Effect of Urate-Lowering Therapy on the Progression of Kidney Function in Patients With Asymptomatic Hyperuricemia: A Systematic Review and Meta-Analysis

Hyperuricemia and its related diseases: mechanisms and advances in therapy

Hyperuricemia, characterized by elevated levels of serum uric acid (SUA), is linked to a spectrum of commodities such as gout, cardiovascular diseases, renal disorders, metabolic syndrome, and diabetes, etc. Significantly impairing the quality of life for those affected, the prevalence of hyperuricemia is an upward trend globally, especially in most developed countries. UA possesses a multifaceted role, such as antioxidant, pro-oxidative, pro-inflammatory, nitric oxide modulating, anti-aging, and immune effects, which are significant in both physiological and pathological contexts. The equilibrium of circulating urate levels hinges on the interplay between production and excretion, a delicate balance orchestrated by urate transporter functions across various epithelial tissues and cell types. While existing research has identified hyperuricemia involvement in numerous biological processes and signaling pathways, the precise mechanisms connecting elevated UA levels to disease etiology remain to be fully elucidated. In addition, the influence of genetic susceptibilities and environmental determinants on hyperuricemia calls for a detailed and nuanced examination. This review compiles data from global epidemiological studies and clinical practices, exploring the physiological processes and the genetic foundations of urate transporters in depth. Furthermore, we uncover the complex mechanisms by which the UA induced inflammation influences metabolic processes in individuals with hyperuricemia and the association with its relative disease, offering a foundation for innovative therapeutic approaches and advanced pharmacological strategies.

Research progress on bariatric surgery for hyperuricemia

Hyperuricemia is closely linked to obesity. As lifestyles and dietary patterns evolve, the prevalence of hyperuricemia has been on the rise. Bariatric surgery, an efficacious intervention for morbid obesity and its associated metabolic disorders, not only manages the weight of patients with severe obesity but also exerts beneficial therapeutic effects on hyperuricemia and gout. Moreover, it demonstrates substantial efficacy against other obesity-related metabolic conditions. However, the dramatic fluctuations in serum uric acid levels and acute gouty attacks in the immediate postoperative period are issues that should not be overlooked, and effective preventative strategies for some related adverse complications are still underexplored. This review discusses and reviews the advancements in the treatment of obese patients with hyperuricemia through bariatric surgery. By reviewing pertinent literature, it summarizes the short-term and long-term therapeutic outcomes of bariatric surgery for hyperuricemia, as well as common adverse reactions. Furthermore, by discussing preoperative and postoperative interventional measures and influential factors, this review aims to provide novel perspectives for the clinical management of hyperuricemia and offer insights for the prevention of related complications.

Preexisting Hyperuricemia Before High-Altitude Ascent is Associated with a Slower Recovery of Estimated Glomerular Filtration Rate Following Descent

Zhao, Linggong, Yujie Huang, and Xiaoling Tan. Preexisting hyperuricemia before high-altitude ascent is associated with a slower recovery of estimated glomerular filtration rate following descent. High Alt Med Biol. 00:00-00, 2024. Objectives: Hypoxia at high altitudes results in elevated uric acid (UA) and reduced estimated glomerular filtration rate (eGFR). However, the impact of a prolonged high-altitude sojourn on UA levels and renal function in patients with preexisting hyperuricemia warrants further exploration. The study was to investigate the eGFR and related factors in patients with preexisting hyperuricemia following exposure to high altitude. Methods: The study included 345 participants, who worked at a high altitude for 1 year. Anthropometric and laboratory indices were collected before ascent (i.e., baseline), as well as 20 and 80 days after descent. The participants were categorized into individuals with hyperuricemia (HUA) or normal uric acid (NUA) group based on the presence or absence of hyperuricemia at baseline. Results: No difference in baseline eGFR was observed between the two groups before ascend or on day 20 after descent (p > 0.05). However, on day 80, eGFR of the HUA group was lower compared with the NUA group (p < 0.05). Correlations existed between post-descent eGFR levels and variables, including sampling time, UA levels, total and direct bilirubin, and baseline grouping. Conclusions: After high-altitude exposure, the recovery of eGFR was delayed in participants with preexisting hyperuricemia. Preexisting hyperuricemia and high-altitude hypoxia jointly contribute to renal impairment.

