy via oxidative stress, inflammation, and metabolic dysregulation.Current urate-lowering therapies (ULTs), such as xanthine oxidase inhibitors and urate transporter 1 (URAT1, also known as SLC22A12) antagonists, demonstrate potential benefits in ameliorating diabetic complications but face challenges including safety concerns and dose adjustments. Similarly, several glucose-lowering drugs also exhibit the benefits of improving hyperuricemia. This review summarizes the metabolic crosstalk and therapeutic interplay between hyperuricemia and DM, examines the pathogenic role of uric acid in diabetic complications, and discusses the benefits and challenges of existing ULTs and glucose-lowering drugs in disrupting this cycle of metabolic dysregulation and concurrent organ damage. We hope our findings deepen the comprehension of the intricate metabolic crosstalk between glucose and urate homeostasis, providing novel therapeutic insights for patients with comorbid DM and hyperuricemia.

Uric Acid Correlates with Serum Levels of Mineral Bone Metabolism and Inflammation Biomarkers in Patients with Stage 3a-5 Chronic Kidney Disease

Background and Objectives: Uric acid (UA) and the markers of mineral bone metabolism and inflammation are commonly altered in patients with chronic kidney disease (CKD) and are associated with the risk of cardiovascular complications and death. Studies point to a link between high serum UA and mineral bone homeostasis and inflammation, but controversy remains. The aim of this study was to evaluate the relationship between UA levels and mineral bone metabolism and inflammation biomarkers in a sample of Mexican patients with CKD 3a-5. Materials and Methods: This cross-sectional study included 146 Mexican patients with CKD 3a-5. In addition, 25 healthy subjects were included in the study with the aim of generating reference data for comparisons. Metabolic parameters including UA serum concentrations, mineral bone metabolism (parathormone (PTH), fibroblast growth factor 23 (FGF23), calcium, and phosphate), and inflammation (interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha (TNF-α)) biomarkers were measured in all of the samples and compared as a function of the estimated glomerular function rate (eGFR) or UA levels. Results: Intact PTH, FGF23, and cytokines were higher in advanced CKD stages. Patients with hyperuricemia had significantly higher values of FGF23 and TNF-α compared with those without hyperuricemia. The eGFR was found to be significantly and negatively correlated with all markers. Uric acid was significantly correlated with phosphate, iPTH, FGF23, and TNF-α, whereas iPTH was significantly correlated with FGF23, TNF-α, and FGF23. Finally, a multivariate analysis confirmed the relationship of eGFR with all the tested biomarkers, as well as other relationships of iPTH with UA and TNF-α and of FGF23 with UA and TNF-α. Conclusions: This study supports the relationship between uric acid and levels of mineral bone metabolism and inflammation biomarkers in patients with CKD at middle to advanced stages. In the follow-up of patients with CKD, monitoring and controlling UA levels through nutritional or pharmacological interventions could help in the prevention of alterations related to mineral bone metabolism.

Association between dietary patterns and chronic kidney disease combined with hyperuricemia

Background and aims: Chronic kidney disease (CKD) combined with hyperuricemia is a concerning health issue, but the association between this condition and dietary patterns remains poorly understood. The aim of this study was to assess the associations between dietary patterns and CKD combined with hyperuricemia. Methods: This cross-sectional study was conducted involving 12 318 participants aged 18-79 years during 2018-2020. Dietary intake information was collected using a validated 110-item food frequency questionnaire. Factor analysis was used to identify major dietary patterns. CKD was defined as the presence of albuminuria or an estimated glomerular filtration rate <60 mL min-1 1.73 m-2. Hyperuricemia was defined as serum uric acid levels >420 μmol L-1 both in men and women. Logistic regression models were applied to assess the association between dietary patterns and the risk of CKD combined with hyperuricemia. Results: Five major dietary patterns were identified: 'healthy pattern', 'traditional pattern', 'animal foods pattern', 'sweet foods pattern', and 'tea-alcohol pattern', which together explained 38.93% of the variance in the diet. After adjusting for potential confounders, participants in the highest quartile of the traditional pattern had a lower risk of CKD combined with hyperuricemia (OR = 0.49, 95% CI: 0.32-0.74, Pfor trend < 0.01). Conversely, participants in the highest quartile of the sweet foods pattern had a higher risk compared to those in the lowest quartile (OR = 1.69, 95% CI: 1.18-2.42, Pfor trend < 0.01). However, no significant association was observed between the healthy pattern, animal foods pattern and tea-alcohol pattern and the risk of CKD combined with hyperuricemia. Conclusions: Our results suggest that the traditional pattern is associated with a reduced risk of CKD combined with hyperuricemia, whereas the sweet foods pattern is associated with an increased risk.

Hyperuricemia, a Non-Independent Component of Metabolic Syndrome, Only Predicts Renal Outcome in Chronic Kidney Disease Patients without Metabolic Syndrome or Diabetes

Uric acid (UA) is elevated in metabolic syndrome (MS) and diabetes (DM). UA is associated with central obesity and blood glucose and is proposed as a criterion of MS. Previous reports showed that UA could predict renal outcome in CKD. However, recent clinical trials did not demonstrate the benefits of urate-lowering agents (ULA) for renal outcome. Whether the prognostic value of UA for renal outcome is independent of MS or secondary to MS in CKD patients is unknown. Our study included 2500 CKD stage 1−4 Asian patients divided by UA tertiles and MS/DM. In linear regression, UA was associated with obesity, C-reactive protein, and renal function. In Cox regression, high UA was associated with worse renal outcome in non-MS/DM, but not in MS/DM: hazard ratio (95% confidence interval) of UA tertile 3 was 3.86 (1.87−7.97) in non-MS/DM and 1.00 (0.77−1.30) in MS/DM (p for interaction < 0.05). MS was associated with worse renal outcome, but redefined MS (including hyperuricemia as the 6th criteria) was not. In conclusion, hyperuricemia is associated with worse renal outcome in non-MS/DM and is not an independent component of MS in CKD stage 1−4 patients. Hyperuricemia secondary to MS could not predict renal outcome.

Efficacy of Urate-Lowering Therapy in Patients With Chronic Kidney Disease: A Network Meta-Analysis of Randomized Controlled Trials

PURPOSE

The goal of this study was to systematically review the efficacy and safety of urate-lowering therapy in patients with chronic kidney disease (CKD).

METHODS

PubMed, the Cochrane Central Registration of Controlled Trials, and EMBASE databases and several websites were electronically searched to collect randomized clinical trials on the efficacy of urate-lowering therapy in CKD from inception to December 31, 2020. The key primary end points were uric acid or estimated glomerular filtration rate (eGFR) levels; the safety end points were death, renal event, cardiovascular event, and gastrointestinal event. A Bayesian network meta-analysis was conducted with the use of ADDIS and R software.

FINDINGS

A total of 17 randomized clinical trials involving 2059 patients were included. The results of network meta-analysis showed that urate-lowering therapy could reduce urate levels in patients with CKD. Febuxostat was the most effective treatment in lowering urate levels according to the rank probability. Urate-lowering therapy has the tendency to delay the decline of eGFR, but the difference was not statistically significant. Ranking probability showed that benzbromarone, febuxostat, and allopurinol ranked higher than placebo in reducing the decline of eGFR. There were no statistically significant differences between groups in the incidence of all adverse effects.

IMPLICATIONS

All urate-lowering therapies could reduce the urate level in patients with CKD, but the benefit of such therapy in renal disease is still unclear. PROSPERO identifier: CRD42020222601.

Hyperuricemia is associated with secondary hyperparathyroidism in patients with chronic kidney disease

PURPOSE

Hyperuricemia is common among patients with chronic kidney disease (CKD). In the general population, hyperuricemia is associated with secondary hyperparathyroidism (SHPT), in a mechanism that involves vitamin D metabolism. Data for patients with CKD, however, are scarce. We aimed to evaluate the relationship between hyperuricemia and mineral and bone metabolism, particularly hyperparathyroidism.