Interaction between anemia and hyperuricemia in the risk of all-cause mortality in patients with chronic kidney disease

Aim

Both hyperuricemia and anemia are not only the manifestation of chronic kidney disease (CKD) but also related to its occurrence and development. A recent study has found that there was a synergetic effect between hyperuricemia and anemia on new-onset CKD. Herein we aimed to explore the roles of hyperuricemia and anemia in the all-cause mortality in patients with CKD.

Methods

Data of adult patients with CKD were extracted from the National Health and Nutrition Examination Surveys (NHANES) database in 2009-2018 in this retrospective cohort study. Weighted univariate and multivariate COX regression analyses were used to investigate the associations of hyperuricemia and anemia with all-cause mortality, and the evaluation indexes were hazard ratios (HRs) and 95% confidence intervals (CIs). The interaction effect between hyperuricemia and anemia on the risk of all-cause mortality was assessed via relative excess risk due to interaction (RERI) and attributable proportion of interaction (AP). Subgroup analyses of age, gender, CVD, hypertension, DM, and cancer were also performed to assess this interaction effect.

Results

Among 3,678 eligible patients, 819 died from all causes. After adjusting for covariables, we found that CKD patients with anemia (HR = 1.72, 95%CI: 1.42-2.09) or hyperuricemia (HR = 1.21, 95%CI: 1.01-11.45) had a higher risk of all-cause mortality. There was a potential synergetic effect between anemia and hyperuricemia on all-cause mortality, with RERI of 0.630 and AP of 0.291. Moreover, this synergetic effect was also observed in ≥65 years old (AP = 0.330), male (AP = 0.355), hypertension (AP = 0.736), non-hypertension (AP = 0.281), DM (AP = 0.371), and cancer (AP = 0.391) subgroups.

Conclusion

A potential synergetic effect between anemia and hyperuricemia on all-cause mortality was found in patients with CKD. However, further studies are needed to clarify the causal relationship between them.

Hyperuricaemia-associated all-cause mortality risk effect is increased by non-impaired kidney function - Is renal hyperuricaemia less dangerous?

BACKGROUND

Both hyperuricaemia and chronic kidney disease are known mortality risk factors. This study examined the modifying effect of renal function on hyperuricaemia-associated mortality risk, which is an issue that has not been studied before.

METHODS

Data on levels of serum uric acid (SUA), creatinine, cystatin C and other variables of persons aged 52-76 years were collected. Persons with SUA >410 μmol/L (75th percentile) were classified as clearly hyperuricaemic and persons with eGFR of ≤67 ml/min (25th percentile) as having reduced kidney function.

RESULTS

Reduced kidney function was associated with higher mortality in both SUA groups. When compared to individuals with SUA ≤410 μmol/L and eGFR >67 ml/min the hazard ratio (HR) for all-cause mortality was 1.53 (95 % CI: 1.26-1.84) in clearly hyperuricaemic persons with reduced kidney function, 1.26 (95 % CI: 1.02-1.55) in clearly hyperuricaemic persons with eGFR of >67 ml/min and 1.15 (95 % CI: 0.96-1.39) in persons with SUA ≤410 μmol/L and reduced kidney function. The HR for hyperuricaemia-related premature death was lowest in individuals with reduced eGFR, and it rose strikingly as the eGFR increased above 90 ml/min.

CONCLUSIONS

Reduced kidney function is a risk factor for mortality both in individuals with normal and elevated SUA. The hyperuricaemia-associated mortality risk is remarkably higher in individuals with normal kidney function than in individuals with reduced kidney function. Presumably overproduction of uric acid (metabolic hyperuricaemia) is a separate and more deleterious entity than hyperuricaemia resulting from reduced renal excretion of uric acid (renal hyperuricaemia).

Uric acid en route to gout

Gout and hyperuricemia (HU) have generated immense attention due to increased prevalence. Gout is a multifactorial metabolic and inflammatory disease that occurs when increased uric acid (UA) induce HU resulting in monosodium urate (MSU) crystal deposition in joints. However, gout pathogenesis does not always involve these events and HU does not always cause a gout flare. Treatment with UA-lowering therapeutics may not prevent or reduce the incidence of gout flare or gout-associated comorbidities. UA exhibits both pro- and anti-inflammation functions in gout pathogenesis. HU and gout share mechanistic and metabolic connections at a systematic level, as shown by studies on associated comorbidities. Recent studies on the interplay between UA, HU, MSU and gout as well as the development of HU and gout in association with metabolic syndromes, non-alcoholic fatty liver disease (NAFLD), and cardiovascular, renal and cerebrovascular diseases are discussed. This review examines current and potential therapeutic regimens and illuminates the journey from disrupted UA to gout.