METHODS

This is a retrospective study that included 922 adult patients with stages 3, 4, or 5 CKD, not on dialysis. Clinical, demographic, and biochemical data were collected from charts and included uric acid, parathyroid hormone (PTH), 25(OH)-vitamin D, calcium, phosphate, renal function (estimated glomerular filtration rate-eGFR), and medications such as allopurinol, furosemide, and cholecalciferol. SHPT was defined as PTH > 65 pg/ml.

RESULTS

Our patients were mostly Caucasian women, with a mean age of 64 ± 16 years. SHPT and hyperuricemia were observed in 70% and 62.4% of patients, respectively. Patients with SHPT presented higher levels of uric acid (7.2 ± 1.8 vs. 6.6 ± 1.7 mg/dL, p = 0.0001) and a higher frequency of hyperuricemia (66% vs. 33%, p = 0.0001). Patients with hyperuricemia were mostly female, with lower eGFR, higher phosphate, and higher PTH. The risk of hypovitaminosis D was higher among patients with SHPT (69.7% vs. 53.1%, p = 0.0001). Hyperuricemia remained independently associated with hyperparathyroidism, (p = 0.033) even after adjustments for eGFR, calcium, phosphate, hypovitaminosis D, and use of allopurinol, calcitriol, furosemide, and cholecalciferol.

CONCLUSION

Hyperuricemia seems to be a contributing factor for SHPT in patients with CKD. The mechanisms behind this finding have yet to be elucidated.

Multiparametric MRI analysis for the evaluation of renal function in patients with hyperuricemia: a preliminary study

Background

To investigate the renal dysfunction in patients with hyperuricemia by employing a multiparametric MRI protocol, consisting of quantitative water molecule diffusion, microstructure, microscopic perfusion, and oxygenation measurements in kidneys.

Materials and methods

A total of 48 patients with hyperuricemia (HU) and 22 age-matched healthy control subjects (HC) were enrolled in the study. For each participant, three different functional magnetic resonance imaging (fMRI) sequences were acquired and analyzed, including intravoxel incoherent motion imaging (IVIM), diffusion tensor imaging (DTI), and blood-oxygen-level-dependent MRI (BOLD). Thereafter, an independent two-sample t-test was applied to discover the significant differences of MRI indices between the hyperuricemia (HU) and HC groups, and the specific potential biomarkers between two subgroups of HU group (asymptomatic hyperuricemia group (AH) and gouty arthritis group (GA)). Further, multivariate logistic regression analyses were performed to classify the AH from the GA group using the MRI indices with significant between-group differences. The receiver operating characteristic (ROC) curve was plotted, and the area under the ROC curve (AUC) was calculated to assess the performance of each MR index for differentiation between the AH and GA groups.

Results

Ten parametric values of the HU group were significantly lower than those of the HC group among the 14 fMRI parameters (P < 0.05). The cortical D, D^*, and f values and medullary D and R2^*values had significant differences between the AH and GA groups (P < 0.05). Combining the cortical D and f values and medullary R2* value gave the best diagnostic efficacy, yielding an AUC, sensitivity, and specificity of 0.967 ± 0.022, 91.67%, and 95.83%, respectively.

Conclusions

A multiparametric MR analysis plays an important role in the evaluation of renal dysfunction in hyperuricemia from multiple perspectives. It could be a promising method for noninvasive detection and identification of the early-stage renal damage induced by hyperuricemia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12880-021-00675-4.

The Association Between Uric Acid and Symmetric Dimethylarginine Levels in the Patients Undergoing Twice-weekly Hemodialysis

Background: Uric acid (UA) levels are associated with increased risk of cardiovascular events and mortality in hemodialysis patients. However, there are still conflicting data on the mechanism of increased risks related to uric acid levels. Objectives: This study assessed the association between uric acid levels and symmetric dimethylarginine (SDMA), as a marker of cardiovascular disease, in the subjects undergoing hemodialysis twice weekly. Methods: This was a cross-sectional study conducted in a tertiary hospital in Jakarta, Indonesia. We included all the adults who underwent hemodialysis twice weekly for at least three months in our hospital. Subjects already on uric acid lowering therapy, pregnant or lactating women and those with a history of malignancy were excluded. Uric acid and SDMA levels were measured at the same time in pre-dialysis venous blood samples. Bivariate analysis was performed using the Mann-Whitney U test or one-way ANOVA. Results: A total of 126 subjects were included. The median level of UA was 8.4 mg/dL (IQR: 2.6, min: 4.1, max: 13.6), and 72 subjects (57.14%) had UA levels of 8 mg/dL or higher. The median SDMA level was 535.5 (312.7) mmol/dL (min: 119.7, max: 1895.5). Subjects with UA levels > 8 mg/dL had significantly higher SDMA levels compared to subjects with UA levels < 8 mg/dL (550.1 (IQR: 357.25) vs 491.35 (IQR: 181.1), P: 0.0475). Conclusions: In twice-weekly hemodialysis patients, UA levels above 8 mg/dL were associated with increased SDMA levels.

Bioactive Compounds from Plant-Based Functional Foods: A Promising Choice for the Prevention and Management of Hyperuricemia

Hyperuricemia is a common metabolic disease that is caused by high serum uric acid levels. It is considered to be closely associated with the development of many chronic diseases, such as obesity, hypertension, hyperlipemia, diabetes, and cardiovascular disorders. While pharmaceutical drugs have been shown to exhibit serious side effects, and bioactive compounds from plant-based functional foods have been demonstrated to be active in the treatment of hyperuricemia with only minimal side effects. Indeed, previous reports have revealed the significant impact of bioactive compounds from plant-based functional foods on hyperuricemia. This review focuses on plant-based functional foods that exhibit a hypouricemic function and discusses the different bioactive compounds and their pharmacological effects. More specifically, the bioactive compounds of plant-based functional foods are divided into six categories, namely flavonoids, phenolic acids, alkaloids, saponins, polysaccharides, and others. In addition, the mechanism by which these bioactive compounds exhibit a hypouricemic effect is summarized into three classes, namely the inhibition of uric acid production, improved renal uric acid elimination, and improved intestinal uric acid secretion. Overall, this current and comprehensive review examines the use of bioactive compounds from plant-based functional foods as natural remedies for the management of hyperuricemia.

Constituents and Anti-Hyperuricemia Mechanism of Traditional Chinese Herbal Formulae Erding Granule

Erding granule (EDG) is a traditional Chinese medicine that has recently been identified as having anti-hypouricemic effects. However, the active components and underlying mechanism for this new indication have not been elucidated. Therefore, we compared the effects of different EDG extracts (water, 50% ethanol and 95% ethanol) on serum uric acid concentrations in the hyperuricemia model mouse. We also analyzed the constituents of different extracts by ultra-high performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS) to observe the variation between the active and inactive products. Extract activity and target site were evaluated by assessing uric acid- and inflammation-suppressing effects along with evaluating ability to regulate the uric acid transporter. The results showed that the 50% ethanol extract (EDG-50) had an obvious serum uric acid concentration lowering effect compared with water (EDG-S) and the 95% ethanol extract (EDG-95). UHPLC-Q-TOF-MS/MS analysis showed that EDG-50 was compositionally different to EDG-S and EDG-95. EDG-50 showed dose-dependent effects on reducing uric acid, suppressing inflammation and regulating uric acid transporters. Moreover, western blot analysis showed that EDG-50 down-regulated GLUT9 and URAT1 expression, and up-regulated OAT1 expression. Therefore, our findings enable the preliminarily conclusion that EDG-50 lowers serum uric acid concentrations, mainly by down-regulating the expression of GLUT9 and URAT1 proteins and up-regulating the expression of OAT1 proteins. This provides a research basis for clinical use of EDG as an anti-hyperuricemic agent.