Correlation between the increase in serum uric acid and the rapid decline in kidney function in adults with normal kidney function: a retrospective study in Urumqi, China

BACKGROUND

To examine the association between elevated serum uric acid (SUA) levels and the rapid decline in kidney function by conducting a retrospective cohort study on a physically healthy population in Urumqi, China.

METHODS

A cohort study of 2,802 physically healthy people with a normal estimated glomerular filtration rate (eGFR) was investigated from 2018 to 2021. The examination procedure included using questionnaires, taking physical measurements, and blood sampling. The rapid decline in kidney function was defined as eGFR > 5 mL·min^-1 ·(1.73 m² )^-1 year. The relationship between elevated SUA levels and the rapid decline in kidney function was assessed.

RESULTS

When performing the three-year retrospective analysis, 688 (28.55%) cases experienced a rapid decline in kidney function, and 52 (1.9%) cases developed chronic kidney disease (CKD). They were divided into the stable group and the rapidly declining kidney function group according to eGFR > 15 mL·min^-1·(1.73 m² )^-1. The comparison revealed a greater increase in uric acid in the rapidly declining kidney function group [0.30 (-0.29, 0.82) mg/dL vs. - 0.07(-0.54, 0.37) mg/dL, Z = - 8.822, P < 0.001]. The participants were further divided into four groups according to their uric acid levels in 2018 and 2021, which included the normal to normal (N-N) group, the normal to hyperuricemia (HUA) (N-H) group, the HUA to normal (H-N) group, and the persistently HUA (H-H) group. The decrease in eGFR was significantly higher in the N-H group than in the other three groups (χ² = 20.580, P < 0.001). The results of the multifactorial logistic regression analysis showed that elevated uric acid was a risk factor for the rapid decline in kidney function (OR = 1.640, P < 0.001).

CONCLUSION

Elevated SUA levels were a risk factor for the rapid decline in kidney function in the Chinese health examination population. Higher SUA levels might predict the occurrence of progressive kidney impairment.

Vegan Diet Is Associated with a Lower Risk of Chronic Kidney Disease in Patients with Hyperuricemia

Hyperuricemia is a well-known risk factor for chronic kidney disease (CKD). Little is known about whether a vegetarian diet is associated with a lower risk of CKD in patients with hyperuricemia. From 5 September 2005, to 31 December 2016, we retrospectively included clinically stable patients with hyperuricemia who received health check-ups at Taipei Tzu Chi Hospital. All participants completed a dietary habits questionnaire to determine whether they were omnivorous, lacto-ovo vegetarian, or vegan. CKD was defined as an estimated glomerular filtration rate <60 mL/min/1.73 m2 or the presence of proteinuria. A total of 3618 patients with hyperuricemia were recruited for this cross-sectional study, consisting of 225 vegans, 509 lacto-ovo vegetarians, and 2884 omnivores. After adjusting for age and sex, vegans had a significantly lower odds ratio (OR) of CKD than omnivores (OR, 0.62; p = 0.006). The OR of CKD remained significantly lower in vegans after adjusting for additional confounders (OR, 0.69; p = 0.04). Additionally, age (per year OR, 1.06; p < 0.001), diabetes mellitus (OR, 2.12; p < 0.001), hypertension (OR, 1.73; p < 0.001), obesity (OR, 1.24; p = 0.02), smoking (OR, 2.05; p < 0.001), and very high uric acid levels (OR, 2.08; p < 0.001) were independent risk factors for CKD in patients with hyperuricemia. Moreover, structural equation modeling revealed that a vegan diet was associated with a lower OR of CKD (OR, 0.69; p < 0.05). A vegan diet is associated with a 31% lower risk of CKD in patients with hyperuricemia. A vegan diet may be beneficial in reducing the occurrence of CKD in patients with hyperuricemia.

Whole transcriptome expression profiles in kidney samples from rats with hyperuricaemic nephropathy

Hyperuricaemic nephropathy (HN) is a common clinical complication of hyperuricaemia (HUA) and poses a huge threat to human health. Hence, we aimed to prospectively investigate the dysregulated genes, pathways and networks involved in HN by performing whole transcriptome sequencing using RNA sequencing. Six kidney samples from HN group (n = 3) and a control group (n = 3) were obtained to conduct RNA sequencing. To disclose the relevant signalling pathways, we conducted the analysis of differentially expressed genes (DEGs), Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. A competitive endogenous RNA (ceRNA) network was established to reveal the interactions between lncRNAs, circRNAs, mRNAs and miRNAs and investigate the potential mechanisms of HN. Ultimately, 2250 mRNAs, 306 lncRNAs, 5 circRNAs, and 70 miRNAs were determined to be significantly differentially expressed in the HN group relative to the control group. We further authenticated 8 differentially expressed (DE)-ncRNAs by quantitative real-time polymerase chain reaction, and these findings were in accordance with the sequencing results. The analysis results evidently showed that these DE-ncRNAs were significantly enriched in pathways related to inflammatory reaction. In conclusion, HUA may generate abnormal gene expression changes and regulate signalling pathways in kidney samples. Potentially related genes and pathways involved in HN were identified.

Higher dietary acid load is associated with hyperuricemia in Chinese adults: a case-control study

BACKGROUND

This study aims to explore the association between dietary acid load and hyperuricemia in Chinese adults.

METHODS

A case-control study was conducted. Adult participants with hyperuricemia were recruited as the cases and those without hyperuricemia were as the controls. Food consumption was evaluated by food frequency questionnaire (FFQ). Dietary acid load was assessed by potential renal acid load (PRAL) and net endogenous acid production (NEAP). Dietary acid load was divided into four levels: the first quartile (Q1), the second quartile (Q2), the third quartile (Q3) and the fourth quartile (Q4). Logistic regression model was applied for exploring the association between dietary acid load (PRAL and NEAP) and hyperuricemia. Odds ratio (OR) and its correspondence confidence interval (CI) were computed.

RESULTS

A total of 290 participants were eligible in this study, in which there were 143 individuals in case group and 147 in control group. A higher level of PRAL was found to be associated with odds of hyperuricemia. ORs of hyperuricemia for Q2, Q3 and Q4 of PRAL were 2.74 (95%CI: 1.94 ~ 3.88, p-value: 0.004), 2.90 (95%CI: 2.05 ~ 4.10, p-value: 0.002) and 3.14 (95%CI: 2.22 ~ 4.45, p-value: 0.001), respectively. There was a positive association between elevated NEAP and hyperuricemia. OR of hyperuricemia for Q2 was not material significance (OR:1.54, 95%CI: 0.93 ~ 2.53, p-value: 0.210), however, ORs of hyperuricemia for Q3 (OR: 2.40, 95%CI: 1.70 ~ 3.38, p-value: 0.011) and Q4 (OR: 3.27, 95%CI: 2.31 ~ 4.62, p-value: 0.001) were statistically significant.

CONCLUSION

Higher level of dietary acid load was found to be associated with hyperuricemia in Chinese adults, indicative of advocation of a well-balanced diet in this population.

The reality of treatment for hyperuricemia and gout in Japan: A historical cohort study using health insurance claims data

Hyperuricemia causes gout and has also been associated with metabolic syndrome and cardiovascular disease. Uric acid‐lowering drugs (ULDs) are used to reduce uric acid levels for the treatment of hyperuricemia and gout. However, there is a lack of robust and real‐world data on the history and treatment of patients with newly diagnosed hyperuricemia or gout in Japan. This retrospective, longitudinal, historical cohort study determined the characteristics of patients with hyperuricemia and/or gout, and prescription of, and adherence to, ULDs using data from the JMDC Claims Database. The primary evaluation population included 64 677 patients with newly diagnosed hyperuricemia and/or gout. Of these, only 26 501 (41.0%) had a prescription for ULDs at diagnosis. Even when ULDs were prescribed, the persistence rate of prescriptions declined over time, with a 54.4% persistence rate for ULDs at 12 months after the index diagnosis. In subgroups of patients with or without hypertension and diabetes, the rate of ULD prescription continuation was significantly higher in those with comorbidities than in those without (76.8% vs. 42.6% in those with vs. without hypertension, and 78.7% vs. 52.2% in those with vs. without diabetes). These finding suggest that therapeutic interventions to lower serum uric acid levels are under‐utilized for patients with newly diagnosed hyperuricemia and/or gout in Japan.